From pv magazine Global

Researchers from India have proposed a novel bifacial electron transport layer (ETL)-free cell structure for flexible devices. They optimized this cell using SCAPS-1D simulation software, selecting the most effective combination of front transparent electrode (FTE), hole transport layer (HTL), and rear transparent electrode (RTE). The new structure has achieved a power conversion efficiency (PCE) surpassing 27%.

“ETL-free perovskite solar cells (PSCs) are the most promising and acceptable devices for developing flexible PSCs due to lower temperature processing, the simplest configuration, and the elimination of complex preparation routes, which reduces energy and time,” said the researchers. “They can be easily processed by roll-to-roll method, spray coating, inkjet printing, and can be encapsulated with low-cost flexible layers.”

The scientists began with a reference structure consisting of an FTE layer of PFTO; interfacial defect layer (IDL)1; a perovskite layer (FA0.75MA0.25PbI2.5Br0.5); IDL2; HTL layer of Spiro-OMeTAD; IDL3; and an RTE layer of Cu/Cu2O (PFTO/IDL1/FA0.75MA0.25PbI2.5Br0.5/IDL2/Spiro-OMeTAD/IDL3/Cu/Cu2O). They set the perovskite layer thickness to 600 nm.

“Upon selecting a suitable FTE, we observed that the lower value of conduction band offset (CBO) at the FTE/perovskite interface exhibits improved device performance due to the potential-well-like structure,” the group explained. “CuI and CuSCN show superior band alignment with the perovskite absorber layer compared to other HTLs, resulting in improved device performance. The electron affinity of RTE plays a crucial role in the band alignment at the RTE/HTL interface and, hence, the device performance.”

After finalizing the champion cell, the group investigated its bandgap and thickness.

“The device PCE increases up to an optimized bandgap of 1.4 eV, achieving a PCE of 24.65% (front illumination) and 25.48% (rear illumination). Beyond this bandgap, the PCE starts decreasing,” the results showed. “After optimizing the thickness of the absorber layer (800 nm) with a defect density of 1.0 × 10^14 cm−3, the PCE improves to 26.88% and 27.35%.”

They presented their results in “Performance optimization of ETL-free bifacial perovskite solar cells for flexible devices: A simulation study,” which was recently published in Next Energy. The team included researchers from India’s National Institute of Technology and the Indian Institute of Technology.

From pv magazine Global

Researchers from Mexico’s University of Sonora (UNISON) and the National Technological Institute of Mexico have conducted a numerical study of the thermal performance of a single-channel cooling system for photovoltaic modules.

In their simulation, they used different kinds of nanofluids, such as aluminum oxide (Al₂O₃), copper(II) oxide (CuO), and zinc oxide (ZnO). In addition, they have equipped the system with baffles, which are structures placed inside a cooling channel to improve heat removal.

“The system includes nine equally spaced baffles, which act as deflectors. The baffles are inclined to 45 degrees with a height of 1 cm. They favor the contact of the cooling fluids with the back of the panel, increasing the effective heat transfer coefficient,” explained the group.

The model included the five layers that make up a 13%-efficient photovoltaic panel – glass, ethylene vinyl acetate (EVA), solar cell, tedlar, and thermal paste, as well as the proposed aluminum channel with a height of 3 cm through which the cooling fluid circulates. “This cooling fluid can be either a nanofluid or pure water,” the scientists explained.

The numerical model was constructed using the software Ansys Fluent v20, based on the finite volume method. The PV system model and the flow of nanofluids under the laminar flow regime were validated against previous literature results, showing a “reliable basis for modeling PV systems and their interaction with nanofluids.”

In all cases, the metal oxides were suspended in water, with changing volumetric concentrations of 0, 0.01, 0.05, and 0.1, respectively. They used a range of reynolds numbers (Re), which are the measure used to determine whether fluid flow is smooth or chaotic, ranging from 18 to 42. A fluid inlet temperature of 34 C was assumed.

The scientists found that the nanofluid composed of CuO was the most effective, improving efficiency by 5.67% compared to pure water in the lowest Re range. “The concentration of 0.1 vol in the nanofluid produces a more effective reduction in the temperature of the photovoltaic cell, which reaches up to 15 % when the Reynolds number increases from 18 to 42. The increase in Re from 18 to 42 boosted electrical efficiency by 4%,” they further explained.

In addition, the group also found that electric efficiency improved by 1.40% by increasing the nanofluid concentration from 0 to 0.1 and that increasing the radiation from 200 W/m2 to 1,000 W/m2 decreased the efficiency by 6.5% for pure water and 5.5% for the nanofluid. “Baffles improve heat transfer in specific channel areas, resulting in a 2% increase in electrical efficiency due to fluid flow redirection and acceleration,” they concluded.

The cooling system was presented in “Numerical study of the thermal performance of a single-channel cooling PV system using baffles and different nanofluids,” published in Heliyon.

From pv magazine Global

An Indian-Chinese research team has developed a novel dual-axis solar tracking system based on sensors and a controller module.

“In this work, an attempt was made to design and implement a single tracking motor with dual axis for a simple yet effective control system,” the researchers said. “No programming or computer interface is required as standard electronic circuits are used. This system is independent and self-sufficient.”

The group explained that the novel system uses two different sensor types – an ultraviolet (UV) sensor and a micro-electromechanical solar (MEMS) sensor. “The UV sensor calculates the intensity of UV radiation received from the sun, and the MEMS sensor forecasts the sun’s path across the sky,” they added.

The data collected by those sensors are then fed into an arithmetic optimization-based PID (AOPID) controller, which uses arithmetic-based functions to attain a better response time, tracking accuracy, and disturbance rejection.

“The AOPID controller utilizes the inputs from the UV and MEMS sensors to modify the position of the solar panels and optimize energy capture,” the scientists further explained. “The controller achieves this by using a feedback loop that adjusts the controller’s proportional, integral and derivative gains to reduce the variation between the set-point and the real location of the solar panels through the use of arithmetic optimization algorithms.”

The academics tested the proposed system using MATLAB simulation software based on a 50 W simulated PV panel. They then compared its power production and consumption over a few hours to those of a simulated fixed-tilt PV system.

“The comparative energy analysis graph demonstrates that the dual-axis solar tracking system that was suggested was more productive than the fixed-tilt solar tracking system and matrix converter,” the researchers “Achieving a high net energy requires precisely adjusting the controller’s parameters and positioning the panels.”

The system was presented in the paper “Solar PV tracking system using arithmetic optimization with dual axis and sensor,” published in Measurement: Sensors. The research was conducted by scientists from China’s Xinxiang Vocational and Technical College and India’s Publon Research Centre.

From ESS news

ION Storage Systems has reached the 800-cycle mark with its solid-state battery, which it plans to bring into commercial production. The battery previously exceeded 125 cycles with less than five percent capacity loss in March, 2024.

The milestone of 800 cycles was achieved without encountering the common issues that can complicate the market readiness of solid-state batteries. The battery, which uses a ceramic electrolyte separator was tested without compression and showed no signs of swelling or volume change.

It means the battery will not require compression, swell budget, an extensive cooling system, or heavy fire barriers when rolled out, according to ION.

Neil Ovadia, VP of Supply Chain at ION, spoke with ESS News about the company’s progress following previous coverage in 2022.

“The last two years have been transformational. We’ve grown from about 20 employees to over 75, expanded into two larger buildings, and broken ground on our pilot manufacturing facility,” said Ovadia.

“We’re focused on the defense and consumer products markets initially, with plans to transition into electric vehicles and grid storage as we reduce costs and increase energy density,” he added.

Technical milestones

The technical achievement of the battery itself was the real highlight, according to Ovadia.

“We’ve made big strides in our product’s cycle life. We went from proving 125 cycles in March to achieving 800 cycles by July. Importantly, these cycles were achieved at room temperature with no compression or additional aids, demonstrating the true potential of our solid-state technology,” he said.

Robert Whittlesey, Principal Technical Program Manager at ION, told ESS News the technical process behind the testing, and highlighted the significance.

“800 cycles is significant because that’s beyond most consumer electronics. That starts to get into EV and grid storage applications, and even space-based applications that require a high cycle life. So this is something that could be used for all applications.”

Ovadia added, “It’s a confluence of all the characteristics of that battery that got to 800 cycles. One thing that you find in solid-state batteries is this requirement for compression, this requirement for heat, this coddling of the battery to achieve those cycles. It’s meaningful when you look at it as a final product, it makes it more expensive, heavier, and takes away from the potential and promise of a solid-sate battery.

A chart supplied by ION of the C/3 testing (a charge-discharge rate of charging every three hours, discharging every three hours) shows low capacity loss:

Grid storage possibilities

ION’s advancements with its solid-state batteries are highly relevant for grid-scale applications, with the company recently awarded $20 million from the US government’s ARPA-E Scale-Up program, which aims to accelerate the development of larger format cells for grid storage.

Ovadia said, “We are focused on scaling up our technology to produce larger, more cost-effective batteries. This involves collaborating with manufacturing partners and leveraging our university research partnerships to enhance both the mechanical and electrochemical aspects of our technology.”

He further emphasized the robustness and safety of their technology, stating, “Our batteries are inherently safer, eliminating the risk of fires associated with lithium-ion batteries. This makes them ideal for large-scale energy storage deployments where safety is paramount.”

Whittlesey added, “Our technology is not only safer but also more efficient in various temperature conditions. Traditional lithium-ion batteries require significant infrastructure to maintain optimal temperatures, which incurs additional costs. Our batteries can operate effectively across a broader temperature range, reducing the need for such infrastructure.”

Ovadia said that the current BESS grid infrastructure generally consumes energy as a parasitic draw for cooling, something that can be eliminated with the ability to operate at higher temperatures without the dangers of lithium-ion batteries.

Furthermore, Whittelsey pointed out the recyclability of the solution over traditional battery products with graphite anodes.

More to come

ION recently secured a supply agreement and investment from Saint-Gobain in late 2023, one of the world’s largest ceramics, glass and material suppliers to boost its manufacturing capabilities.

“We are working with several other large multinational partners to produce significant quantities at gigawatt-hour scales and achieve global reach in manufacturing,” Neil said, adding that further “significant announcements” from the company are due in the coming quarters.

The relatively early-stage company previously raised $8 million in 2019, and $31 million Series A funding in 2022.

Harris names clean energy advocate Governor Tim Walz as VP pick The Harris-Walz ticket wins on climate, according to clean energy supporters.

Quantum algorithm for photovoltaic maximum power point tracking Researchers have developed a quantum particle swarm optimization algorithm for maximum power point tracking that reportedly generates 3.33% more power in higher temperature tests and 0.89% more power in partial shading tests compared to conventional swarm optimization algorithms.

New discovery paves the way for more efficient perovskite solar cells Researchers from University of Texas have used computational methods to study the formation of polarons in halide perovskites. The findings revealed topological vortices in polaron quasiparticles.

SunPower goes bankrupt The residential solar installer has filed for bankruptcy, among the largest in a series of major bankruptcies in the industry.

Atlanta Motorsports Park goes solar The motorsports club with an F1-style track is installing a solar array that is expected to power about 60% of its operations.

A drone’s eye view helps find the perfect solar site Drone Drafting brings an array of aerial sensors to project planning and engineering.

From pv magazine Global

An international research team has developed a particle swarm optimization (PSO) algorithm based on quantum computing for real-time maximum power point tracking (MPPT) implementation in PV systems.

The scientists explained that the quantum version of the PSO algorithm capitalizes on the high speed of quantum computing and reduces the interval of random numbers in subsequent stages to avoid premature convergence. “A detailed implementation of the quantum aspect of the solution is provided using qubit states instead of classic particles and performing qubit spins using the y-axis rotation gates to perform the moves on the qubit states to search for the optimal solution,” they explained.

In quantum computing, a qubit or quantum bit is a basic unit of quantum information. It is the quantum mechanical analog of a bit in classical computing based on binary digits.

The proposed quantum particle swarm optimization (QPSO) algorithm is based on Schrödinger’s equation  – a differential equation that defines the behavior of wavefunctions in quantum mechanics.

“Simulating the behavior of human intelligence, rather than that of a flock of birds or a school of fish, necessitates capturing the thought processes of a complex social organism, which cannot be adequately described by a linear evolution equation,” the researchers said, seeking to describe the working principle of the algorithm. “It is believed that human thinking is as uncertain as a particle with quantum behaviors.”

The group tested the performance of the algorithm through Matlab Simulink software in a simulated PV array relying on four 213 W solar modules. It found the QPSO algorithm shows a strong ability to maintain performance close to that of conventional PSO across different environmental conditions. “It performs well in power optimization and maintaining system activity, as indicated by the power output and duty cycle values under both optimal and challenging conditions,” the academics added, noting that the proposed algorithm also requires “more prominent” computational demands.

They also found that, although the power achieved by the conventional PSO algorithm was approximately 0.15% higher than that attained by the QPSO algorithm under the same conditions, the QPSO was able to beat the conventional PSO in more challenging conditions.

“Specifically, the quantum algorithm generates 3.33% more power in higher temperature tests and 0.89% more power in partial shading tests,” they emphasized. “Additionally, the quantum algorithm displays lower duty cycles, with a reduction of 3.9% in normal operating conditions, 0.162% in high-temperature tests, and 0.54% in partial shading tests.”

The new algorithm was described in the study “Quantum maximum power point tracking (QMPPT) for optimal solar energy extraction,” published in Systems and Soft Computing. The research group included scientists from Algeria’s École Nationale Polytechnique and its École Nationale Supérieure de Technologies, Canada’s Université du Québec à Trois-Rivières, and the Norwegian Research Centre.

“Despite the classical algorithm’s marginal advantage in power output under normal conditions, the quantum algorithm illustrates superior performance across all other metrics, achieving higher power values and consistently lower duty cycle records, indicating more excellent general efficiency,” the scientists concluded. “Future work could explore adaptive algorithms that dynamically adjust to changing environmental conditions, enhancing efficiency and reliability.”

NASA installed the solar array for the Europa Clipper spacecraft, a robotic craft with a mission to reach Jupiter’s moon Europa by 2030. The large moon is one of 95 that orbit Jupiter, and it is studied closely due to its potential to host life in its global liquid ocean underneath its icy surface. 

Europa Clipper will be the largest spacecraft NASA has ever developed for a planetary mission. The craft is outfitted with large solar arrays that will serve as the primary power source for the mission. The arrays are large, as the Jupiter system is more than five times as far from the sun as Earth. 

The craft’s arrays are built as two five-panel wings. Each solar array measures 46.5 feet in length. To install the array, the team suspended the solar array on a gravity offload support system that helps support the weight of the solar array while it’s here on Earth. Next, NASA technicians will begin inspecting and cleaning as part of its assembly, test and launch operations. 

The array uses Azur Space 3G28 solar cells – with substrate panels from Airborne in the Netherlands, laid down by Leonardo in Italy and integrated into solar panels by Airbus Defence and Space in the Netherlands. The NASA Juice Mission also uses Azur Space 3G28 cells. 

The solar cells are designed for space travel, with self-annealing properties and the ability to operate under the intense radiation of space. More details can be found on an Airbus document.

The array is folded when launched and is designed for a passive deployment with spring-motorized hinges.

At launch, Europa Clipper will weigh approximately 13,000 lbs. Almost half of the weight will be fuel – nearly 6,000 lbs of propellant.

“Europa Clipper will launch in October 2024 on a SpaceX Falcon Heavy rocket from Kennedy Space Center in Florida. The spacecraft will fly by Mars, then back by Earth, using the gravity of each planet to increase its momentum. These so-called ‘gravity assists’ will provide Europa Clipper with the velocity needed to reach Jupiter in 2030,” said NASA.

From pv magazine Global

PeroNova, a U.S.-based startup specializing in solar perovskite technologies, has developed a solar perovskite module for building-integrated photovoltaics (BIPV) and space applications.

“Our novel interfacial treatment technology enhances the stability and reliability of perovskite films in tests, and in fabrication conditions. Thermal cycling resistivity tests demonstrated over 80% of initial power conversion efficiency after 2,500 cycles,” a PeroNova spokesperson told pv magazine.

The company currently develops lab-scale four-terminal (4T) perovskite-silicon tandem solar cells and 900 cm2 mini perovskite modules. The lab-scale cells have reportedly an efficiency of around 30%, while the modules achieve around 28% for the 4-T tandem configuration, 22% for outdoor applications, and 18% for space.

Founded in 2023,  PeroNova plans to address the demand for solar power in portable electronics, space and rooftop markets. “Our team has diligently worked to create a best-in-class American-made product that offers affordable and reliable renewable energy globally,” said co-founder and CEO, Min Chen, in a statement.

The company also recently announced it is collaborating with unspecified U.S. real estate developers intending to “bring large-scale implementation” of BIPV and agrivoltaics across the country. It will also be working with undisclosed space tech companies.

PeroNova has secured five patents from the U.S. Department of Energy. It also recently appointed Peter H. Diamandis, a U.S.-based entrepreneurial investor and founder of the XPRIZE Foundation, to its advisory board where he will “advise on product design, commercialization strategy and investor relations.”

Researchers at the Massachusetts Institute of Technology (MIT) have achieved a significant breakthrough in stabilizing a key component of perovskite solar cells. They have developed a method to synthesize Spiro-MeOTAD, a crucial material for charge transport, without using noble metals. This development led to the creation of a solar cell with an impressive 24.2% efficiency, although it experienced rapid degradation.

The research, led by Dr. Matthias J. Grotevent and Nobel Prize laureate Moungi G. Bawendi, demonstrated that their new method can produce a Spiro-MeOTAD material that remains stable even after 1,400 hours of testing at elevated temperatures (85°C) under continuous one-sun illumination. This durability is critical for materials exposed to the high temperatures and humidity typical of solar panel environments.

Their study, titled “Additive-free oxidized Spiro-MeOTAD hole transport layer significantly improves thermal solar cell stability,” underscores the potential of this new method. The researchers discovered that “even at low doping concentrations of 1%,” Spiro units could increase their electrical conductivity by orders of magnitude.

One of the key benefits of the material blend is its high glass transition temperature, which is above 115°C. This allows the solar cell to exhibit enhanced thermal properties, making it more suitable for use in high-temperature environments.

In all of this, the research team says that while the thermally stable Spiro unit is only in a solar cell that reaches 6% efficiency, they see a path via future research to stabilize the 24% efficiency solar cell.

According to the study, Spiro is currently an expensive material, priced online at $334 per gram. However, the researchers predict that the price could drop significantly with bulk orders reaching kilogram levels, potentially falling to $30 per gram or even $3/gram. When asked about the material’s cost by pv magazine USA, Dr. Grotevent estimated that a full-sized solar panel would require approximately 0.33 grams of Spiro, assuming a layer thickness of about 120 nanometers. This would result in a material cost of less than $0.003 per watt for a solar panel with an efficiency of over 20%, adding about $1.06 to the overall cost of the module.

Researchers are exploring three main approaches to deploying perovskites, which have so far seen limited use. The first method involves stacking perovskites atop silicon within the solar cell, a technique that has gained significant attention for its high efficiency, exemplified by Longi’s record-setting 34.6% perovskite-silicon tandem solar cell. The second approach, currently undergoing testing by GCL Perovskites, involves constructing nearly complete perovskite solar panels and layering them over similarly complete silicon solar panels to combine their outputs. The third approach features standalone perovskite panels without silicon, as demonstrated by the 1 MW China Three Gorges solar power facility.

Engineers from the University of Michigan have developed a new algorithm capable of designing optical multilayer film structures for applications, including solar cells.

OptoGPT (Opto Generative Pretrained Transformer) harnesses the computer architecture underpinning ChatGPT to work backward from desired optical properties to the material structure that can provide them.

The algorithm produces designs for multilayer film structures, consisting of stacked thin layers of different materials, reportedly within 0.1 seconds. Well-designed multilayer structures can maximize light absorption in a solar cell, and can also optimize design in other optical component manufacturers, such as telescopes. On average, OptoGPT designs contain six fewer layers than previous models, according to its creators. This means that its designs are easier to manufacture.

“Designing these structures usually requires extensive training and expertise as identifying the best combination of materials, and the thickness of each layer, is not an easy task,” said L. Jay Guo, professor of electrical and computer engineering at the University of Michigan. The model operates by treating materials at a certain thickness as words and encoding the associated optical properties as inputs. It seeks out correlations between these “words” and predicts the next word to create a “phrase” that achieves the desired property. “In a sense, we created artificial sentences to fit the existing model structure,” said Guo.

Guo is the corresponding author of “OptoGPT: A foundation model for inverse design in optical multilayer thin film structures,” a research paper that was recently published in Opto-Electronic Advances.

The paper says OptoGPT can “effectively deal with the non-trivial inverse design problem in multilayer structure … Combined with many proposed techniques, our model can unify the inverse design under different types of input targets under different incident angle/polarization, be versatile to different types of structures, as well as facilitate the fabrication process by providing diversity and flexibility.”

The researchers acknowledged that even though they used a large-scale dataset with 10 million samples for training, the dataset “only covers a small fraction of the expansive and complex design space associated with optical multilayer thin film structures.”

They said that because of the limitations in the training dataset, OptoGPT might not identify designs that fall outside the sampled design space.

“Close collaboration across multiple research groups is needed to obtain a better model for a more general and better photonic inverse design that expands to more complicated structures,” concluded the researchers.

A research team led by the Delft University of Technology in the Netherlands has outlined a roadmap for the optimization of monolithic perovskite/CIGS tandem solar cells and has found these PV devices may achieve a practical efficiency limit of 26.69%.

Using TCAD Sentaurus and GenPro4 modeling software, the scientists performed optical and electrical simulations of the materials and interfaces used in this type of tandem solar cell to better understand loss mechanisms and define a series of measures to improve efficiency.

The results were then calibrated by comparing simulated devices to three experimental devices: a tandem perovskite/CIGS solar cell; a single junction perovskite solar cell; and a single junction CIGS solar cell provided by Miasolé.

“The simulation platform is typically used in semiconductor research and development, as well as thin film and PV research. The CIGS sub-cell was based on on a state-of-the-art industrial device,” Delft University researcher, Paul Procel-Moya, told pv magazine.

The team noted that its work in this area differs from other numerical studies, as its focus is on the fundamental working mechanisms of the layers comprising the tunnel recombination junction (TRJ) and coupling-related loss calculations.

The study involved examining the energy alignment in TRJ layers to uncover the impact on external parameters of the baseline tandem solar cell, the exchange mechanisms between top and bottom cells, and the impact on the overall performance of the tandem system.

“Based on the main results, we propose a realistic roadmap for improvement of the tandem solar cell,” said Procel-Moya pointing to a four-pronged strategy towards improved performance. “We found in the simulation that the first stage should be fine-tuning the coupling tunneling junction between the two cells. It’s the first bottleneck.”

The first stage is to improve and optimize energy alignment at TRJ, while the second is to enhance the light management by minimizing the current mismatch between the sub-cells and reducing reflectance losses by adjusting perovskite and metallization thickness, for example. The third step is to improve the transport towards the tin oxide transport layer of the top cell. This step alone gave an estimated efficiency rise from 24.37 % to 25.13 %, according to the research. The fourth modification is to improve passivation in the top sub-cell.

Based on such modifications, the researchers calculated that the reference tandem cell could achieve an efficiency of 26.69 %. The team said that it expects that further “conversion efficiency gains are possible” by improving areas of the bottom cell, such as the absorber band gap energy and the passivation of the interface of CIGS and molybdenum layers.

Feedback received by Procel-Moya from other researchers currently experimenting at the lab scale confirmed that the TRJ focus was good advice. Looking ahead, the team will continue to do research on the physics of semiconductors PV and thin film with a focus on stability, studying reverse bias at the theoretical level, according to Procel-Moya.

The research appears in “Opto-electrical modelling and roadmap for 2T monolithic Perovskite/CIGS tandem solar cells,” published by Solar Energy Materials and Solar Cells. The team members were from the Netherlands institutions, Delft University of Technology, University of Twente, Eindhoven University of Technology, Netherlands Organisation for Applied Scientific Research (TNO), and U.S.-based MiaSole Hi-Tech Corp.

Solar corporate funding drops to $16.6 billion in H1 High interest rates, an uncertain rate trajectory and timeline, increasing trade barriers, supply chain challenges, concerns about the presidential election’s impact on the sector, and constantly evolving trade policies have created a climate of uncertainty.

First Solar commissions 1.3 million square-foot R&D facility The Jim Nolan Center for Solar Innovation in Lake Township, Ohio includes a high-tech pilot manufacturing line allowing for the production of full-sized prototypes of thin film and tandem PV modules.

Intersect Power closes $837 million in financing for three battery systems in Texas Each project comprises 86 Tesla Megapacks and will provide a capacity of 320 MWh of battery storage with a two-hour duration.

S&P Global launches daily spot market price assessment for solar panels The tool has been billed as the world’s first independent daily spot market price assessment for solar panels. S&P Global says it has been launched to aid transparency in technology pricing as solar modules become increasingly commoditized.

Generac awarded up to $200 million from DOE for solar and storage in Puerto Rico The funds seek to build energy resilience in Puerto Rico, where hurricanes and other extreme weather frequently leave residents without power.

North American solar power purchase agreements rise 3% in Q2 LevelTen Energy released its quarterly PPA Price Index Report, showing an increase in prices following a modest drop in Q1.

First Solar, Inc. commissioned its new research and development (R&D) innovation center in Lake Township, Ohio, which the company says is the largest facility of its kind in the Western Hemisphere.

The Jim Nolan Center for Solar Innovation is dedicated to the late James “Jim” F. Nolan, a former member of First Solar’s Board of Directors and the architect of the company’s cadmium telluride (CdTe) semiconductor platform.

According to a study by the National Renewable Energy Lab (NREL), in 2023 CdTe represented  about 16% of the U.S. solar market. First Solar is a leader in CdTe technology and differentiates itself not only by the use of the thin film technology, but also by its vertically integrated manufacturing process, domestic production and commitment to responsible solar. At the company’s California Technology Center (CTC) in Santa Clara, First Solar recently achieved a 23.1% efficient CdTe cell, a new world record certified by NREL.

“Thin films are the next technological battleground for the solar industry because they are key to commercializing tandem devices, which are anticipated to be the next disruption in photovoltaics,” said Mark Widmar, chief executive officer, First Solar. “While the United States leads the world in thin film PV, China is racing to close the innovation gap. We expect that this crucial investment in R&D infrastructure will help maintain our nation’s strategic advantage in thin film, accelerating the cycles of innovation needed to ensure that the next disruptive, transformative solar technology will be American-made.”

The new research facility covers 1.3 million square feet and includes a high-tech pilot manufacturing line allowing for the production of full-sized prototypes of thin film and tandem PV modules. Prior to the commissioning of the Jim Nolan Center, First Solar was using a manufacturing line at its Perrysburg, Ohio facility for product development efforts. With a dedicated R&D center, First Solar expect to “accelerate innovation cycles.”

The company reports that it will have approximately a half-billion dollars invested in R&D and that building out R&D infrastructure will create approximately 300 new jobs by 2025, the majority of which will be located at the Jim Nolan Center.

First Solar is also involved in perovskite solar development after announcing last year the acquisition of Evolar, the Swedish perovskite specialist. First Solar said in a statement that the acquisition will accelerate the development of next generation PV technology, including high efficiency tandem devices. It aims to integrate Evolar’s know-how with its existing research and development streams, intellectual property portfolio, and expertise in developing and commercially scaling thin-film PV.

In addition to R&D planned at the Jim Nolan Center, the company expects to also commission a perovskite development line at its Perrysburg, Ohio, campus in the second half of 2024.

First Solar reports it has invested almost $2 billion in R&D, operates laboratories in Santa Clara, California, and Perrysburg, Ohio, in the US, and Uppsala in Sweden.

At the end of 2023 First Solar had 16.6 GW of annual global nameplate manufacturing capacity and is expected to achieve over 25 GW of capacity by 2026. First Solar expects to commission new manufacturing facilities in Alabama in the second half of 2024 and Louisiana in the second half of 2025, bringing its total U.S. nameplate capacity to 14 GW by 2026.

U.S. manufacturer Peak Energy announced it has secured a $55 million Series A funding round to scale production of grid-scale sodium-ion batteries.

The funding round was led by Xora Innovation, a investing platform of Temasek. The Series A also included participation from Eclipse, strategic partner TDK Ventures, and new investors Lachy Groom, Tishman Speyer, TechEnergy Ventures, Doral Energy-Tech Ventures and DETV-Scania Invest.

Sodium-ion batteries are a proven battery chemistry that offers some advantages in cost, supply chain security, and safety when compared with conventional lithium-ion batteries.

(Read: “Sodium-ion batteries – a viable alternative to lithium?”)

Peak Energy said sodium-ion batteries will help support the transition to renewable energy by storing and dispatching electricity from intermittent sources like solar and wind. With Wells Fargo forecasting a 20% increase in U.S. electricity demand by 2030 after a decade of flat demand, more storage is needed to ensure renewable energy can deliver reliable power when it is needed most, rather than relying on new natural gas reserve power.

“As energy demand grows, we must capitalize on the potential of renewables to provide dependable, inexpensive energy to fuel a new era of technological advancement. Utility-scale storage powered by sodium-ion is the answer to securing this future on a resilient, decarbonized grid,” said Landon Mossburg, chief executive officer, Peak Energy.

Peak Energy said the new capital will help it enter the next phase of growth, launching the first full-scale production of sodium-ion storage in the U.S. The company’s battery technology is set to be deployed with “a select group of six premier customers” in its pilot program in 2025. The customer base includes three of the five largest Independent Power Producers and electric utility companies in the nation.

The company launched from stealth less than a year ago with a $10 million seed round and the addition of Apple and Tesla veteran Liam O’Connor as co-founder and chief operations officer.

Peak Energy said it is on track to break ground on its first domestic “giga-scale” sodium ion battery in 2027.

From pv magazine Germany

A team from Saarland University in Germany has secured funding from the European Innovation Council (EIC) Pathfinder program to develop elastocalorics heating and cooling technology as an alternative to heat pumps and air conditioning systems.

The €4 million ($4.36 million) EIC Pathfinder Challenge research project aims to develop a prototype for decentralized room air conditioning within three years. According to the research team, the technology is rated by the World Economic Forum (WEF) as one of the “TOP Ten Technologies 2024.” The US Department of Energy and the European Commission have also declared it to be the most promising alternative to conventional heating and cooling.

The solid-state heating and cooling process is based on transporting heat into or out of a room by loading and unloading a so-called shape memory material, for example in the form of wires. The material absorbs heat when it is loaded, for example when it is pulled, and releases it again when the load is removed.

The researchers, led by elastocalorics pioneer Paul Motzki, are using the superelastic nickel-titanium alloy for this purpose. Materials made from this alloy return to their original shape after deformation because they have two crystal lattices and thus two phases. While water, for example, assumes the solid, liquid and gaseous phases, in nickel-titanium both phases are solid but merge into one another.

Motzki, who holds a bridge professorship between Saarland University and the Center for Mechatronics and Automation Technology (ZeMA), is leading a consortium as part of the SMACool project, which is now funded by the EIC. The consortium also includes the universities in Ljubljana and Naples, as well as Irish company Exergyn.

The aim is to jointly develop a prototype of an air conditioning unit for residential buildings. Fresh air will flow in through narrow ventilation slots in the external walls and be heated or cooled as required until the desired temperature for the room behind is reached.

“With our technology, we don’t want to heat and cool houses with a central system, but rather each individual room in a decentralized and individual way,” said Motzki.

The compact unit to be developed could also be installed directly in new buildings with ventilation systems in the future.

With an electrocaloric system, temperature differences of around 20 C can be achieved when cooling and heating. The technology could become an alternative to conventional cooling and heating methods, as it does not require coolants and uses considerably less energy.

“The efficiency of elastocaloric materials is more than ten times higher than today’s air conditioning or heating systems – they will require significantly less electricity,” said Motzki.

Teams in Saarbrücken, Germany, have spent around 15 years researching and developing a technology using thin sheets of nickel-titanium to achieve optimal cooling or heating effects in circulatory systems. This includes creating a cooling and heating demonstrator and a continuously operating refrigerator.

From pv magazine Global

A group of researchers led by the University of Toledo in the United States have fabricated an all-perovskite tandem solar cell with a wide-band-gap top cell based on tin-lead (Pb-Sn) perovskite and a low-band-gap bottom cell relying on a conventional perovskite substrate.

“The technology readiness level (TRL) of the tandem device investigated in this study is still low at TRLs 2-3,” the research’s corresponding author, Zhaoning Song, told pv magazine. “Our work, however, proves the feasibility of enhancing the stability of all-perovskite tandem solar cells, but more work needs to be done to apply this technique to industrial production.”

The key feature of the tandem cell is the top device’s hole transport layer (HTL), which was fabricated with a Pb-doped compound known as poly[3-(4-carbox- ybutyl)thiophene-2,5-diyl] (P3CT), a material that reportedly offers excellent stability and relatively high hole mobility.

“We introduce Pb doping to increase its work function and minimize the energy level offset with the Sn-Pb perovskite,” the academics explained, noting that P3CT represents a valid alternative to commonly used PEDOT-PSS. “The Pb dopants also provide nucleation sites to enable high-quality Sn-Pb perovskite film growth.”

The group built the top cell with a substrate made of indium tin oxide (ITO), the novel HTL, the Sn-Pb perovskite absorber, an electron transport layer (ETL) based on buckminsterfullerene (C60), a bathocuproine (BCP) buffer layer, and a silver (Ag) metal contact.

The champion cell built with this architecture achieved a power conversion efficiency of 22.7%, an open-circuit voltage of 0.884 V, a short-circuit current density of 32.0 mA cm2, and a fill factor of 80.3%. It was then combined in a tandem device with an 18.7%-efficient bottom cell based on a perovskite absorber with a bandgap of 1.7 eV, an HTL made of a phosphonic acid called methyl-substituted carbazole (Me-4PACz) and an ETL relying on C60.

The champion P3CT-based tandem achieved an efficiency of 27.8, an open-circuit voltage of 2.147 (2.146) V, a short-circuit current density of 15.7 mA/cm2, and a fill factor of 82.6%.

“The P3CT-based tandems also show a higher average efficiency of 27.0% than PEDOT: PSS-based devices, proving excellent reproducibility of the high-efficiency tandems with the P3CT-Pb HTL,” the group emphasized. “Doping P3CT with Pb cations reduced the valence band offset with Sn-Pb perovskite and provided nucleation seeds for enhancing perovskite crystallization, resulting in improved film quality.”

The P3CT-based tandem was also found to retain around 97% of its initial efficiency after 1,000 h.

According to Song, the cost of the doping technique is almost negligible, as the lead iodide material used for doping is the same source material used for producing the perovskite absorber layer, and only a trivial amount is needed for doping. “Yet, it is worth noting that the polymer hole-transport material used in this study is still expensive due to its complexity of synthesis and limited production scale,” he further explained.

The new cell technology was introduced in the study “Suppressed deprotonation enables a durable buried interface in tin-lead perovskite for all-perovskite tandem solar cells,” published in Joule. “Our molecular design strategy for stabilizing the perovskite/HTL interface provides a direction for achieving efficient and stable all-perovskite tandem solar cells,” the team concluded.

From pv magazine Global

A research group led by Spain’s Valencia Polytechnic University has developed a novel single-parameter power forecasting method for residential PV installations.

The proposed approach defines interval prediction data rather than absolute figures, the scientists said, noting that it acknowledges and transparently communicates the natural variability in solar PV power generation.

“Opting for a single-parameter-focused model was a strategic decision aimed at simplifying the forecasting process,” highlighted the research group. “While multi-parameter models might offer more nuanced insights, they often entail increased computational complexity and resource demands. Our streamlined model promises ease of integration and user-friendliness, crucial for residential users and small-scale PV installations.”

The core aspect of the novel method is the selection of similar days in the past regarding direct radiation to forecast the power generation of a given day. A confidence level of 80% and a total of 10 similar days are selected for each prediction. After identifying similar days, the method uses a quantile-based approach to establish the prediction intervals, setting an upper and lower limit. In statistics, quantiles are used to divide the range of a probability distribution into continuous intervals with equal probabilities.

The system was trained and tested using a case study of a residential installation in Spain, which consists of 12,450 W panels and a 5 kW inverter for self-consumption, all of which installed in 2018. Hourly PV generation was recorded during the years 2019, 2020, 2021, and 2022. Hourly meteorological data for the area was obtained from the database Open Meteo.

The forecasting technique was used to predict PV power generation in 2020, based on the algorithm to search for similar days always within a range of two years before the target day. In the same period, it was compared to four classical forecasting methods: linear regression model (Alt1); gradient boosting regressor (Alt2); gradient boosting with lags (Alt3); and long short-term memory (LSTM) network (Alt4).

“The models’ performance was evaluated using Key Performance Indicators (KPIs) like prediction accuracy, prediction interval width, actual confidence level, and mean error. This thorough approach ensured a balanced assessment, emphasizing the strengths and limitations of each method,” said the researchers.

The proposed method achieved a mean absolute error (MAE) of 0.1490 kW, a mean squared error (MSE) of 0.0917 kW2, a root mean squared error (RMSE) of 0.3029 kW, an average width of intervals (AWI) of 0.3365 kW, a coverage probability (CP) of 91.55%, and an overall interval error (OIE) of 0.3789 kW. Alt1 showed an MAE of 0.3374 kW, an MSE of 0.2428 kW2, an RMSE of 0.4928 kW, an AWI of 0.9312 kW, a CP of 78.69%, and an OIE of 0.4117 kW.

Alt2 had an MAE of 0.2558 kW, an MSE of 0.2044 kW2, an RMSE of 0.4521 kW, an AWI of 0.7464 kW, a CP of 80.12%, and an OIE of 0.4031 kW. Alt3 recorded an MAE of 0.1379 kW, an MSE of 0.0768 kW2, an RMSE of 0.2771 kW, an AWI of 0.4890 kW, a CP of 91.72%, and an OIE of 0.2355 kW. Alt4 showed an MAE of 0.1282 kW, an MSE of 0.0684 kW2, an RMSE of 0.2616 kW, an AWI of 0.3522 kW, a CP of 80.72%, and an OIE of 0.2642 kW.

After analyzing the numerical results, the researchers verified how the proposed approach could help PV system owners achieve energy savings. According to their results, the average monthly energy bill decreased from $47.96 to $40,67, as energy imported from the grid decreased by 45.79 kWh, from 278 kWh to 232.21 kWh.

“By simply adjusting the operation schedules of the pool’s filtration system, the washing machine, and the dishwasher to align with peak solar production times, homeowners have been able to harness more solar energy, reducing reliance on the grid and decreasing the overall energy costs,” they concluded. “With advancements in home automation technology, even greater results can be achieved.”

Their findings were presented in “Interval-based solar photovoltaic energy predictions: A single-parameter approach with direct radiation focus,” published on Renewable Energy. The group comprised scientists from Spain’s Valencia Polytechnic University, the University of Valencia, and Ecuador’s Politecnica Salesiana University.

From pv magazine Global

A U.S. research team has fabricated a mini perovskite solar module based on a special polymer hole transport layer material that reportedly improves the panel stability and efficiency.

“The stability of perovskite modules has not been demonstrated to meet the required 25 years lifetime in many applications,” the research’s corresponding author, Jinsong Huang, told pv magazine, noting that the group was able to build the panel after identifying an ultraviolet (UV) light-induced perovskite degradation mechanism as one of the main causes affecting perovskite module stability.

“We report degradation mechanisms of p-i-n–structured perovskite solar cells under unfiltered sunlight and with LEDs,” the scientists explained, adding that they initially detected the cause of UV light-induced degradation in outdoor testing in the weak chemical bonding between the perovskite layer, the hole-transporting materials (HTM) and the transparent conducting oxide (TCO) layer at the cell level. “This causes perovskite solar cell degradation under sunlight with strong UV components.”

To mitigate the effects of this degradation, the scientists upgraded the perovskite solar cells used for the mini modules with a hybrid HTM based on a combination of EtCz3EPA, a new molecule, and poly[bis(4-phenyl)-(2,4,6-trimethylphenyl)-amine bathocuproine (PTAA:BCP).

This combination purportedly resulted in a stronger interconnection layer at the interface of the perovskite and the substrate in outdoor testing. “We enhanced the bonding at the perovskite/HTM/TCO region via a phosphonic acid group that bonded to the TCO and via a nitrogen group that interacted with lead in perovskites,” the academics explained.

The cells were based on a substrate made of indium tin oxide (ITO), the novel HTM, the perovskite absorber, a buckminsterfullerene (C60) electron transport layer, bathocuproine (BCP), and a copper (Cu) metal contact.

The 15 cm2 perovskite solar module fabricated with this cell configuration was able to achieve a power conversion efficiency of over 16% and retain these efficiency levels for around 29 weeks of outdoor testing. The results were confirmed independently at the U.S. Department of Energy’s Perovskite PV Accelerator for Commercializing Technologies (PACT) accelerator.

“Real-world demonstration is a critical step towards commercialization, and we hope by PACT offering these capabilities researchers and companies can leverage this data toward improved reliability,” the researchers said.

Their work is described in the paper “Strong-bonding hole-transport layers reduce ultraviolet degradation of perovskite solar cells,” published in Science. The research team had members from the University of North Carolina, the Colorado School of Mines, the National Renewable Energy Laboratory (NREL), the University of Toledo, and the University of California San Diego.

“This research is a true collaboration between organic synthetic chemists and solar cell device engineers working together to solve big problems. Furthermore, the chemistry to prepare the molecule of interest in this study is relatively simple and just the tip of the iceberg,” stated Alan Sellinger, a professor at Colorado School of Mines in a press release. Looking at upcoming research projects, Huang said that the group will continue to “understand the degradation mechanisms and find methods to overcome them.”

From pv magazine ESS News site

In what is described as the world’s first, researchers at the Laboratory for Energy Storage and Conversion (LESC) have managed to devise design principles for enabling an anode-free all-solid-state battery.

LESC is a collaboration between the University of Chicago Pritzker School of Molecular Engineering and the University of California San Diego’s Aiiso Yufeng Li Family Department of Chemical and Nano Engineering.

“Although there have been previous sodium, solid-state, and anode-free batteries, no one has been able to successfully combine these three ideas until now,” said UC San Diego PhD candidate Grayson Deysher, the first author of a new paper outlining the team’s work.

To create a sodium battery, which is said to boast an energy density on par with lithium-ion batteries, the research team needed to invent a new sodium battery architecture.

It opted for an anode-free battery design, which removes the anode and stores the ions on electrochemical deposition of alkali metal directly on the current collector. Eliminating the anode enables reduced weight and volume, higher cell voltage, lower cell cost, and increased energy density, but brings its own challenges.

“In any anode-free battery there needs to be good contact between the electrolyte and the current collector,” Deysher said. “This is typically very easy when using a liquid electrolyte, as the liquid can flow everywhere and wet every surface. A solid electrolyte cannot do this.”

However, the liquid electrolytes create a buildup called solid electrolyte interphase while steadily consuming the active materials, reducing the battery’s lifetime.

To continue reading, please visit our new ESS News website.

From pv magazine Global

The international research group led by Professor Martin Green from the University of New South Wales (UNSW) in Australia has published Version 64 of the “solar cell efficiency tables” in Progress in Photovoltaics.

The scientists said they have added 19 new results to the new tables since December.

Strong progress was reported across the whole range of solar cell technologies including silicon, chalcogenide, organic and perovskite.

A major new result is the 27.3%-efficient n-type silicon heterojunction interdigitated-back-contact (HBC) solar cell unveiled by Chinese manufacturer Longi in late May. “The cell, establishing a new outright record for silicon, has both polarity contacts on the rear surface restricting loss by the absence of contacts on the front illuminated surface,” the paper reads. “An all-laser patterning process was used for the more complex rear surface patterning required for such devices.”

Another result is the 34.2% power conversion efficiency that Longi achieved for a perovskite-silicon tandem solar cell in April with an updated value of 34.6% obtained in May held in reserve and reported at June’s Shanghai New Energy Conference (SNEC).

The list also includes a 25.6%-efficient large-area n-type TOPCon cell fabricated by JA Solar, a 26.8%-efficient large-area n-type silicon cell fabricated by Longi, and the 24.9% efficiency that Singapore-based Maxeon reached for its IBC solar module.

Furthermore, the tables now include the 22.6% efficiency that US-based First Solar achieved for a 0.45 cm2 cadmium-telluride (CdTe) cell, as well as several other thin-film solar cells based on kesterite (CZTSSe) or copper, gallium, indium, and diselenide (CIGS). These include reaching the 15% efficiency milestone both for small-area CZTSSe cells made by the Chinese Academy of Science and a full-sized 0.8 m2 perovskite module made by Microquanta founded by former UNSW students.

In Version 63 of the tables, released in December, the researchers added 6 new results. The group has seen major improvements in all cell categories since 1993, when the tables were first published.

The research group includes scientists from the European Commission Joint Research Centre, Germany’s Fraunhofer Institute for Solar Energy Systems and the Institute for Solar Energy Research (ISFH), Japan’s National Institute of Advanced Industrial Science and Technology, and the US National Renewable Energy Laboratory.

SolarEdge Technologies, a provider of inverters, module level power electronics, battery energy storage, and other related technologies, announced it has been selected by Rutgers University to support research of dual-use agrivoltaics.

Agrivoltaics is the practice of installing solar arrays on function farmland. The arrays are typically raised higher than a traditional array, leaving space for crops to grow below.

Administered by the New Jersey Board of Public Utilities, Rutgers will assist the Dual-Use Solar Energy Pilot Program. The program is a three-year study of 200 MW of agrivoltaic installations.

“The aim of our research is to develop knowledge that will help to establish practices that can help improve both the sustainability and viability of farms through safe and regulated adoption of solar energy,” said Margaret Brennan-Tonetta, director of resource and economic development, New Jersey Agricultural Experiment Station.

(Read “Has the US caught up with European agrivoltaic deployment?”)

The program includes three project sites, including a different panel mounting method to understand effects on cost, agricultural production, and electricity generation.

• Rutgers Animal Farm in New Brunswick has vertically mounted bifacial panels and will be used for the production of forage crops and beef cattle grazing (170 kWDC installed and grid-connected)

• Snyder Research and Extension Farm in Pittstown has single-axis trackers and will be used for hay production (94.5 kWDC installed and 82.4 kWDC grid-connected)

• Rutgers Agricultural Research and Extension Center in Bridgeton has single axis trackers with both single-wide and double-wide rows of panels and will be used for the production of vegetable and staple crops (255 kWDC installed and 48.6 kWDC grid-connected)

Each site will use SolarEdge’s module level power electronics (MLPE) to collect and analyze production data.

“Agrivoltaics is a perfect example of a real ‘win-win’,” said Bertrand Vandewiele, general manager, SolarEdge North America. “This practice allows for expanded solar development to address climate change, without the land-use challenges often associated with ground mounted solar developments. It can also provide benefits for farmers, allowing a stable revenue stream and protection against climate hazards.”

Vandewiele shared that in the U.S., there are already more than 500 active agrivoltaics sites, adding a total of 9 GW of solar capacity to the grid. He said these numbers are likely to grow as interest in agrivoltaics has been greatly expanding, as indicated by the increase in support and funding for the sector. For example, the U.S. Department of Agriculture’s funding for agrivoltaics more than tripled from 2021 to 2022.

NJBPU, the New Jersey Department of Agriculture, the State Agricultural Development Committee, the New Jersey Department of Environmental Protection, and the Rutgers Agrivoltaics Program are participating in the pilot. 

(Read about a vertical solar study at Rutgers in “New Jersey farm studies agrivoltaics with vertically mounted solar“)

Research areas for the pilot program will include:

• Impact on yield and quality of vegetables, nursery crops, sod, cranberries, blueberries and grapes

• Impact on pastures and animals (sheep, cows, horses) grazing underneath solar panels

• Opportunities for Controlled Environment Agriculture (greenhouses and high tunnels), including the use of supplemental lighting powered by photovoltaics

• Greenhouse Gas (GHG) based-Life cycle assessment for conventional field production versus crops grown under agrivoltaic systems, including the impact on water consumption and renewable energy generation

• Optimal design of agrivoltaic systems for NJ farms (pole placement and height, panel type and efficiency, panel tilt angle, tracking systems, etc.)

• Economic opportunities and challenges for agrivoltaics in NJ

Read more global pv magazine coverage of agrivoltaics.

Planted Solar, a solar startup out of Oakland, California, received $20 million in Series A funding from the Bill Gates Breakthrough Energy Ventures and Khosla Ventures, as well as Department of Energy Funds to scale its terrain-following solar installation design.

The company installs its arrays like a sheet, densely packed together, rather than using typical row spacing. Instead of developing the land to be flat and uniform, the company’s solar mounts follow the terrain, tolerating up to a 27% slope. This helps reduce land development costs and allows for more energy-per-acre.

This may prove important, as the U.S. Bureau of Land Management forecasts the country will need 22 million acres for solar project deployment.

“In comparison to south-facing fixed tilt and tracker designs, a Planted array provides a comparable kWh/kWp yield when using a higher inverter loading ratio (ILR) and is substantially lower in cost of structural balance of system and installation, reduces the amount of civil work and civil risk, and requires a lot less land,” said Planted Solar.

The company said its design allows for a megawatt of solar to be installed on only two acres, less than the five acres typically required for a megawatt of solar capacity. Its simple terrain-following mount leads to a 50% reduction in balance of system costs and fewer installation hours.

“This adds up to a system with a lower build cost, higher DC system size, and similar annual kWh production,” said the company.

The terrain-following mounts are compatible with all conventional module formats and sizes, said the company.

After completing the design phase, the company uses installation robots to deploy the solar panels, which it said reduces installation time and costs. Planted Solar said its design mitigates impacts like erosion on the developed land, which is explained in a whitepaper.

“Planted’s low-impact approach to fixed-tilt solar PV foundation and table installation is novel in its automation, low impact/low disturbance, and tolerance to using existing ground conditions without grading. Furthermore, the low-area cross section of the Planted foundation legs should reduce local scour when compared to traditional pile. Installing using Planted’s methodologies will reduce disturbance and resultant hydrological and hydraulic impact to a site versus traditional installations of solar arrays,” said Planted Solar.

Planted Solar chief executive officer Eric Brown said it is rapidly “moving from pilots to portfolios.” The company announced it was selected for an 11 MW portfolio of projects in the Chicago area with Cultivate Power.

“Planted Solar gives our team a strategic tool to be stewards of the land and develop better projects with our community partners,” said Brian Matthay, co-founder and managing director of Cultivate Power. “Cultivate is focused on collaborating with landowners and communities so we can integrate solar seamlessly with the local environment and agricultural operations.”

Princeton NuEnergy (PNE), a New Jersey-based specialist in lithium-ion battery direct recycling, announced the close a Series A funding round with a strategic investment from Samsung Venture Investment Corporation.

Founded out of Princeton University in 2019, PNE developed a patented direct recycling technology for lithium-ion batteries. The low-temperature plasma-assisted separation process, trademarked as LPAS, produces battery-grade cathode and anode materials suitable for direct reintroduction into cell manufacturing. The company reports that this recycling is done at half the cost and is 70% less energy intensive.

PNE is now commercializing its lithium-ion battery recycling process that the company reports recovers up to 95% of materials found in all lithium-ion battery chemistries.

Recovering lithium and other critical battery materials is important as the U.S. ramps up electric vehicle produciton. While the U.S. is making strides toward manufacturing batteries, it is behind in the race for raw materials as China reportedly holds the majority of the world’s lithium refining capacity.

To advance lithium battery recycling, PNE has received over $55 million in grants, strategic and venture funding including investments from Honda Motor Co. Ltd., LKQ Corporation, Samsung Venture, Shell Venture, Traxys Group, Wistron Corporation, and the U.S. Department of Energy.

Investor demand for this 50% oversubscribed round brought PNE’s Series A total to $30 million. Samsung Venture and Helium-3 join the round’s previous investors. The funds will support construction of PNE’s first standalone, full-scale direct battery recycling advanced manufacturing facility.

“The incredible interest in our Series A round, capped off by a strategic investment from Samsung Venture Investment Corporation and Helium-3 Ventures, speaks to the importance of supporting a circular economy for lithium battery manufacturing here in the U.S.,” said Dr. Chao Yan, PNE’s co-founder and CEO. “This funding enables us to implement and demonstrate our capabilities at commercial scale, helping America meet the growing demand for high-performance batteries while also creating high-quality clean energy jobs.”

PNE was named to Time Magazine’s “America’s Top Greentech Companies 2024”

From pv magazine Global

Scientists from Rice University in Houston, Texas, have improved the stability of pervoskite solar cells by distributing 2D perovskites.

The scientists synthesized formamidinium lead iodide (FAPbI3) into ultrastable, high-quality photovoltaic films for high-efficiency perovskite solar cells. They hypothesized that using more stable 2D perovskites as a template could impart their stability to FAPbI3 during growth.

They fabricated four types of 2D perovskites to test the idea, two closely matching FAPbI3’s surface structure and two less well-matched, and used them to make different FAPbI3 film formulations. They found that the 2D crystal template improved both the efficiency and durability of FAPbI3 solar cells. Solar cells with 2D templates didn’t degrade after 20 days of generating electricity in air, while those without 2D crystals degraded significantly after two days.

“The addition of well-matched 2D crystals made it easier for FAPbI3 crystals to form, while poorly matched 2D crystals actually made it harder to form, validating our hypothesis,” said Isaac Metcalf, the lead author of the study. “FAPbI3 films templated with 2D crystals were higher quality, showing less internal disorder and exhibiting a stronger response to illumination, which translated as higher efficiency.”

The research team then found that by adding an encapsulation layer to the 2D-templated solar cells, stability was further improved to timescales approaching commercial relevance. According to their research paper – “Two-dimensional perovskite templates for durable, efficient formamidinium perovskite solar cells,” recently published in Science – the fabricated cell had a power conversion efficiency of 24.1% for a 0.5-square-centimeter active area and maintained 97% of their efficiency for 1,000 hours at 85 C under maximum power point tracking.

“Right now, we think that this is state of the art in terms of stability,” said Rice University engineer Aditya Mohite, “Perovskite solar cells have the potential to revolutionize energy production, but achieving long-duration stability has been a significant challenge.”

The team said that the findings could have an impact on light-harvesting, reduce manufacturing costs, and enable development of solar panels with that are lighter and more flexible than silicon solar panels.

“Perovskites are soluble in solution, so you can take an ink of a perovskite precursor and spread it across a piece of glass, then heat it up and you have the absorber layer for a solar cell,” Metcalf said. “Since you don’t need very high temperatures – perovskite films can be processed at temperatures below 150 C – in theory, that also means perovskite solar panels can be made on plastic or even flexible substrates, which could further reduce costs.”

Swift Solar announced the close of its $27 million Series A financing round, which follows on the heels of a $7 million award from the Department of Energy under the Advancing U.S. Thin-Film Solar Photovoltaics funding program.

The company, founded in 2017 is a spinout of MIT, Stanford University and the National Renewable Energy Laboratory (NREL), and specializes in perovskite tandem photovoltaics. The new technology combines metal halide perovskites with silicon or other perovskites to make tandem cells that have higher efficiency than traditional solar cells.

The $27 million funding round was co-led by Eni Next and Fontinalis Partners. Also joining the round are new and existing investors including Stanford University, Good Growth Capital, BlueScopeX, HL Ventures, Toba Capital, Sid Sijbrandij, James Fickel, Adam Winkel, Fred Ehrsam, Jonathan Lin, and Climate Capital.

The $7 million DOE funding is part of a $71 million investment, including $16 million from the Bipartisan Infrastructure Law, which supports research, development and demonstration projects in order to help grow the domestic solar supply chain. Swift Solar was one of four awardees that are working on tandem PV devices that pair established PV technologies like silicon and copper indium gallium diselenide (CIGS) with perovskites.

In total, Swift Solar has raised $44 million to scale its technology as it prepares to break ground on its first manufacturing facility.

“Solar is the future of energy—not just clean energy,” said Joel Jean, co-founder and CEO of Swift Solar. “Our advanced perovskite solar cells can outperform anything currently available on the market.”

A novel vapor deposition technology may help it to accelerate the manufacture of its tandem solution. The new method is a non-batch process that solves two problems associated with the use of established vapor processing in perovskite material manufacturing – the slow speed of deposition and the non-continuous nature of batch processing.

“Our deposition approach allows for the continuous deposition of a fully absorbing perovskite material within less than five minutes,” corresponding author Tobias Abzieher from Swift Solar, a U.S.-based perovskite PV startup, told pv magazine. “Solar cells prepared with these materials also outperform previously realized efficiencies of vapor processed inorganic perovskite solar cells significantly.”

In its announcement, Swift Solar noted that perovskite solar cell production uses less material and less energy, which should drive down manufacturing costs and carbon pollution, potentially decreasing the cost of solar by up to 30%. “The perovskite supply chain could be based entirely in the United States and aligned countries, creating a major opportunity to expand domestic manufacturing,” according to Swift.

Swift Solar’s initial products will be designed for integration in high-performance solar-powered products such as on car rooftops or space-based satellites, and the company says it will also serve traditional solar customers.

Swift Solar was recently named one of TIME’s Top GreenTech Companies in America. In April, The Solar Energy Manufacturers for America (SEMA) Coalition announced the Swift Solar was a new member.

This article was amended to remove mention of company developing rooftop product.

From pv magazine Global

Scientists from the Université de Sherbrooke in Canada have fabricated a prototype of a concentrator photovoltaic (CPV) module based on the so-called surface-mount technology (SMT) – a technique that is commonly used to mount electronic components to the surface of a printed circuit board (PCB).

The proposed SMT design used no wire bonding for cell emitter connection and is intended to increase heat dissipation in the CPV panel, which in turn reduces its operating temperature and increases its performance.

“The SMT, which uses a conductive solder paste for interconnection, has the advantage of being less expensive and faster for large-scale production, and SMT equipment takes up less space than wire-based wiring equipment,” they explained. “We have developed and employed the SMT process, which integrates assembly flexibility and enhanced alignment of solar cells, to assemble the solar cells larger than a millimeter in size.”

The 4-solar cell CPV module prototype uses a Fresnel lens to concentrate light onto cells soldered on a transparent glass PCB and protected by lamination layers. The emitter contacts are soldered through conductive solder joints to a glass PCB, which embeds metal tracks for the non-soldered areas. Transparent underfill fills the gap between the solar cell and the PCB to prevent reflections at the interfaces of the module’s bottom plate.

“Underfill fillets protect the sides of the solar cell to prevent short circuits and contribute to the thermomechanical stability of the assembly,” the research team stated. “The back face of the assembly is laminated with an EVA encapsulant and a Tedlar protective sheet to preserve the solar cells from the environment.”

The four cells used in the device are non-interconnected with each other, and are triple-junction III-V germanium solar cells, each with an active surface area of 8.751 mm². The cost of solar cells based on compounds of III-V element materials, named according to the groups of the periodic table that they belong to, has confined the devices to niche applications, such as drones and satellites. These are applications where low weight and high efficiency are more pressing concerns than costs.

The scientists mounted the 4-cell CPV SMT module on a 2-axis solar tracker from the Helios platform at the University of Sherbrooke.

The group took a series of electrical and temperature measurements on the system under real operating conditions and also conducted a series of simulations based on the finite element model (FEM), which is a numerical technique used to perform finite element analysis (FEA) of physical phenomenon.

Through their analysis and experiments, the academics found that the dimensions of the metal ribbon at the back of each cell and the metal coverage ratio of the PCB are key factors for the thermal management of the CPV module, while the other components have a negligible impact on the module temperature.

“The temperature of the solar cell can be kept below 80 C over a wide range of dimensions of the metal ribbon behind the solar cell, both for a metal coverage of the PCB of 0 % or 100 %,” they further explained. “However, this dimensional range is much wider when the metal coverage ratio is 100 % than when the metal coverage ratio on the PCB is 0 %.” The simulation also showed that the temperature of the solar cells may reach 54 C with a copper ribbon and 57 C with an aluminum ribbon.

The system was described in the paper “Finite element modeling and experimental validation of concentrator photovoltaic module based on surface Mount technology,” published in Solar Energy Materials and Solar Cells. “These results demonstrate that in addition to simplifying the assembly process, using SMT for CPV modules fabrication can enhance heat dissipation both by the metallic layer on the glass PCB and on the back side contact,” the researchers concluded. “This opens the door to simpler CPV modules, higher performance CPV modules and higher concentration ratios.”

From pv magazine global

Chinese solar module manufacturer Longi unveiled a new module series based on its proprietary hybrid passivated back contact (HPBC) cell technology.

“Longi’s first-generation BC products were primarily positioned for the rooftop market, but the second generation of BC is entirely different,” the company said in a statement. “The Hi-MO 9 panel is mainly positioned for the ground-mounted utility market.”

The new product is available in eight versions with power output ranging from 625 W to 660 W and power conversion efficiency spanning from 23.1% to 24.4%. The open-circuit voltage is between 53.30 V and 54.00 V and the short-circuit current is between 14.85 A and 15.41 A.

The double-glass modules have a temperature coefficient of -0.28%/C and a maximum system voltage of 1,500. Their size is 2,382 mm x 1,134 mm x 30 mm and their weight is 33.5 kg. They also feature IP68 junction boxes, an anodized aluminum alloy frame, and 2.0 mm coated tempered glass.

The new products come with a 12-year product warranty and a 30-year linear power output warranty, with the 30-year end power output being guaranteed to be no less than 88.85% of the nominal output power.

“In the second-generation BC product, the company has comprehensively optimized the bifaciality issue,” the company said, noting that the bifaciality factor cannot generally be very outstanding in back contact technologies. “However, taking this into full consideration, the overall life-cycle power generation capability we display now an improvement of 6% to 8%,” it added, without providing more details.

The company has not revealed yet all the technical aspects of its HPBC cell technology. It previously said it’s an extension of p-type interdigitated back-contact (IBC) technology that combines the structural advantages of PERC, TOPCon, and IBC solar. Additionally, BC technology can be combined with p-type wafers, for which Longi has substantial production capacities, giving it an advantage over the more common IBC technology.

In March, Longi launched its Hi-MO X6 Explorer and Hi-MO X6 Guardian modules, and last week it introduced the Hi-MO X6 Scientist panel.

The U.S. Department of Energy announced a $38 million funding opportunity via its Solar Energy Technologies Office (SETO), supporting research, development, and demonstration projects related to the solar energy supply chain. 

The funds are intended to support projects that de-risk solar hardware, manufacturing processes, and software products. The funding opportunities also seeks projects that provide outreach, education, or technology development for software that delivers an automated permit review and approval process for rooftop solar and/or energy storage. 

“These investments will help accelerate the growth of the solar industry, identify emerging opportunities, and drive down costs for our domestic energy market, positioning the United States on the leading edge of solar industry advances,” said DOE. 

Eligible technologies include PV, systems integration, concentrating solar-thermal power, technologies that connect solar with storage or electric vehicles. It also considers dual-use projects like agrivoltaics and vehicle-integrated photovoltaics. 

Topic areas: 

1. Solar Research and Technology Development 

DOE will support five to ten projects receiving $1 million to $2 million each. The topic area focuses on R&D projects for for-profit companies improving and de-risking solar components and/or manufacturing processes. Successful project submissions will develop and validate realistic pathways to commercial success. 

2. Solar Energy Demonstration 

Five to ten research, development, and demonstration projects will receive between $1 million and $5 million for established companies or startups to develop pilot-scale or prototype demonstration of solar products. Successful applicants for this topic area will have an existing prototype that requires further testing, engineering work, or demonstration in a controlled environment. 

3. Solar Permitting, Outreach, Education 

One to three projects receive between $1 million to $5 million for outreach, education, and software development activities for automated code-compliant rooftop solar permitting software. The projects are designed for use by solar installers to submit permit applications to local governments and to automate review and approval. 

DOE will hold an informational webinar on the funding opportunity on June 13, 2024. 

Link to Apply: Apply on EERE Exchange 

From pv magazine ESS News site

The energy storage market was worth between $44 billion and $55 billion in 2023, and it’s predicted to reach up to $150 billion by 2030. However, it faces major economic and supply challenges related to the usage of batteries made with scarce and price-volatile materials. How can your company help address these issues?

Eloisa de Castro: Enerpoly develops and manufactures batteries using zinc and manganese as the active materials. The strategic use of globally available and reusable materials plays a significant role in ensuring a stable and reliable supply chain that is resistant to price volatility and geographical constraints. Our zinc-ion batteries rely 100% on a European supply chain, which reinforces their resilience.

Our batteries are environmentally friendly, cost-effective, and safe, and address various large-scale stationary energy storage requirements, including grid stabilization services or reliable backup power. In essence, the attributes of our batteries allow us to provide scalable, reliable and sustainable energy storage solutions.

Enerpoly’s technology meets the affordability, safety, and sustainability demands that are essential for the clean energy transition. Additionally, our recent grant from the Swedish Energy Agency, which will be used to build the world’s first megafactory for zinc-ion batteries, demonstrates that zinc-ion batteries can be affordably and mass-produced at scale.

How did you solve the rechargeability issues typical of zinc-ion batteries?

Enerpoly implemented several key innovations to address these issues. Our zinc-ion batteries use a zinc metal anode and manganese dioxide cathode. We developed strategies that limit inactive manganese species from forming. This is important because manganese oxide could change phase to electrochemically inactive Mn3O4 and cause battery degradation. This innovation significantly enhances both battery performance and rechargeability.

Second, we had to tackle the problem of zinc dendrite formation on the anode. Zinc dendrites can cause short-circuits. We developed a proprietary electrolyte and a controlled battery operation approach to prevent dendrites. Optimization of the battery as a whole must be considered each time there is an innovation to one component, and we have been careful to balance any potential side reactions that can occur with each new modification.

What would the rise of zinc-ion batteries entail for the supply chain and zinc prices?

Zinc is already used in a variety of industrial applications, so an increase in the demand of zinc batteries is unlikely to result in major price fluctuations. Zinc-ion batteries are better insulated from supply chain issues and inflation that have impacted the energy space in recent years. If you look at the zinc prices compared to lithium prices in 2022 and 2023 when commodity prices were the most volatile, lithium had a 14x price volatility and zinc had around 1x.

In addition to that, I expect that the existing recycling of zinc and the extraction of zinc from other important industrial applications creates a more circular supply chain and makes the sourcing flexible, therefore keeping the price quite low and stable. Enerpoly’s focus on zinc, a more stable and less geopolitically constrained material, positions us to appropriately manage any potential cost instability even as demand rises.

How viable is mining and refining of zinc? 

Here’s what is in zinc’s favor: zinc is responsibly and sustainably mined in Europe, and there is 200 times more mining capacity for zinc than there is for lithium in Europe. As for the refined battery-grade materials, Enerpoly uses similar materials as in non-rechargeable zinc-alkaline batteries, and the refining and manufacturing of zinc for European battery manufacturing has been done successfully and reliably for decades by the suppliers of existing European battery giants for the non-rechargeable version of this battery. I cannot say for certain that we will never run into issues, but I have confidence that the chance of coming across major obstacles is very, very low.

Apart from supply chain issues, lithium-ion batteries also carry significant safety risks and face sustainability challenges in their manufacturing and recycling processes. How are zinc-ion batteries different?

Enerpoly’s zinc-ion batteries use no components that can cause thermal runaway, and our zinc-ion batteries, unlike other battery chemistries, are not classified as dangerous goods and are therefore safe for transportation and storage. Some potential positive effects of increased safety include further reduced cost because there is no need for specialized fire suppression components and lower insurance costs, and the ability to deploy in safety-critical applications as well as dense urban areas without the risk of explosions.

Enerpoly’s batteries also use state-of-the-art dry electrode manufacturing and they do not require dry rooms or toxic solvents in production, all of which significantly reduces the energy consumption to manufacture them. Because our batteries use similar materials to the well-established zinc alkaline non-rechargeable battery, there is already an existing recycling infrastructure available for recycling worldwide, further contributing to a decarbonized economy and interestingly, potentially making the batteries even more cost-effective due to lower cost of decommissioning batteries that have fulfilled their lifetime.

To continue reading, please visit our new EES News website.

PV Evolution Labs (PVEL), an independent test lab for the downstream solar industry and member of the Kiwa Group, published its 2024 PV Module Reliability Scorecard. This 10^th edition of the Scorecard names 388 model types of PV modules from 53 manufacturers as Top Performers in PVEL’s testing, the most in the company’s history. Last year the Scorecard named 250 model types among 35 manufacturers.

Kiwa PVEL uses the Product Qualification Program (PQP) to provide the solar industry with empirical data for PV module benchmarking and project-level energy yield and financial modules to identify top performing PV modules.

The PQP was expanded in the fall of 2023 with a new test to address concerns around ultraviolet induced degradation (UVID). It also refocused the hail stress sequence (HSS) on identifying the threshold of glass breakage and modified the mechanical stress sequence (MSS) to target module mechanical durability concerns.

In addition to expanded PQP testing, other updates to the Scorecard include a new Top Performer category for hail, highlighting modules that did not experience glass breakage with ≥40 mm hail, and a higher bar for LID+LETID and PAN Top Performers, with a raised threshold for Top Performer qualification as technologies have improved,

This year’s Scorecard is emphasizing manufacturers who are Top Performers in multiple categories, providing key takeaways on the impacts of various cell technologies and module designs, and offering a deep dive—for the first time– into Kiwa PVEL’s Incidence Angle Modifier (IAM) test results.

“Our 2024 Scorecard showcases strong results across a diverse group of solar module manufacturers, which reflects the excellence and growth we have observed in PV manufacturing in recent years.” said Kevin Gibson, managing director of Kiwa PVEL. “For over a decade, we’ve tested assumptions about solar module reliability and performance while continuing to refine our methodology as the industry continues to innovate with new technologies and module designs. We’re proud that we’re still setting a high bar for manufacturers and providing downstream buyers with the crucial information they need to make educated procurement decisions.”

This partial list shows for which tests each manufacturer achieved Top Performer status with one or more models. Kiwa PVEL noted that in some cases, test results for some test categories were not available at the time of Scorecard publication. Manufacturers are listed by the number of tests, followed by the number of years they have been designated a Top Performer, in alphabetical order. Click here to find model numbers. The full list of Top Performers is a searchable database, where results can be filtered by PQP test, manufacturer name, module type, cell technology, and more.

“With over 50,000 unique visitors to the 2023 edition, our Scorecard is the industry’s go-to resources for module reliability insights. While we applaud the advances in manufacturing and the number of Top Performers listed, we remind buyers to remain vigilant,” said Tristan Erion-Lorico, vice president of sales and marketing at Kiwa PVEL. “We encourage them to explore each page of the Scorecard to better understand the range of test results that we’re seeing every day at Kiwa PVEL’s labs.”

Notable in this year’s test results is that 66% of module manufacturers experience at least one test failure, which Kiwa PVEL said is the highest percentage ever reported.

With the extreme weather events wreaking havoc on some solar installations in recent months, the new Top Performer category for hail shines a spotlight on how the hail testing is performed. Kiwa PVEL focuses almost exclusively for 2.0 mm glass//glass and 3.2 mm glass//backsheet, but results showed that three tested BOMs of 2.5 mm glass//glass showed no glass breakage with 50 mm hail. Kiwa PVEL noted that while glass breakage typically is not considered a Scorecard “failure,” some manufacturers required multiple retests of the same hail diameter before achieving the desired hail test performance, and three manufacturers had modules where the junction box lid fell off due to hail impacts.

To be eligible for the 2024 Scorecard, manufacturers must have completed the PQP sample production factory witness after October 1, 2022, and submitted at least two factory-witnessed PV module samples to all PQP reliability tests, as per Kiwa PVEL’s BOM test requirements.

Kiwa PVEL, a testing lab for downstream solar project developers, financiers, and asset owners around the world, is part of the Kiwa Group.

Access the Scorecard here.

An international research team has developed a method to make high-quality perovskite films at room temperature for applications in perovskite solar cells. The novel process avoids thermal annealing and additional post-treatments.

The team selected a perovskite composition known as (Cs_x(FA_0.92MA_0.08)_1−xPb(I_0.92Br_0.08)₃), which was converted into α-FAPbI₃ at room temperature. Further conversion was promoted with the addition of an organic linker known as oleylamine or simply OAm. The method’s effect on quality growth patterns was confirmed by in situ X-ray monitoring.

Furthermore, to demonstrate the feasibility of the process on non-traditional PV substrates and materials, the researchers deposited their perovskite film on a plant leaf, something that would have been impossible with conventional methods.

“The most challenging aspects of the work were to understand the working mechanism and then to demonstrate that the process was gentle enough to deposit perovskite films atop fresh leaves which are very soft and fragile,” research lead author, Thuc-Quyen Nguyen, told pv magazine.

The researchers described the fabrication of cells with a planar p-i-n structure to investigate the effect of cesium (Cs) and OAm on performance and said they used only printable materials. The fabricated devices had an indium tin oxide substrate with a spin-coated layer of MeO-2PACz, which is also known as [2-(3,6-Dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid.

Then the perovskite absorber went through a two-step spin-coating process and was connected to an electron transport layer (ETL) based on  phenyl-C61-butyric acid methyl ester (PCBM) that also relied on spin coating and a bathocuproine (BCP) buffer layer. All of the previous was achieved without thermal annealing. Finally, a 100 nm thick silver metal contact was thermally deposited onto the substrates as cathodes inside a vacuum thermal evaporator.

Reproducibility was assessed via 100 devices with varying amounts of experimental materials. Observing the results, the team noted that the addition of OAm “significantly mitigated” deviations and improved device properties, and that the Cs10+OAm devices exhibited the highest short-circuit current density, open-circuit voltage, and fill factor with the smallest deviations of efficiencies.

The team said that the optimized Cs_10+OAm device achieved “impressive efficiencies” of 23.2%. With an anti-reflective coating, it was increased to 24.4%. It noted that the results surpassed efficiencies attained by previous low-temperature and room-temperature (RT) processed perovskite solar cells (PSCs).

“Through a combination of characterization techniques, we unveiled the morphology and device physics of RT-processed PSCs. Finally, we demonstrated that the annealing-free processing enables the fabrication of high-quality perovskite films on leaf substrates,” concluded the researchers.

The details of the study appear in “Room-temperature-processed perovskite solar cells surpassing 24% efficiency,” published in Joule. The researchers came from three institutions, University of California, Santa Barbara, Korea’s Pusan National University, and Korea Electric Power Research Institute.

Looking ahead, the teams intend to work on integrated PV and indoor PV technologies. “Currently, we focus on the development of efficient semi-transparent solar cells that achieve efficiencies exceeding 12% while ensuring a transparency level of over 30%. These cells are designed for integration into building windows, vehicles, and greenhouses,” said Nguyen.

“Additionally, we are actively engaged in the development of indoor solar cells capable of achieving efficiencies surpassing 40% under LED lighting conditions. This breakthrough has the potential to provide renewable energy to power indoor devices and systems.”

PVRadar offers solar project risk assessments factoring in historical climate data  PVRadar Labs has expanded its software platform to include PV project risk assessment functionality, reportedly enabling more realistic performance estimates based on historical climate data.

JinkoSolar claims 33.24% efficiency for perovskite-silicon tandem solar cells JinkoSolar says it has achieved a 33.24% efficiency rating for its perovskite-silicon tandem solar cells, confirmed by the Shanghai Institute of Microsystem and Information Technology under the Chinese Academy of Sciences (CAS).

Vermont becomes first state with Climate Superfund Act  The Vermont legislation intends to hold fossil fuel corporations responsible for climate change.

Fronius unveils residential string inverter for rooftop solar The Fronius Gen24 hybrid inverter comes to North America after success in Europe.

Solar project developers face opposition from Joshua Tree conservationists  The site of the Aratina Solar Center in Kern County, California, is home to western Joshua trees, and therefore the developer has to comply with the Western Joshua Tree Conservation Act that was enacted in July 2023. Incidental Take Permits authorize renewable energy developers to remove trees with an option to pay a standard mitigation fee rather than complete mitigation actions.

Texas to host 300 MW of geomechanical energy storage projects  Quidnet Energy, a provider of geomechanical energy storage (GES) technology, has joined hands with distributed energy resources developer Hunt Energy Network to deliver 300 MW of storage projects in the Electric Reliability Council of Texas (ERCOT) grid operating region.

Tandem PV, a perovskite solar panel developer, announced it has secured a $4.7 million award from the U.S. Department of Energy (DOE) Solar Energy Technologies Office to advance commercialization of its thin-film solar technology.

The award is part of a larger $71 million investment by DOE in projects that support bolstering the U.S. solar supply chain.

The company develops solar panels that pair conventional silicon cells with perovskite materials for panels, giving them the potential to produce up to 40% more power than traditional solar modules used today, said Tandem PV.

Tandem PV’s design stacks a thin-film perovskite layer on top of the crystalline PV layer, with the two materials absorbing different wavelengths of sunlight. The company is currently producing tandem perovskite panels with about 26% efficiency, which is roughly 25% more powerful than a conventional silicon solar panel today.

Solar panel efficiency is an important metric for solar facility developers. More power at a similar price per watt leads to lower labor costs for installation, lower land-acquisition costs, and a lower total cost of ownership for customers, said the company.

“This is Tandem PV’s 10th award from the Department of Energy and we are grateful for its consistent, long-term investment and validation,” said Tandem PV co-founder and chief technology officer Colin Bailie.

The company said its has demonstrated “the equivalent of decades of projected durability” in the lab. Durability has been a key issue to solve for perovskites, which show high efficiencies, but degrade rapidly in the field.

Tandem PV said it plans to obtain independent industry-standard validations of the durability and efficiency of its perovskites during 2024. The company said plans are underway for a first manufacturing facility as research and development efforts advance.

“Thanks to historic funding and actions from the president’s clean energy agenda, we’re able to deploy more solar power – the cheapest form of energy – to millions more Americans with panels stamped ‘made in the U.S.A.’,” said Jennifer M. Granholm, U.S. Secretary of Energy.

Tandem PV, founded in 2016 in Silicon Valley, has raised a total of $33 million in venture capital and government funds including from the DOE, the National Science Foundation and the California Energy Commission.

Tandem PV was selected for the $4.7 million award as part of SETO’s Advancing U.S. Thin-Film Solar Photovoltaics Funding Program.

From pv magazine Global

Chinese solar module producer JinkoSolar said it has achieved a 33.24% power conversion efficiency for a perovskite-silicon tandem solar cell based on n-type wafers.

The company said the results have been certified by the Shanghai Institute of Microsystem and Information Technology under the CAS. In its previous attempts, JinkoSolar achieved a cell efficiency of 32.33% for the same device configuration.

“This breakthrough in conversion efficiency for the perovskite/TOPCon tandem solar cell has been achieved through various materials and technology innovations including ultra-thin poly-Si passivated contact technology, novel light-trapping technology, intermediate recombination layer with high light transmittance and high carrier mobility, and efficient surface passivation technology using hybrid materials,” the manufacturer said, without providing any additional technical details.

Researchers from Germany’s Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE) recently said that the practical power conversion efficiency potential of perovskite-silicon tandem solar cells could reach up to 39.5%. Researchers said exceeding this efficiency threshold requires a change in cell architecture, replacing buckminsterfullerene (C60) with a more transparent electron transport layer, and finding more transparent alternatives to indium tin oxide (ITO) layers.

Researchers at the University of Illinois Chicago (UIC) have developed a new method to make hydrogen gas from water using solar power and agricultural waste like manure or husks. The researchers said the method reduces the amount of energy needed to create hydrogen fuel by 600%. The results are published in  Cell Reports Physical Science.

The method uses a carbon-rich substance called biochar to decrease the amount of electricity needed to convert water to hydrogen. Combined with using solar power or wind to power the water-splitting process known as electrolysis.

“We are the first group to show that you can produce hydrogen utilizing biomass at a fraction of a volt,” said Singh, associate professor in the department of chemical engineering. “This is a transformative technology.”

Electrolysis represents the most expensive step in the hydrogen fuel lifecycle, representing about 80% of the cost. Recent advancements in producing hydrogen fuel have decreased the voltage required for water splitting by introducing a carbon source to the reaction. However, this process often uses coal or expensive refined chemicals and releases carbon emissions as a byproduct.

The UIC researchers modified the process to instead use biomass from common waste products as the carbon source. By mixing sulfuric acid with agricultural waste, animal waste, and sewage, they produced a slurry of biochar to be used in the reaction.

The team trialed several different inputs for biochar, including sugarcane husks, hemp waste, paper waste, and cow manure. All five inputs reduced the power needed to perform electrolysis, but the best performer, cow manure, decreased the electrical requirement by 600%, to roughly a fifth of a volt.

With reduced voltage requirements, the UIC researchers were able to produce an electrolysis reaction with one silicon solar cell generating about 15 milliamps of current at 0.5 volt, or less than the amount of power produced by a AA battery.

“It’s very efficient, with almost 35% conversion of the biochar and solar energy into hydrogen” said Rohit Chauhan, the report’s co-author. Chauhan said the utilization rate of biochar represents a world record.

The research team said this utilization for biochar represents a new revenue stream potential for farmers, or an opportunity to become self-sustainable for energy needs.

Orochem Technologies Inc. sponsored the research and has filed for patents on the biochar-hydrogen process. The UIC team plans to test the methods at a larger scale. Stanford University, Texas Tech University, Indian Institute of Technology Roorkee, Korea University also participated in this study.

Strategies to address thermomechanical instability of perovskite solar modules  A U.S. research team has investigated the thermomechanical reliability of metal halide perovskite (MHP) modules and cells in an effort to identify the best strategies to improve their stability under thermomechanical stressors. The scientists discussed, in particular, film stresses, adhesion of charge transport layers, and instability under light and heat.

From pv magazine 05/24

On Jan. 31, 2024, researchers from the Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE) announced that, alongside perovskite developer Oxford PV, they had produced a full-sized perovskite tandem module with a conversion efficiency of 25%. At 421 W, the dual-glass module’s power output is far from that achieved by the large-format modules manufactured by solar industry giants. Nonetheless, the result was a powerful demonstration of the steps being made toward commercializing what is widely considered the next generation of solar cell technology.

When announcing the result, the Fraunhofer ISE team noted that scientists from its CalLab PV Modules’ calibration laboratory used a “multispectral solar simulator” to measure both the crystalline silicon solar cell and perovskite cells. It allowed for different light spectra to be applied to the cell while under continuous illumination. This required specialized measurement equipment based on LED light sources that were able to provide illumination evenly across the module’s 1.68 m² surface.

“The continuous intensity and spectral stability of the light source is of particular importance especially for tandem devices,” said Johnson Wong, general manager for the Americas at equipment provider Wavelabs. The researchers from Fraunhofer ISE used Wavelabs’ Sinus-3000 Advanced LED module I-V tester for the Oxford PV module.

“Thanks to its optimized light distribution over a long working distance, the tester light source is designed to cast a light field that very closely mimics the sun at every point over the large module area,” Wong added. He said the Sinus-3000 LED tester exceeds A+ class in terms of “spectrum, light uniformity, and stability over time, which play a critical role in the measurement accuracy.”

Accurate characterization

The accurate characterization of perovskite solar devices requires not only new equipment but also novel processes. Longer illumination times are needed; the temperature impact of the light source must be controlled or corrected for; I-V sweeps should be significantly slower than in crystalline silicon cells; and, in tandem cells, their current must be aligned so that the combined power output is not limited.

The PV research community, prospective manufacturers, and equipment suppliers are making strides in overcoming the formidable challenges posed by perovskite solar devices. New, collaborative research projects are being launched and measurement routines are becoming more sophisticated. As a result, confidence is growing that as the prospective PV perovskite manufacturers develop their devices toward maturity, the equipment and processes will be ready.

Sunny prospects

Karl Melkonyan, PV technology analyst with S&P Global Commodity Insights, said that perovskite tandems have “the best chances for commercialization” among next-generation solar cell technologies. Perovskite PV cells can be coupled with either crystalline silicon (c-Si) or thin-film solar cells.

Early perovskite PV devices achieved conversion efficiencies in the low single digits – 3.8% was recorded in 2008. Record efficiencies are now set at regular intervals and are well beyond 25%.

Perovskite tandem devices are extremely promising, primarily because the thin-film perovskite cell plus the “base” c-Si, cadmium telluride, or copper indium gallium selenide layer can capture different light wavelengths, resulting in small-scale research cells with efficiencies beyond 30%.

Translating lab efficiency to larger cells and modules is difficult, however. “While there are many record efficiency achievements of perovskite solar cells reaching 20% and above, the total efficiency of a tandem structure can be much lower than the sum of those individual efficiencies,” said Melkonyan. He noted that the reason for this is often a current mismatch between bottom and top cells.

Measurement challenges

For a PV device to prove its worth, its power output must be able to be measured in a highly accurate, replicable, and standardized fashion. At the end of the day, if a PV module is to be purchased and installed, it is vital that its nameplate power output can be trusted.

Here, as noted in the recent Fraunhofer ISE and Oxford PV result, perovskite PV devices present a host of new challenges. “Yes, the power measurement of a perovskite tandem or multi-junction cell presents challenges and could be quite difficult because very specific spectrally-adjustable solar simulators are required,” said Melkonyan. “Apart from appropriate stabilization methods for different perovskite materials, the processes should include standardized protocols to measure under standard test conditions.”

In late April 2024, Fraunhofer ISE, Oxford PV, Wavelabs, and the University of Freiburg wound up an 11-month investigation into how large-format perovskite tandem PV cells can be accurately characterized. Fraunhofer ISE’s Martin Schubert led the project – abbreviated to “Katana” in German. He said there are two major differences between the characterization of perovskite tandem devices and regular PV modules.

Two factors

“One is that the efficiency may change during illumination,” said Schubert, who leads the quality assurance, characterization and simulation team. “The reason for that is that there is an ion migration in the perovskite cell in which some ions are moving. The second complication is the tandem architecture. By itself, that means we have two solar cells – one on top of the other and with different spectral sensitivity. We need to take care that the top cell gets the right amount of current and the bottom cell gets the right amount of current.”

Ion migration within the perovskite device while under continuous illumination means that the measured efficiency can either increase or decrease over time. This “metastability” necessitates the long illumination time needed for stabilized power output to be ascertained. Complicating things further, different perovskite PV compositions demonstrate varying levels of metastability.

The need for long light exposure, to accommodate metastability, brings heat, even when using LEDs. This means that the measurement of perovskite devices is often carried out at temperatures higher than standard test conditions (STC).

The power output of a photovoltaic device declines as its temperature increases, a factor described as a device’s temperature coefficient. Different PV technologies mean differing temperature coefficients. c-Si solar products, for example, have a larger temperature coefficient than thin film devices. If that is not controlled and accounted for, the result is measurement uncertainty.

Testing equipment with temperature control – essentially a chamber with air conditioning – can reduce this uncertainty in best-case scenarios. Such sophisticated devices, particularly with sufficient scale to accommodate full modules, come at a cost.

The impact of temperature can be corrected for using mathematical models based on accurate temperature readings and can account for the uncertainty higher temperatures can bring. With tandem devices, the temperature sensitivity of both the top and bottom cell must be accounted for – a complex, if not impossible, equation.

Commercial implications

At present, the testing of perovskite devices is carried out within minutes, to account for metastability related to ion migration in the perovskite cell, so that slower I-V sweeps, with multiple power point tracking (MPPT), can be carried out. This is unsuitable for mass production, as many modules need to be rolling off production lines every minute.

Wavelabs’ Wong said that a “more pragmatic test routine” would likely first involve a preconditioning of the module using light soaking, from mass-production light sources. That could then be followed by “a fast I-V sweep using high quality illumination that must fit within the specifications of spectral match, uniformity, and stability,” said Wong. “The fast I-V sweep will likely be done in the order of 100 milliseconds to one second, during which the ions are ‘frozen in’ to their preconditioned distribution and do not significantly redistribute.”

Fraunhofer ISE will be launching a three-year research project in May 2024 that will investigate how “fast and precise measurements” can be developed and executed for perovskite devices, including tandems. The project, abbreviated to “PERLE” in German, will be funded by Germany’s Federal Ministry of Economic Affairs and Climate Action. Fraunhofer ISE’s Schubert said that it is possible that the first findings from the project will be published by May 2025.

From pv magazine Global

Thermophotovoltaics (TPV) is a power generation technology that uses thermal radiation to generate electricity in photovoltaic cells. A TPV system generally consists of a thermal emitter that can reach high temperatures, near or beyond 1,000 C, and a photovoltaic diode cell that can absorb photons coming from the heat source.

The technology has drawn the interest of scientists for decades, because it can capture sunlight in the entire solar spectrum and has the technical potential to beat the Shockley-Queisser limit of traditional photovoltaics. However, the efficiencies reported thus far have been too low to make it commercially viable, as TPV devices still suffer from optical and thermal losses.

With this in mind, a group of researchers at the University of Michigan in the United States have developed TPV cells that reportedly address these issues and achieve a power conversion efficiency of 44%.

“This level of efficiency could enable thermal battery systems to reach a price point needed to put most of the grid on wind and solar power,” said research’s lead author, Andrej Lenert, told pv magazine. “Such systems have to continuously draw energy from a hot storage material such as graphite as it cools from its maximum allowable temperature. Getting 40% efficiency at storage temperatures as low as 1300 C, versus requiring 2000 C as previously, means these batteries could possibly get twice as much energy per kg of graphite.”

According to Lenert, this result represents a major improvement in TPVs and solid-state heat-to-power generation at large. “It is a culmination of several years of intense research to understand how to minimize energy losses and mechanical issues in air-bridge TPV cells, which we originally reported in 2020,” he added. “Those cells were 32% efficient and relatively fragile, now we are closer to 44% and have a much more robust technology. Though still not at the kW or MW scale, this result demonstrates what is possible with single-junction TPV cells, fulfilling decades-old theoretical predictions made by the TPV community.”

In the study “High-efficiency air-bridge thermophotovoltaic cells,” which was recently published in Joule, Lenert and his colleagues described the cell as an air-bridge indium gallium arsenide (InGaAs) device that can absorb most of the in-band radiation to generate electricity. It can also serve as a nearly perfect mirror, with almost 99% reflectance.

The cell was built with a silicon substrate, an air bridge structure with a thickness of 570 nm, a rear contact made of gold (Au), titanium (Ti), an n-doped InGaAs layer, a membrane layer with a thickness of 1 µm, an InGaAs absorber, and a front contact made of Au, Ti, platinum (Pt), and p-doped InGaAs. Three different absorber layers were tested with energy bandgaps of 0.74 eV, 0.90 eV, and 1.1 eV, respectively. 

The air-bridge layer is embedded between the three active layers and the rear Au mirror to enhance backside reflectance and recovery of out-of-band photons. The membrane support layer is intended to minimize buckling of the free-standing semiconductor membrane and ensure a single cavity mode within the air layer.

“The combination of a nanoscale air layer and a relatively high coverage of conductive rear electrodes ensures that the air-bridge thermal resistance is small compared with that of the Si substrate,” the scientists emphasized. “Additionally, the design includes a membrane support layer to minimize buckling of the free-standing semiconductor membrane and ensure a single cavity mode within the air layer.”

The researchers found that the cell with an absorber bandgap of 0.90 eV achieved the best performance. It reached a power conversion efficiency of 43.8% at 1,435 C. “It surpasses the 37% achieved by previous designs within this range of temperatures,” Lenert stated. “We’re not yet at the efficiency limit of this technology. I am confident that we will get higher than 44% and be pushing 50% in the not-too-distant future,” added research co-author, Stephen R. Forrest.”

These results, according to the research group, also promise significant improvements in the device’s round-trip efficiency. “It’s a form of battery, but one that’s very passive. You don’t have to mine lithium as you do with electrochemical cells, which means you don’t have to compete with the electric vehicle market,” Forrest further explained. “Unlike pumped water for hydroelectric energy storage, you can put it anywhere and don’t need a water source nearby.”

A new bladeless wind energy unit, patented by Aeromine Technologies, has secured $9 million in Series A funding to accelerate the roll-out of its innovative technology. The scalable, “motionless” wind energy unit can produce 50% more energy than rooftop solar at the same cost, said the company.

Aeromine’s technology is primarily designed for installation on the edge of a large rooftop like an apartment building, a big box store, factory or warehouse, facing the predominant wind direction. The technology leverages aerodynamics like airfoils in a race car to capture and amplify each building’s airflow. The unit requires about 10% of the space required by solar panels and generates round-the-clock energy, as long as the wind is blowing.

Veriten, an energy research, investing, and strategy firm led the funding round, with participation from Thornton Tomasetti. The company said it has received nearly 11,000 inquiries from more than 6,500 companies and currently has a pipeline of 400 qualified projects. Its customers are primarily in industrial, logistics, automotive, commercial, and government sectors.

Aeromine said unlike conventional wind turbines that are noisy, visually intrusive and dangerous to migratory birds, the patented system is visually motionless and virtually silent. And unlike large centralized onshore and offshore wind farms, the space efficient systems are mounted on roofs, bringing power closer to where it is needed, and lessening the need for expensive long-distance transmission infrastructure.

“Distributed power is a key and increasingly strategic element to an evolving ‘all the above’ energy mix,” said Maynard Holt, founder & chief executive officer of Veriten. “We believe that distributed power innovation will play a vital role in helping companies fulfill their need for reliable, reasonably priced electricity and desire for low-impact power.

Each unit weighs just over 1,000 lbs., can withstand winds of 120 mph and can be upgraded to hurricane-resistant models that withstand winds up to 158 mph. The Aeromine generator system is a state-of-the-art rotor / stator system with a 5 kW permanent magnet generator. Product specifications can be found here.

A typical installation would connect 10 units or more, adding 50 kW of capacity to a roof. A ten-unit 50 kW system’s electricity generation varies widely. Aeromine said a roof height of 16 feet and 4.5 meters per second average wind speed would produce about 20,000 kWh per year, while the same 10-unit system on a 50-foot-high roof with 8 meters per second average wind speed would produce over 150,000 kWh per year.

Aeromine told pv magazine USA that “pricing is in line with comparatively rated roof top commercial solar power systems.” The company expects to introduce a commercial solution into the European and North American markets in 2025.

“Aeromine’s proprietary technology brings the performance of wind energy to the onsite generation market, mitigating legacy constraints posed by spinning wind turbines,” said Aeromine chief executive officer David Asarnow.

From pv magazine Global

It is estimated that there will be more than 1,675,000 distributed renewable generation inverters connected to electrical grids around the world in 2030. But there is an element associated with these devices that is often overlooked and that is key to a stable grid – harmonics.

In DC/AC inverter-based systems, such as solar and storage, the injection of total harmonic distortion (THD) into the grid can be very detrimental to the generation plant and the grid as a whole. THDs are triggered by variations in solar irradiance and temperature as well as by the use of the inverters themselves, a major source of harmonics due to constant switching on and off.

There are several techniques to reduce the THD at the output of the inverters. In the case of photovoltaic stations composed of several inverters that operate in parallel, phase shifting is the most used. With this technique, the switching signals of all inverters are shifted slightly so that the harmonics due to switching cancel each other out. The result is that the THD of the entire plant is lower than that generated by the individual inverters.

Beyond the immediate impact on power production, harmonics can trigger mechanical vibrations, thereby compromising the longevity of critical components such as transformers. Furthermore, poor antiharmonic strategies can lead to the deterioration of the performance and efficiency of entire systems.

The use of so-called “Ultra-low THD inverters” minimizes the harmful effects of harmonic distortion and avoids not only the hidden losses that occur in the installation, but also the associated reliability and performance problems caused by harmonics. This is the main conclusion of “Unlocking the hidden benefits of ultra-low THD inverters in solar and storage projects,” a white paper that was recently published by Gamesa Electric, a Spanish manufacturer of renewables equipment.

The white paper includes an independent study that compares the performance of an Ultra-low THD inverter, such as the Gamesa Electric Proteus, against other models with a lower capacity to attenuate harmonics. It concludes that, in the case of the Gamesa Electric Proteus, production can be up to 0.35% higher.

“Harmonic distortion or THD is one of the most forgotten sources of losses and reliability problems in solar and storage plants,” said Gamesa Electric Technology Director Andrés Agudo.

As explained in the white paper, inverter design standards are obsolete and compliance with them does not ensure that these problems are avoided.

“It is necessary to design what we call Ultra-low THD inverters, like our Gamesa Electric Proteus model, to minimize losses, which can be very significant, as the study shows,” said Agudo.

From pv magazine Global

The Durable Module Materials (DuraMAT) consortium, established by the United States Department of Energy’s Solar Energy Technology Office (SETO), has released its latest annual report with news about the availability of new PV forecasting tools and new research about certain module degradation trends.

DuraMAT reported the results of its focus on reliability forecasting in 2023, driven by the observation that the PV industry is “innovating so quickly that the performance of modules in the field is no longer always a reliable indicator of what will happen in the future.”

“We awarded six projects under our reliability forecasting call this year,” said Teresa Barnes, DuraMAT director and DOE National Renewable Energy Laboratory (NREL) researcher in a press release.

The reliability forecasting projects addressed ultraviolet-induced degradation, glass fracture mechanics, and degradation mechanisms in encapsulants, as well as how to do faster analysis of failure data. As a result, DuraMAT now has a suite of software tools and data sets, some of which rely on quantitative modeling and rapid validation technologies. The tools cover topics such as mechanical models for materials, wind loading, fracture mechanics, moisture diffusion, and irradiance, and are available in the DuraMAT Data Hub.

“Drawing insights from all these areas should give us the capability to predict the long-term reliability of new module designs,” stated Barnes.

Two degradation mechanisms that received special attention from DuraMAT in 2023 are cell cracking and ultraviolet (UV) degradation. “Cracked cells are a challenge for the solar industry because they can reduce output but often go unnoticed,” said the team. Studies were carried out on quantifying and addressing cell cracking.

“Researchers found that some newer modules with many busbars, half-cut cells, and glass–glass encapsulation are more tolerant of cracked cells and less likely to show power loss,” it said. An outcome of the research is WhatsCracking, a free cell fracture prediction application to assist in making modules that are less sensitive to cell breakage. For example, designing modules that rotate half-cells at 90-degree angles to reduce the chance of cracking under load, as reported in pv magazine. The WhatsCracking app is one of the tools in the DuraMAT Data Hub.

DuraMAT researchers also found that UV-induced degradation is a significant issue in certain high-efficiency products. “These results are important, as the increased degradation related to UV exposure in modern cell types may offset some of the gains predicted from bifacial and other high-efficiency cells,” said the team, adding that DuraMAT will be starting new work to quantify this type of degradation in 2024.

The DuraMAT consortium, which is led by the DOE’s National Renewable Energy Laboratory (NREL), with participation by Sandia National Laboratories and Lawrence Berkeley National Laboratory, includes a 22-member board of solar industry professionals.

From pv magazine Global

A research group at the University of Toledo in the United States has designed a four-terminal (4T) tandem solar cell with a top device relying on a perovskite absorber with a tunable wide-bandgap and a bottom cell using a commercially established narrow-bandgap absorber technology made of cadmium telluride (CdTe).

“While a lot of work has been done on perovskite-silicon, perovskite-CIGS, and perovskite-perovskite tandem cells, perovskite-cadmium telluride tandem solar cells are relatively unexplored,” the scientists said. “Although the efficiency potential of CdTe-based tandems is likely lower than CIGS-based tandems due to the higher bandgap of the CdTe bottom cell, the broader commercial success of CdTe solar cells makes them a point of interest in investigating thin-film tandem applications.”

The academics said a key element of the solar cell is the transparent back contact (TBC) technology used for the top tunable wide-bandgap perovskite cell. For the construction of these contacts, they used indium zinc oxide (IZO) as an alternative to well-established indium tin oxide (ITO).

They prepared the IZO films through the radio frequency (RF) magnetron sputtering technique, which is an approach involving alternating the electrical potential of the current in a vacuum environment at RFs.

They also explained that their efforts were aimed at identifying the ideal IZO thickness, as this plays a crucial role in improving the performance and optical transmittance of the semitransparent perovskite top cell by increasing the perovskite bandgap allowing more long-wavelength photons to transmit and enter the CdSeTe bottom cell. In turn, this compensates for a typical optical loss factor in a 4T tandem configuration.

The top cell was constructed with a substrate made of glass and indium tin oxide (ITO), a hole transport layer (HTL) made of nickel(II) oxide (NiOx), a layer made of a phosphonic acid called methyl-substituted carbazole (Me-4PACz), the perovskite absorber, an electron transport layer (ETL) relying on buckminsterfullerene (C60), a tin oxide (SnOx) buffer layer, and the IZO back contact.

The bottom cell was designed to have a substrate made of glass and ITO, an ETL made of tin oxide (SnO2), a cadmium telluride (CdTe) absorber, a cadmium selenium telluride (CdSeTe) layer, a copper thiocyanate (CuSCN) HTL, and a gold metal contact.

Both cells were covered with an anti-reflecting coating.

The best tandem cell configuration was achieved when the absorber of the top cell was tuned to have an energy bandgap of 1.76 eV. With this value, the device reached an overall power conversion efficiency of 25.1%.

The top cell was found to achieve an efficiency of 17.93%, an open-circuit voltage of 1.315 V, a short-circuit current of density of 17.11 mA cm², and a fill factor of 79.7%. The bottom cell showed an efficiency of 7.13%, an open-circuit voltage of 0.842 V, a short-circuit current of density of 11.15 mA cm², and a fill factor of 76.0%.

“The result proves the concept that 4T perovskite–CdSeTe tandem configuration can be used to improve the efficiency of commercial CdSeTe thin-film solar cells,” the researchers stated, adding they are currently outlining a roadmap to increase the device’s efficiency to 30%. “Our analysis reveals that high-efficiency 4T perovskite–CdSeTe tandem solar cells are feasible with the future advance of both PV cells.”

The details of the new cell design can be found in the study “Four-Terminal Perovskite–CdSeTe Tandem Solar Cells: From 25% toward 30% Power Conversion Efficiency and Beyond,” which was recently published in RRL Solar.

The University of Toledo developed several types of CdTe solar cells over the past years. The devices include, among others, a 20%-efficient cell based on a commercial tin(IV) oxide (SnO₂) buffer layer, a 17.4%-efficient device using a layer of copper-aluminum oxide to the rear side of the CdTe thin film, and a solar cell based on an indium gallium oxide (IGO) emitter layer and a cadmium stannate (CTO) transparent conductor as the front electrode.

A recent report by the International Energy Agency said lithium-ion batteries remain the key storage technology for the energy and transportation sectors. While mining for lithium is keeping pace with increasing demand, lithium refining and production of battery packs is concentrated in China, which causes some concerns in the West over supply chains and market dominance.

Sodium is emerging as a viable material for solid state batteries for many of the same energy storage applications that now favor lithium-ion systems.

Bor Jang, chief science officer and board chairman of Solidion Technology, an Ohio-based developer of solid battery technologies, told pv magazine USA that as many countries become dependent on batteries for important sectors of their economies, they will be prompted to search for alternative formulations to those based on lithium, which is relatively rare.

“Sodium, by contrast, is much more abundant in the Earth’s crust and oceans and is evenly distributed around the world,” he said.

In addition to its abundance, which leads to lower costs and easier supply chains, sodium-ion formulations have advantages in faster recharge rates and improved fire safety over lithium-ion ones, Jang said. The tradeoff is that sodium-ion batteries have less energy density (watts per kilogram), which translates into shorter ranges for electric vehicles and less overall storage capacity for grid operators for the same footprint.

However, Jang said, sodium-ion batteries are perfectly suited to EV uses where a 150-mile range would not be a burden, such as for local utility fleets or commuter driving, and where their faster recharge cycles would be appreciated, as would the projected lower price. Similarly, grid-storage facilities where footprint is not an issue would benefit from recharge rates and fire safety characteristics.

On the manufacturability side, Jang said sodium-ion batteries could be produced in factories that currently make lithium-ion batteries with only minor changes to the equipment.

“Solium-ion batteries have the potential to be useful across a wide range of applications, not just those dominated by lithium-ion technology” Jang said. “They can be used in place of lead-acid batteries, for example. Such demand will bring down prices.”

A materials scientist by education, Jang said he turned his attention to solid-state battery research and development about 20 years ago as the needs of the proposed energy transition from fossil fuels to non-emitting sources clearly would require a dramatic increase in energy storage capacity, particularly with renewable generators such as solar and wind. He founded a number of companies focused on the supply of materials for solid state battery electrolytes, anodes and cathodes.

Earlier this year, he saw the merger of his Honeycomb Battery Co. with Nubia Brand International Corp. which gave Solidion status as a publicly traded company. It joins a number of competitors hoping to commercialize sodium-ion batteries.

Jang said Solidion is working with the U.S. Department of Energy through one of the national laboratories, not announced, and the University of Texas, Austin, to improve the performance of sodium-ion battery technology. In particular, the focus is on improving the energy density electrolyte and replacing expensive cobalt and nickel in battery components.

From pv magazine Global

Chinese solar module manufacturer Longi has achieved a power conversion efficiency of 27.30% for an HBC solar cell. Germany’s Institute for Solar Energy Research (ISFH) has confirmed the result.

The new efficiency record beats the previous world record of 27.09%, which was also set by Longi at the end of last year.

At the time, Longi said the result was enabled through a new laser graphical process that costs less than conventional high-cost photolithography processes.

“This substitution has effectively reduced the cost of the BC cell,” the company said in a statement, noting that the HBC architecture also minimizes the reliance on traditional indium-based transparent conductive oxide (ITO). “This breakthrough has propelled the commercialization of HBC solar cells, featuring independent intellectual property and cost-effectiveness.”

In early November, Longi announced a power conversion efficiency of 33.9% for a perovskite-silicon tandem solar cell.

It claimed the world’s highest efficiency for silicon cells in November 2022, with a 26.81% efficiency rating for an unspecified heterojunction solar cell.

From pv magazine Global

A global group of scientists led by the Massachusetts Institute of Technology (MIT) developed a novel low-cost solar-powered brackish water desalination system that can reportedly reduce the levelized costs of water (LCOW) compared to conventional PV-driven desalination systems.

The proposed desalination system utilizes time-variant electrodialysis reversal (EDR) technology, which the researchers developed as a flexible variation of traditional EDR desalination. “Our research aims to address water scarcity in rural India where the majority of underground water is too saline to drink. The grid electricity access and stability are not good, suffering from frequent power cuts,” corresponding author, Wei He, told pv magazine.

“An EDR module is made up of a stack of ion exchange membranes and uses an electric field to move ions from the dilute flow channels to the brine flow channels between each membrane,” said the research group. “This electric field can be intermittently reversed to prevent the build-up of scale on the membrane.”

However, due to solar energy’s intermittent nature, the classic EDR is not a perfect fit. It requires constant power for its operation, and therefore, PV-EDR plants need the support of batteries or oversized solar systems, particularly at the start and end of the day when solar power is low.

“To overcome these problems, we have developed a flexible batch EDR technology that incorporates a time-variant voltage and flow rate adjustment,” the academics explained. “A model-based control method enables the EDR system to align its power consumption with available solar power at each time step while optimizing water production under varying solar conditions.”

To control the operation, the team created a feed-forward, model-based main controller running in Python to compute the optimal pump flow rate and the EDR stack voltage based on real-time sensor readings. A prototype was built at a research facility, closely reflecting the typical design parameters and operational conditions for a community-scale PV-EDR system sized to produce 6 m3 freshwater per day. It was powered by a solar panel with an area of 37 m2 and a tilt of 30 degrees.

This pilot system was tested for single-day and six-day analysis and compared to the traditional constant-operation EDR system. Both systems were fed with water with an average starting salinity of 970 mg l−1. The system was set at a conservatively low water recovery ratio of 60%.

“The flexible system is able to directly use 77% of the available solar energy on average compared with only about 40% in the conventional system (a 91% increase),” the scientists emphasized. “This suggests that a conventional system would require much more solar panel area to operate directly (that is, without any energy storage), increasing capital costs.”

In addition, the analysis showed that the average minimum battery capacity required for the flexible system was 0.27 kWh, a 92% reduction compared to 3.3 kWh in the constant system. “Finally, the results show that the flexible system can reach its production volume up to 54% faster than the conventional system,” they added.

Following the experimental results, the researchers conducted a cost analysis case study for the usage of such a system in Chelluru, a rural village in India located near Hyderabad. Using computer simulation and optimization, it was compared to a conventional PV-EDR system, a state-of-the-art constant PV-EDR, and a commercial on-grid reverse osmosis (RO) desalination system. “RO uses pressure to force water through a polymer membrane, while its constitutive ions are blocked by the membrane,” the group said.

“The optimized levelized cost of water (LCOW) achieved by the proposed flexible PV-EDR system is US $1.66 m−3, which improves the cost by 22% compared with the current state-of-the-art PV-EDR system and by 46% compared with the conventional PV-EDR system,” the scientists found. “The LCOW for on-grid RO is US $1.71 m−3, 3% above the LCOW of flexible PV-EDR.”

Their findings were presented in “Flexible batch electrodialysis for low-cost solar-powered brackish water desalination,” published in Nature Water. The team included researchers from King’s College London in the UK, and Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (HI ERN) in Germany.

“For the next step, exploring the long-term performance and broadening the application scope of our PV-EDR technology beyond brackish water desalination presents a significant opportunity to address a wider array of global challenges related to water and liquid waste treatment,” concluded He.

From pv magazine global

Scientists from South Korea’s Korea Aerospace Research Institute (KARI) and the Korea Electrotechnology Research Institute presented in a new paper the advancements of their Korean Space Solar Power Satellite (K-SSPS) project. Namely, they presented a conceptual design of the satellite, its end-of-life disposal method, and a first pilot system and experiment.

“The objective of Japan is to develop gigawatt-level space solar power satellites (SSPS) by 2050, and China aims at megawatt-level SSPS by 2035 and gigawatt-level satellites by 2050,” corresponding author, Joon-Min Choi, told pv magazine. “Although Korea entered the field of SBSP relatively late, it has made notable progress. These advancements exemplify Korea’s commitment to achieving Space-Based Solar Power (SBSP) and contribute to the ongoing collective efforts in this field.”

As for the proposed design of the power-transmitting satellite, the group emphasized that it is “not derived from rigorous analyses but rather serves as system requirements for commercial viability.” Per this design, the system will have a mass of 10,000 tons and transmit microwave at a frequency of 5.8 GHz to Earth via a 1.0 km2 antenna. The microwaves can be converted on the ground to usable electricity via rectennas, which are special receiving antennas that are used for converting electromagnetic energy into direct current (DC).

The system is planned to have two solar array wings of 2.2 km × 2.7 km each. It will use 4,000 sub-solar arrays of 10 m × 270 m, made out of thin film roll-out, with a system power efficiency of 13.5%. On the ground, the researchers propose to place 60 rectennas with a diameter of 4 km along the Korean Demilitarized Zone (DMZ). In that case, 60 satellites will have to correspond to the 60 rectennas.

“If each rectenna could generate 2 GW, the total power collected would be 120 GW, providing approximately 1 TWh of electricity per year,” they said. “This amount exceeds South Korea’s electricity consumption in 2021 (0.5334 TWh) and surpasses the combined electricity consumption of South and North Korea for a certain period of time.”

Based on previous literature, with a lifetime of 30 years, such a structure could provide electricity at a price of  $0.03/kWh. Per the proposal, the satellite bus will first get into the low Earth orbit (LEO), where the main structure and the solar arrays will be installed. After conducting some tests, harvested energy will power the K-SSPS journey from the LEO to the geostationary orbit (GEO).

The disposal method proposed is to intentionally collide the structure at the end of its lifetime into the lunar surface, preferably on the rear side of the Moon. This will ensure the complete removal of its debris from space while also potentially recycling valuable materials for future lunar colony residents.

“As we stand on the verge of commercialization, it becomes imperative to scrutinize and illuminate the inherent weaknesses of SBSP and devise effective solutions or mitigation strategies,” the group said. “Of paramount importance is the necessity to articulate a comprehensive disposal methodology for the mega-size structures associated with SBSP. This substantiation is crucial for justifying the development of SBSP.”

According to the researchers, a pilot system aimed at validating power transmission capabilities and verifying the functionality of deployable/expandable devices can be realized in Korea already in the 2020s. The proposed pilot consists of two small 60 × 60 × 80 cm satellites, each with a mass of 120 kg. One of those will act as an electric power transmitter, while the other satellite serves as a receiver.

“The total solar panel area of the power transmission satellite is not sufficient to continuously transfer the power generated by the Sun, despite the solar panels providing a minimum of 0.39 kW of power,” they said. “To overcome this limitation, the power transmission satellite is equipped with two additional batteries, each weighing 4 kg, allowing for the storage of as much solar energy as possible before transmitting the power to the power reception satellite.”

They also explained the input power of the transmitter will be 8.6 kW, while the output power of the transmitter will be 3.44 kW. They calculated the average output power for different distances, ranging from 100 m to 1,000 m. Per their calculation, for 100 meters, the output load is 162 watts, while for 1,000 meters, it can be as low as 0.12 watts.

In 2019, the KARI set a goal of developing a LEO Space Solar Power Test Satellite by 2040 and a GEO SSPS by 2050. Those goals were also adopted in 2022 by the “KARI Technology Strategy.” The current developments were presented in “Case studies on space solar power in Korea,” published on Space Solar Power and Wireless Transmission.

Solar panels are highly recyclable, but the use of thin plastic layers to encase solar cells can cause challenges in recycling valuable materials like silicon or silver effectively.

The National Renewable Energy Laboratory (NREL) has developed a proof of concept that helps cut the use of polymers by making direct glass-to-glass welds in solar cells.

The method makes use of femtosecond lasers, a type of infrared laser that focuses energy on a very short time scale with a single laser pulse. The laser creates hermetically sealed glass-on-glass welds. Femtosecond lasers are currently used in medical eye procedures like cataract surgery today.

The laser welds would eliminate the need for plastic laminates that make recycling more difficult. At the end of their useful life span, the modules made with laser welds can be shattered, and the glass and metal wires therein can be recycled and the silicon reused.

“Most recyclers will confirm that the polymers are the main issue in terms of inhibiting the process of recycling,” said David Young, senior scientist and group manager for the High-Efficiency Crystalline Photovoltaics group in the Chemistry and Nanoscience department at NREL.

NREL published the study in IEEE Journal of Photovoltaics. The authors said the laser is cell material agnostic, able to be used with silicon, perovskites, cadmium telluride, etc., because the heat from the highly focused laser is confined to a few millimeters. The researchers said the welds within the glass are essentially as durable as glass itself.

“As long as the glass doesn’t break, the weld is not going to break,” said Young. “However, not having the polymers between the sheets of glass requires welded modules to be much stiffer. Our paper showed that with proper mounting and a modification to the embossed features of the rolled glass, a welded module can be made stiff enough to pass static load testing.”

A different type of edge sealing using nanosecond lasers and a glass frit filler was tried in the past, but the welds proved too brittle for use in outdoor module designs. The femtosecond laser welds offer superior strength with hermetic sealing at a compelling cost, said NREL.

The research was conducted through the Durable Module Materials Consortium, which targets extending the useful life of solar panels to 50 years or beyond.

From pv magazine Germany

Exactly 70 years ago today, scientists at Bell Labs in New Jersey presented the first practical “solar battery” to the public. The New York Times reported at the time that “this invention could mark the beginning of a new era – the harnessing of the almost limitless solar energy for human civilization.”

However, it took several decades for this vision to become tangible. The global growth of PV has only really gained momentum in the last 10 years. While 1 GW of PV power was installed worldwide throughout 2004, by 2010 it was at 1 GW per month. Five years later, installation reached 1 GW per week and most recently, around 1 GW per day, according to Carsten Pfeiffer, head of strategy at Germany’s Bundesverband Neue Energiewirtschaft association, in a recent Twitter thread. “We will probably see an annual increase of 1 TW within this decade,” he stated.

U.S. scientists Daryl Chapin, Gerald Pearson and Calvin Fuller initially only had the task of developing a reliable energy source for remote telephone systems where conventional batteries had been ineffective. Solar cells made from the semiconductor material selenium had already been developed, but their efficiency was too low for useful applications.

Systematic, months-long development of a silicon solar cell produced the functioning prototype for the first usable solar module, which was presented on April 25, 1954. The efficiency at the time was only 6%. This initially increased slowly in the following decades. Only over the last two decades, due to the industrialization of PV production and accelerated technical progress, has this increased to around 25%, which is close to the physical limit established for silicon solar cells.

Even today, Bell Labs – which was then part of AT&T and now operates under Nokia Bell Labs – calls “the solar cell” one of its “greatest innovations.” The three scientists were posthumously honored for their invention in 2008 by being inducted into the US National Inventors Hall of Fame.

In 2004, the US Department of Energy’s National Renewable Energy Laboratory (NREL) published an article celebrating the cell’s 50th birthday.

Author: Thomas Seltmann

From pv magazine Global

NREL has updated its Best Research-Cell Efficiency Chart. The tool highlights the highest confirmed conversion efficiencies of research cells for a range of PV technologies.

“Everything up to the end of 2023 is included,” a spokesperson from the US Department of Energy’s research institute told pv magazine, noting the chart also includes important results achieved in the first quarter of this year. “The format of the chart will soon change to include hybrid tandems.”

The chart now includes the 33.9% world record efficiency achieved in November by Chinese manufacturer Longi for a perovskite-silicon tandem solar cell and the 27.09% efficiency achieved by the same company for a heterojunction back contact solar cell. Furthermore, it comprises the 23.64% efficiency achieved in March by US-based thin-film module maker First Solar for a solar cell based on copper, indium, gallium and diselenide (CIGS) technology.

With the interactive version of the chart, users can pull up decades of research data and compare custom charts that focus on specific technologies or time periods. They can find data on a cell’s current, voltage output, and fill factor, in addition to efficiency. The availability of those details will depend on the information in NREL’s records.

The highest research cell efficiency recorded in the chart is 47.6%, for a four-junction cell developed by Germany’s Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE).

From pv magazine Global

CSP is experiencing a remarkable resurgence and India unveiled a 50% allocation for CSP in its renewable energy tender for the first quarter of 2024.

Scaling up CSP will bridge the gap caused by intermittent-generation PV and wind projects to help power the world’s most populous country with reliable, affordable, continuous renewable energy.

Rajan Varshney, deputy managing director of the National Thermal Power Corporation, India’s largest state-owned utility company said recently, “Now is the right time for CSP … As PV and wind capacity increases, increasingly more and more coal-based power will be required to make it firm and to supply electricity when the sun is not there. So by increasing PV, we cannot avoid coal unless we install CSP plus storage in Gujarat and Rajasthan.”

CSP’s resurgence may surprise industry insiders who consider the technology obsolete after problems with large scale sites, notably in California and Arizona.

While previous installations were massive, complex, custom-engineered, and not replicable, my company, 247Solar, has obtained finance for a modular version that solves for these challenges.

Our version operates on superheated air at normal atmospheric pressure. It stores energy using simple materials, not molten salt, and it can be mass-produced in 400 kW units for economies of scale.

The model shows promise to greatly shorten project cycles and resume the dramatic CSP cost reductions achieved in its early years and which slowed as the older technology matured.

Demand

Around-the-clock power demand has been rising because of growth in emerging economies and is accelerating due to data centers, cryptocurrency, and artificial intelligence (AI). As we move to electrify with electric vehicles, heat pumps, and industrial heat, CSP emerges as a viable solution to address those needs and provide continuous power.

Grid operators continue to grapple with the variability of photovoltaic and wind energy. Wind, if it blows at night, can help balance daytime solar but wind is much more variable than sunshine and requires long-distance, high-voltage lines to get to market, which can add cost and time to wind farm deployment.

Even large doses of lithium-ion batteries – meant to handle morning and evening peak loads, as gas peaker plants did before them – are nowhere near enough to store the energy it would take to keep the grid powered through the night and during bad weather, as coal plants have. Batteries may also feature conflict minerals, unlike our thermal energy storage systems.

CSP’s levelized cost of energy (LCOE) has fallen dramatically, by almost 70% since 2010, offering longer and more economical energy storage than batteries.

Concentrated solar has returned to projects that will pair it with PV to extend power output into the night, reducing overall LCOE by harnessing synergies between the two technologies.

Pioneers

Some of the high-profile early efforts at CSP got many things right, such as Abengoa Solar’s Solana plant near Phoenix, launched in 2013, or BrightSource’s Ivanpah plant in California, the world’s largest solar thermal site at the time, also in 2013.

Initial CSP plants focused the sun’s heat on a single point, reaching temperatures above 530 degrees Celsius. Our system pushes that limit to around 1,000 degrees Celsius.

Those pioneer sites also stored energy for six- to 12-hour operation at night, aiming for more straightforward, cost-effective technology than polysilicon-based PV modules.

CSP is no longer just huge installations of pipes and mirrors in the desert or towers as high as a wind turbine, however.

We are seeing new interest in 247Solar’s smaller, simpler, more flexible application of this technology.

Our turbines generate electricity from nothing more than superheated air so they don’t require a phase change of the energy from heat to steam as other CSP systems do.

Sustainable

We store the extra heat in cheap, inert materials such as sand, iron slag, or ceramic pellets. This eliminates the need for corrosive, high-maintenance molten salt, along with its other chemical and physical challenges.

Our proprietary thermal batteries provide 18-plus hours of storage for on-demand, industrial-grade heat and electricity. They can produce power during bad weather and, when fully discharged, the generators can even run on green hydrogen, natural gas, or diesel. With a capacity factor of 85%, however, that would occur far less often than in a system of PV plus batteries with a 40% capacity factor.

Our turnkey solution, which we call 247Solar Plants, is modular and factory-built for rapid cost reduction through mass production and easy, quick, on-site assembly.

Each module has 400 kW of generation capacity with 120-foot towers – half the height of earlier versions of CSP. With fewer moving parts than conventional CSP, our solar thermal power plant is also easier to maintain in a hostile environment.

We hold more than 30 patents worldwide, including a blanket patent just obtained in India, for our entire CSP system; as well as our proprietary solar collectors; ultra-efficient Heat2Power turbines, that use ambient air pressure; and inexpensive thermal battery systems.

Hybrid

This hybrid approach leverages the strengths of CSP and photovoltaics to generate uninterrupted power 24/7, with PV providing cheap electricity during the day while CSP stores its excess energy as heat for use at night.

Other companies, such as Heliogen, BrightSource Energy, and Acciona, are also pushing the boundaries of CSP with advancements in AI-enabled systems, alternatives to the shortcomings of molten salt storage, and lower-cost parabolic trough technology.

Potential applications for CSP include on- or off-grid combined heat and power, microgrids, ultra-heat for heavy industry, green hydrogen, and green desalination, as well as baseload power 24/7/365 – critical in fast-growing economies such as India’s.

“Emerging technologies such as solar thermal and concentrated solar power are essential for India to meet its renewable energy targets,” said India’s New & Renewable Energy Secretary Bhupinder Singh Bhalla, at the opening of the International Conference on Solar Thermal Technologies in New Delhi, in February 2024.

CSP is unmatched, especially when integrated with photovoltaics, for 24/7 dispatchability of flexible, dependable, and resilient zero-carbon power to meet the energy demands of tomorrow.

Bruce Anderson is a visionary in the solar industry for four decades, is founder and chief executive officer of 247Solar, which is commercializing a concentrating solar technology invented at MIT and which runs on superheated compressed air instead of steam. His career spans seven company ventures, a “New York Times” bestseller, and the American Solar Energy Society’s Lifetime Solar Contribution Award.