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TERRENUS ENERGY

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Glass pyramid concentrator for solar cell applications

Image: Stanford University, Nina Vaidya

Stanford University scientists have built an optical concentrator that purportedly harvests more than 90% of the light that hits its surface.

From pv magazine

Researchers at Stanford University have created a glass pyramid optical concentrator that concentrates light on solar cells, regardless of the light incidence angle.

“It’s a completely passive system – it doesn’t need energy to track the source or have any moving parts,” said research coordinator Nina Vaidya. “Without optical focus that moves positions or need for tracking systems, concentrating light becomes much simpler.”

The AGILE (Axially Graded Index LEns) device purportedly harvests more than 90% of the light that hits its surface. It also creates spots at the output that are three times brighter than the incoming light.

“Installed in a layer on top of solar cells, they could make solar arrays more efficient and capture not only direct sunlight, but also diffuse light that has been scattered by the Earth’s atmosphere, weather, and seasons,” the scientists explained, noting that the solar cell could be built with fewer raw materials and at lower costs.

They said a top layer of the concentrator could be used to replace existing encapsulation materials. That would in turn create space for cooling and circuitry to run between the narrowing pyramids of the individual devices. The pyramid was made of different optical glass flats provided by Japan’s Ohara Corp.

“The geometry of the pyramid was a square of side 14.5 mm down to a square of 8.5 mm giving a concentration of three, along a total height of 8 mm with 8 glass layers, with each flat 1 mm thick,” the academics said.

They layered the glass together with polymers that bend light to different degrees. “The layers change the light’s direction in steps instead of a smooth curve,” they said. “The sides of the prototypes are mirrored, so any light going in the wrong direction is bounced back towards the output.”

The prototype can improve optical concentration by a factor of three and achieve a 90% efficiency in capturing light, they claimed in “Immersion graded index optics: theory, design, and prototypes, which was recently published in Microsystems and Nanoengineering.

“Results of the functional prototypes demonstrate that immersion graded index technology can improve the way we concentrate and couple light many fold,” the scientists said. “The AGILE has the potential to greatly improve opto-electronic systems by reducing cost, increasing efficiency, providing a scalable concentration system with built-in anti-reflection and encapsulation without the need for tracking.”

Author: Emiliano Bellini

Photon-enhanched rechargeable batteries for solar storage

Image: Image: National Institute for Materials Science (NIMS), Nano Research Energy, Tsinghua University Press

Japanese scientists have analyzed storage systems that combine PV and high-energy-density metal batteries. The rechargeable batteries have advantages such as low-charge voltage and high energy density, but stability and safety must be addressed before they reach commercial maturity.

From pv magazine

Researchers from the National Institute for Materials Science (NIMS) in Japan have reviewed different photo-enhanced rechargeable metal batteries featuring PV and high-energy-density metal batteries for direct solar-to-electrochemical energy storage.

They looked at devices integrating PV and lithium-ion, zinc-ion, lithium-sulfur, lithium-iodine, zinc-iodine, lithium-oxygen, zinc-oxygen, and lithium-carbon dioxide storage systems.

“Despite the respective significant progress in rechargeable batteries and photovoltaic techniques in the past decades, integrating different rechargeable batteries with solar energy in an effective and low-cost way remains a great challenge,” they said.

They divided the battery technologies into two categories: closed-type photo-enhanced rechargeable metal batteries and open-type photo-enhanced rechargeable metal batteries. They analyzed the advantages and disadvantages of each kind of battery.

As a general rule, photon-enhanced batteries with PV can provide better performance for low charge voltage and high energy density, which makes them suitable for smart electronics and optoelectronics. However, stability and safety should be improved to help such devices to reach commercial viability.

“For example, rechargeable lithium-ion batteries, which we are all familiar with because they are used in many modern electronic devices, including laptops, phones, and electric vehicles, are efficient, but would be difficult to scale for solar energy use because of their complicated structure,” they said.

The scientists noted the importance of standardizing experimental conditions and developing effective thermal management systems for stable operation.

“Standard experimental conditions conducive to the comparison of overall performance in different systems need to be established. For photo-enhanced rechargeable batteries, light illumination is indispensable,” they explained.

Thy introduced the battery technology in “Photo-enhanced rechargeable high-energy-density metal batteries for solar energy conversion and storage,” which was recently published in Nano Energy.

“It is necessary to explore more suitable electrode materials and optimize the device structure of the batteries,” said researcher Hairong Xue. “By addressing some critical challenges involving working mechanism, electrode materials, and battery structure design, the goal is to demonstrate viable uses of photo-enhanced rechargeable batteries in electronic and optoelectronic devices.”

Author: Emiliano Bellini

CEA-INES develops 18.95%-efficient flexible perovskite solar panels

Image: CEA-INES

French researchers have developed PV modules with an area of 11.6 square centimeters for indoor applications. They said the achieved efficiency level marks a world record for a flexible perovskite device larger than 10 square centimeters.

From pv magazine France

Researchers at France’s National Solar Energy Institute (INES) – a division of the French Alternative Energies and Atomic Energy Commission (CEA) – have developed new flexible perovskite solar modules.

They have a surface area of 11.6 square centimeters, with a maximum power conversion efficiency of 18.95% and a stabilized efficiency of more than 18.5%. INES said the performance is a world record for a flexible perovskite device larger than 10 square centimeters.

Currently, the power conversion efficiencies of solar devices based on perovskites indeed exceed 25% for single junctions and 29% in tandem structures with silicon. However, these results are obtained on small surfaces, of the order of 1 square centimeters.

To obtain this yield on larger surfaces, INES developed the flexible perovskite solar modules at low temperature on low-cost substrates made of polyethylene terephthalate (PET). They used a very simple structure featuring five layers, including the electrodes.

The performance is obtained after encapsulation and the stability of the devices has been tested under damp heat conditions at 85 C, according to the standards used for silicon-based technologies. A stability of several hundred hours has been obtained – between 400 and 800 hours, depending on encapsulation – based on a standard objective of 1,000 hours.

To achieve this result, the CEA optimized the stacking of the layers of the cell to implement a three-step laser process for the production of the module. It also developed a flexible encapsulation process that is fully compatible with high gas barrier materials, with no initial loss.

The CEA’s devices will be integrated into a demonstrator for building-integrated photovoltaic (BIPV) applications by Flexbrick (Es), a member of the European consortium. The modules will be interconnected to obtain high voltages and will be tested according to building standards. In addition, stability tests in real conditions are currently being carried out.

The Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE) in Germany, a project partner, is testing the panels for indoor applications. The tests have already shown power conversion efficiencies of up to 24.5% at very low light (500 lux).

For some applications, the use of flexible substrates could be of interest for single-junction perovskite technology, because it could open the way to high-speed and low-temperature printing processes. It therefore becomes possible to use low-cost substrates unlike flexible inorganic technologies, such as CIGS, which require higher temperature processes and more expensive substrates.

Many teams around the world are trying to meet the challenges of making larger devices with sufficient stability for real-world applications. This is one of the tasks set by the partners of the European APOLO project.

Author: Gwénaëlle Deboutte

Agrivoltaics for broccoli, cabbage

Image: Chonnam National University

Scientists in South Korea have combined PV generation with vegetable farming and have found that solar array shading provides favorable results for crops such as broccoli and cabbage.

From pv magazine

A research team at Chonnam National University in South Korea has looked at how solar power generation could be combined with broccoli and cabbage cultivation. The team found that the shading provided by a PV facility could improve the quality of crops.

Broccoli and cabbage need to be grown in places that receive full sun, which means between six and eight hours of sunlight per day, or very light shade. A lack of sunlight could result in thin, leggy plants.

“Because of its low light saturation points, broccoli may be a suitable crop to maximize famer’s profits and energy security through an agrivoltaic system,” the scientists said. “However, to date, there is limited information on the performance of brassica crops in agrivoltaics.”

The scientists built their agrivoltaic system with bifacial modules at a height of 3.3 meters. They achieved an average power generation per day of 127 kWh during the testing period. They claimed that their approach demonstrated the technical and economic viability of the proposed agrivoltaic solution.

“We found that the taste and the quality of the broccoli were not lower than those of a reference field without the solar array,” they said. “We also found no significant change in functional ingredients and metabolites that affect taste.”

The PV installation caused a significant reduction in the light hitting the crops, which in turn resulted in an improvement of their color.

“The color of broccoli is an important property that goes beyond appearance quality and is involved in consumers’ desire to purchase,” the scientists said.

They said that presence of the PV system reduced the agricultural yield by around 20%, compared to the reference field without solar. However, they said that the income generated by the solar array could more than compensate for such losses.

“The annual economic benefit from solar power was 10.4 times more than the broccoli production benefits,” the scientists said. “Therefore, farmer benefits will increase as they are cultivated in agrivoltaics compared to open field.”

The researchers presented their findings in “Agrivoltaic Systems Enhance Farmers’ Profits through Broccoli Visual Quality and Electricity Production,” which was recently published in Agronomy.

“In terms of land use efficiency, agrivoltaic is a good means of producing energy and food in Korea, which is a highly mountainous area,” they said.

Author: Emiliano Bellini

RETC releases 2022 Module Index Report

Image: RETC

The Renewable Energy Test Center has released a new report on PV module performance.

From pv magazine USA

The Renewable Energy Test Center (RETC) has released its “2022 PV Module Index” (PVMI) report, highlighting module performance across a variety of lab tests, while also providing industry-cited clarifications on the real-world significance of the results.

The 2022 PVMI marks the first edition released since VDE acquired a 70% stake in RECT. President and CEO Cherif Kedir said the move will allow RETC to expand its testing services to a broader network of manufacturers, investors, insurers and developers, all in pursuit of minimizing risk and uncertainty in favor of long-term reliability, sustainability and profitability by designing better data-driven risk mitigation programs and service products.

RETC Vice President of Business Development Daniel Chang told pv magazine the 2022 PVMI takes a more forward-looking approach than previous editions, supplementing testing results and hardware performance with emerging industry trends that are going to guide the use of this hardware and investments in projects that utilize it into 2023 and beyond.

Cherif Kedir, President and CEO of RETC

“We focus on what we think are going to be topics that are going to be relevant for the upcoming year, like the onset of N-Type modules, and field services,” explained Chang. “There are a lot of installations out there degrading at a faster pace than expected. These installations are investments in assets made by banks to yield some sort of financial benefit to them, right? If they have some sort of degradation, then that’s not performing the way that was expected and planned for.”

Specifically, RETC is interested in forensic analysis of PV systems to determine the root causes of underperformance. This investigation is the culmination of different analyses to be done over the life of a project, starting with a baseline third-party module health assessment during project commissioning.

In instances of underperformance, RETC recommends Electroluminescence (EL) testing. EL testing uses a special camera system to document the light emissions that occur when an electrical current passes through PV cells. The technology has long been used in labs to detect a wide range of hidden module defects.

Another aspect of forensic analysis is predictive maintenance, wherein a third party inspects plants from periodically to detect issues that may not be visible at a base overview, but could develop into much larger issues if allowed to linger.

While Chang brought to light the ongoing issue of degradation and the developing need for advanced field services, Kedir focused more on the technology side, researching where the next wave of module innovation will come in a post-large-format world.

Panasonic Heterojunction with Intrinsic Thin Layer (HIT) solar cell

That innovation, he thinks, will come from heterojunction n-type modules (HJT).

“I think leading manufacturers are kind of a crossroad point right now, in terms of how to get more power out of modules without making the modules just unreasonably large, because they’re already pretty damn big,” Kedir said. “The other reason I think manufacturers may be hesitant to make their modules larger is that everybody is testing the waters with heterojunction cells, so that they can eke out more more watts per module, without having to increase the size. With the module technologies they currently have, I don’t think they’re able to get a lot more efficiency out of the cell, so they’re trying to figure out how to get more power without increasing the module size, and the next, the next logical thing is to go to different technologies, Topcon and heterojunction.”

In an op-ed for pv magazine in November 2021, Nadeem Haque – chief technology officer at Heliene – outlined some of the distinct technology advantages that HJT presents. HJT cell manufacturing involves the deposition of an amorphous layer of silicon on both the top and bottom of the wafer followed by a transparent conducting oxide deposition and making of metal contacts.

HJT cell production lines are currently expensive, almost prohibitively so, and new lines need to be built. The cells require a more expensive metallization paste to manufacture. HJT cells are by nature bifacial, with bifaciality rates above 90%, the highest of any cell technology. Higher bifaciality and lower temperature coefficients result in higher energy output, and HJT cells in mass production are expected to reach about 27% efficiency.

“You can gauge where the industry is going based on where investment money is going, and we hear a lot about companies investing money in heterojunction cell lines in Asia, so I think that’s probably going to be a trend,” said Kedir.

The last industry trend examined by RETC is mitigating the effects of extreme weather on PV systems, a topic which pv magazine has reported on extensively with RETC and other partners, like VDE Americas.

Module index

The core of the report is a review of modules’ performance across a range of tests that are designed to go beyond the parameters of tests for certification and accurately project what each module’s strengths are, rather than compare and rank them against one another.

The tests are split up into three categories, each of which analyzes a different aspect of module excellence: quality indicators, performance indicators, and reliability indicators. In testing, the researchers at RETC noticed a new trend that some of the performance and reliability gaps from manufacturer to manufacturer have widened, as opposed to the narrowing they observed in recent years.

“Some of the issues that we saw over the last year have been related to manufacturers faced with their own supply chain issues and inability to get their raw materials,” explained Kedir. “They’ve had to go to other sources, secondary and tertiary sources of cells and backsheets, and then that triggered a few failures, we saw more of them last year. What’s been lingering is potential-induced degradation (PID) and some related performance stuff. On cells, PID, for all intents and purposes, had been completely solved a few years ago, but then it reappeared throughout the pandemic, with the supply chain issues, we see some of that leftover.”

This is a phenomenon that Kedir expects to see continue, at least in the short term. The issue may linger as a result of the recently-announced two year moratorium on the DOC’s anticircumvention case, he said.

“Demand is going to is going to pick up in the US,” he began. “The upcoming traceability requirements are going to put a constraint on the cell supply from forced labor regions, which means you’re not going to have enough cell supply for them for the market demands. This causes supply separation between manufacturers. Some larger manufacturers have already completely mitigated that issue, developed a new supply chain for polycrystal, and have new cell lines in Southeast Asia. Those guys are going to fare out much better than a manufacturer who hasn’t put in that infrastructure already. They’re going to have to try to source cells from other places or other manufacturers that may or may not be as good as their initial supply.”

While the gap between top-tier, established module manufacturers and some newer market entrants is widening, RETC still had a number of manufacturers perform well across their litany of tests.

Based on available testing data, RETC highlighted Hanwha Q CELLS, JA Solar, and LONGi Solar as the overall top three performers of the year. The recognition does not stop with the top performers, however, and RETC listed some of the manufacturers who scored the highest marks in individual tests, listed below.

Hail durability:

  • LONGi Solar

Thresher test:

  • Hanwha Q CELLS
  • JA Solar
  • LONGi Solar
  • Tesla

LeTID resistance:

  • Hanwha Q CELLS
  • Jinko Solar
  • LONGi Solar
  • Trina Solar

LID resistance:

  • Hanwha Q CELLS
  • JA Solar
  • Jinko Solar
  • LONGi Solar
  • Trina Solar

Module efficiency:

  • JA Solar
  • LONGi Solar
  • REC Solar
  • Silfab Solar
  • Tesla
  • Yingli Solar

Pan file performance:

  • JA Solar
  • Jinko Solar
  • LONGi Solar
  • Trina Solar

PTC-to-STC ratio

  • Hanwha Q CELLS
  • JA Solar
  • REC Solar
  • Silfab Solar
  • Tesla
  • Yingli Solar

Damp heat test

  • JA Solar
  • LONGi Solar
  • Hanwha Q CELLS
  • Tesla

Dynamic mechanical load test:

  • JA Solar
  • Jinko Solar
  • LONGi Solar

PID resistance:

  • JA Solar
  • Jinko Solar
  • LONGi Solar

Thermal cycle test:

  • Hanwha Q CELLS
  • JA Solar
  • Jinko Solar
  • LONGi Solar
  • Tesla

RETC said the rankings are comprehensive only to data that the company has collected, so modules from other manufacturers could perform similarly to the ones listed above, but the organization cannot make an overall determination regarding high achievement in manufacturing without module tests data across the three categories.

The report concludes with a look at a number of notable changes and revisions anticipated in the upcoming edition of IEC 61730, a two-part standard pertaining to PV module safety qualification, as well as upcoming updates to IEC TS 62915, a technical specification pertaining to PV module approval, design and safety qualification.

The standards analysis is expansive, and pv magazine will cover these pending changes in a follow-up to this article.

Author: Tim Sylvia

New on-demand rooftop solar investment platform

Image: Eneco Group, Flickr

Legends Rooftop is an online tool that allows investors to purchase off-site rooftop solar panels as a financial investment.

From pv magazine USA

Startup Legends Solar has unveiled a new early-access product, Legends Rooftop, which is an online, on-demand solar investment platform. The platform allows people to purchase anywhere from one solar panel to an entire array on a remote commercial rooftop. It is pitched as a way for millennial investors to access the benefits of solar.

Users select how many panels they want to invest in, with the smallest investment starting at a few hundred dollars. The platform tracks the performance of the panels and banks the energy savings created by the solar project in the user’s account. Withdrawals can be made at any time, said Legends Solar.

The company said there are some risks in the investment, including poor weather conditions, failure of payment by the “offtaker” or power purchaser, unexpected maintenance, or natural disasters and physical damage. It said that hospitals and universities are usually very consistent offtakers.

“With Legends Solar, you can invest in a single remotely located panel, or a whole rooftop’s worth, even without the suburban minimansion and white picket fence,” said Legends Solar CEO Lassor Feasley.

SDC Energy will serve as a financial partner for Legends Solar. The company has performed hundreds of solar financings in the past.

“The team at Legends Solar has challenged us to reimagine our approach to raising equity for new solar facilities,” said SDC Energy President Charles Schaffer. “We look forward to unlocking the solar asset class for a wider and more diverse set of retail investors. By doing this, we will accelerate the transition to a carbon free society and spread its financial benefits more equitably.”

The tool tracks solar production, the amount of carbon abated, total cash earned, and dividend payments.

Author: Emiliano Bellini

Solar window generates electricity, thermal energy

Image: Hong Kong University of Science and Technology, Advanced Science, Creative Commons License CC BY 4.0

A research team in Hong Kong has built a solar window that can generate power on the external side via a luminescent solar concentrator and thermal energy on the internal side via transparent solar absorbers.

From pv magazine

Scientists from the Hong Kong University of Science and Technology have developed a dual-band selective solar harvesting (SSH) window based on transparent photovoltaics (TPVs) and transparent solar absorbers (TSAs). The TSAs are used to convert ultraviolet (UV) or near-infrared (NIR) light by converting it into thermal energy.

“The harvested thermal energy is extracted by ventilated air to provide indoor space heating in cold seasons or abate indoor cooling loading in hot seasons,” they explained. “We demonstrated that the SSH window has a visible transmittance of 42%, achieves a solar-electricity conversion efficiency of 0.75%, and a solar-thermal conversion efficiency of 24% with a ventilated air temperature rise of 10 C.”

The research group used a luminescent solar concentrator (TPV) based on copper indium sulfide and zinc sulfide (CuInS2/ZnS) quantum dots (QDs) as the exterior window. It is able to collect UV light and convey it to opaque PV devices that are located at the edge of the transparent substrate for electricity generation. The TSAs were instead used to fabricate the interior side of the window where heat is produced and collected.

“The thermal energy is mostly extracted by the ventilated air within the gap for various purposes such as indoor space heating in cold seasons,” the group said.

The academics fabricated a prototype measuring 30 cm x 30 cm x 2.4 cm by assembling the TPV elements with the TSAs on the interior side. They claim the device showed a substantial visible transmittance and that it was able to generate 6 W per square meter of power and the thermal power of around 150 W per square meter.

“Thermal power is 25 times of the generated electrical power, suggesting that the harvesting thermal power is of primary importance for building-integrated solar energy harvesting windows,” they said. “With thermal energy harvesting by air ventilation, the total effective efficiency was estimated over 30% at a typical operating condition for building space heating applications.”

They presented their findings in “Selective Solar Harvesting Windows for Full-Spectrum Utilization,” which was recently published in Advanced Science.

“The SSH window can save the annual heating, ventilation, and air conditioning (HVAC) energy consumption by up to 61.5% compared with the normal glass, in addition to the generated electricity that accounts for up to 19.1% of the annual energy saving amount,” they said.

Author: Emiliano Bellini

Solar panels based on biosourced materials

A recycled glass panel on the front and a linen composite on the back. Image: GD

French solar energy institute INES has developed new PV modules with thermoplastics and natural fibers sourced in Europe, such as flax and basalt. The scientists aim to reduce the environmental footprint and weight of solar panels, while improving recycling.

From pv magazine France

Researchers at France’s National Solar Energy Institute (INES) – a division of the French Alternative Energies and Atomic Energy Commission (CEA) – are developing solar modules featuring new bio-based materials in the front and rear sides.

“As the carbon footprint and the life cycle analysis have now become essential criteria in the choice of photovoltaic panels, the sourcing of materials will become a crucial element in Europe in the next few years,” said Anis Fouini, the director of CEA-INES, in an interview with pv magazine France.

Aude Derrier, the research project’s coordinator, said her colleagues have looked at the various materials that already exist, to find one that could allow module manufacturers to produce panels that improve performance, durability, and cost, while lowering the environmental impact. The first demonstrator consists of heterojunction (HTJ) solar cells integrated into an all-composite material.

“The front side is made of a fiberglass-filled polymer, which provides transparency,” Derrier said. “The rear side is made of composite based on thermoplastics in which a weaving of two fibers, flax and basalt, has been integrated, which will provide mechanical strength, but also better resistance to humidity.”

The flax is sourced from northern France, where the entire industrial ecosystem is already present. The basalt is sourced elsewhere in Europe and is woven by an industrial partner of INES. This reduced the carbon footprint by 75 grams of CO2 per watt, compared to a reference module of the same power. The weight was also optimized and is less than 5 kilograms per square meter.

“This module is aimed at the rooftop PV and building integration,” said Derrier. “The advantage is that it is naturally black in color, without the need for a backsheet. In terms of recycling, thanks to thermoplastics, which can be remelted, the separation of the layers is also technically simpler.”

The module can be made without adapting current processes. Derrier said the idea is to transfer the technology to manufacturers, without additional investment.

“The only imperative is to have freezers to store the material and not to start the resin cross-linking process, but most manufacturers today use prepreg and are already equipped for this,” she said.

The INES scientists also looked into the solar glass supply issues encountered by all photovoltaic players and worked on the reuse of tempered glass.

“We worked on the second life of glass and developed a module made up of reused 2.8 mm glass that comes from an old module,” said Derrier. “We have also used a thermoplastic encapsulant which does not require cross-linking, which will therefore be easy to recycle, and a thermoplastic composite with flax fiber for resistance.”

The basalt-free rear face of the module has a natural linen color, which could be aesthetically interesting for architects in terms of facade integration, for example. In addition, the INES calculation tool showed a 10% reduction in the carbon footprint.

“It is now imperative to question the photovoltaic supply chains,” said Jouini. “With the help of the Rhône-Alpes region within the framework of the International Development Plan, we therefore went looking for players outside the solar sector to find new thermoplastics and new fibers. We also thought about the current lamination process, which is very energy intensive.”

Between the pressurization, the pressing and the cooling phase, the lamination usually lasts between 30 and 35 minutes, with an operating temperature of around 150 C to 160 C.

“But for modules that increasingly incorporate eco-designed materials, it is necessary to transform thermoplastics at around 200 C to 250 C, knowing that HTJ technology is sensitive to heat and must not exceed 200 C,” said Derrier.

The research institute is teaming up with France-based induction thermocompression specialist Roctool, to reduce cycle times and make shapes according to the needs of customers. Together, they have developed a module with a rear face made of polypropylene-type thermoplastic composite, to which recycled carbon fibers have been integrated. The front side is made of thermoplastics and fiberglass.

“Roctool’s induction thermocompression process makes it possible to heat the two front and rear plates quickly, without having to reach 200 C at the core of the HTJ cells,” Derrier said.

The company claims the investment is lower and the process could achieve a cycle time of just a few minutes, while using less energy. The technology is aimed at composite manufacturers, to give them the possibility of producing parts of different shapes and sizes, while integrating lighter and more durable materials.

Authors: Gwénaëlle Deboutte and Marie Beyer

A fast-changing renewables PPA landscape

Structured PPAs are becoming more common in mature PV markets, where risks are shared. Image: Axpo Solutions

Power purchase agreements are ideal risk-management tools, given that electricity price volatility is the new normal and renewables uptake is a matter of urgency due to untenable Russian gas dependency. pv magazine sat down with Andy Sommer, team leader of fundamental analysis and modeling at Swiss trader Axpo Solutions, to discuss the situation of prices and PPAs in Europe.

From pv magazine 05/2022

Wholesale electricity prices in Europe have been rising – a trend which started before the war in Ukraine, but is no doubt exacerbated by it. How long will it continue?

It’s impossible to tell of course, nobody has a crystal ball and under current conditions predicting in the near term, let alone the more distant future, is risky. It’s a basic liability issue. But we can understand the many different factors, including how long Russia’s war against Ukraine lasts, and whether imports of Russian gas by Europe (and potentially other relevant countries, especially in Asia) will eventually be banned. The weather in Asia and the Americas, and the availability of replacements for Russian coal in Europe/Japan are other factors which could contribute to continued price increases.

The medium-term development is important for those planning and building PV power plants. What do you expect for wholesale electricity prices in the medium term (five to 10 years)? Can PV investors rely on higher revenues?

As mentioned, the short-term outlook for Europe’s electricity prices is almost impossible to judge right now. Neither can we predict with any certainty whether politicians are going to intervene further in the markets, affecting how fast renewable power generation capacities can expand, for example.

Assuming that PV and wind will continue to be built quickly (supported either by subsidies or favorable market conditions), that the phasing down of coal and nuclear continues as scheduled, and the general energy transition progresses, we believe wholesale market prices will decline substantially in the mid-term versus current levels. This would be due to the presence of more renewable energy sources (RES) in the system, reducing the need for low-efficiency thermal plants, and a significantly less tight gas market (with increasing volumes of LNG coming online around 2025) more than compensating for higher carbon costs.

In the long term, factors such as the cost of investment in carbon capture, utilisation and storage and green hydrogen technologies could become a stabilising influence. Nevertheless, as long as Europe is dependent on LNG imports to cover its gas needs, the market will remain dependent on weather, as well as economic and political conditions in Asia and other regions of the world.

Axpo is a major PPA offtaker in Europe. What does electricity price volatility mean for new solar PPA prices and contracts?

The risks associated with PV development through PPAs have not changed; they always existed. However, we are now seeing most of them under an unprecedented spotlight, including factors such as electricity price volatility, regulatory uncertainty, CPI shocks, transportation difficulties, and permitting delays, among others.

PPAs as risk mitigation tools are adapting to this new reality with more flexible approaches to cope with potential delays, more short-term contracts to capture temporary price spikes, floor structures to leave potential price upsides within the project developer, and more structured approaches to capture higher prices, such as baseload hedges instead of traditional pay-as-produced contracts, and more.

PV plants with a PPA business model don’t need subsidies. Considering that electricity prices are high, what limits the growth of this sector?

Current limits include the not-in-my-backyard or the NIMBY social phenomenon, the limitations of electricity grid infrastructure, and sometimes complex, lengthy and bureaucratic approval/permitting processes, although these hurdles are now beginning to be addressed politically.

The PV-PPA market in Spain is probably the most mature in Europe. What can other countries learn from there?

We have seen the Iberian PV-PPA market evolve over a very short period of time. We started with traditional pay-as-produced structures, in which the producer is paid a fixed price for the full production of a power plant. It was an environment where there was little demand for buying power long-term, and PPAs were seen as an alternative to pay-as-produced feed-in-tariffs.

In a more mature market with many different players, we now see more structured PPAs, where risks are not only borne by the off-taker, but also shared between the two parties. It makes a lot of sense, since pay-as-produced contracts provide very limited returns on the investment and are only suitable for very risk-averse investors. Higher ROIs are still achievable in more sophisticated PPA structures with shared risks, which should be suitable for investors with greater market knowledge and experience.

Does the uncertainty of electricity price instability make PPAs more attractive?

It most certainly does. PPAs are risk management tools that enable developers to secure their investments. These contracts are adapting to different investor needs and market views.

Solar cell efficiencies at a glance – updated

A heterojunction solar cell made by the University of New South Wales. Image: University of New South Wales

A research group led by Professor Martin Green has published Version 60 of the Solar cell efficiency tables.

From pv magazine

An international research group led by Professor Martin Green from the University of New South Wales in Australia has published Version 60 of “Solar cell efficiency tables” in Progress in Photovoltaics.

The scientists said they have added 15  new results to the new version of the tables since January. They also noted that an appendix describes new approaches and terminology.

Since 1993, when the tables were first published, the research group has seen major improvements in all cell categories.

“Copper, indium, gallium and selenium (CIGS) and multijunction cells have seen the most consistent gains, although perovskites have recently seen similar overall gains compressed into a shorter timescale,” Green told pv magazine in an interview last year.

He said that the most important factor for inclusion in the tables is that all results should be independently measured at test centers on the group’s list.

“All of our recognized test centers are carefully vetted prior to inclusion on our list and have been involved in round-robin testing with one another, ensuring consistency of measurements to well within the uncertainty estimates included with the published results,” said Green.

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

Author: Emiliano Bellini