Solar Energy

Linking two solar technologies is a win-win for efficiency and stability

Published

7 months ago

November 16, 2023

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Linking two solar technologies is a win-win for efficiency and stability

by Staff Writers

Princeton NJ (SPX) Oct 16, 2023

While conventional silicon-based solar cells have had an unmistakable impact on the buildout of renewable energy resources around the world, additional performance improvements have become increasingly difficult to make as the devices approach their practical efficiency limits. This constraint has prompted scientists to seek out new technologies that can be combined with silicon cells to unlock higher efficiencies.

Solar cells made with crystals called perovskites are one such technology that have rapidly emerged as an appealing low-cost add-on, but perovskite cells are notoriously susceptible to voltage-induced changes – the shade cast from an overhanging tree branch or nearby plant can zap an entire module within minutes.

Now, researchers from Princeton University and the King Abdullah University of Science and Technology (KAUST) have connected the well-established silicon solar cell with the up-and-coming perovskite in a tandem solar cell to not only boost overall efficiency, but also to strengthen stability. The results, reported in Joule on Sep. 5, illustrate that the connection protects the frail perovskite solar cell from voltage-induced breakdown while attaining greater efficiencies than either cell can achieve on their own.

“Tandem solar cells have already demonstrated power conversion efficiencies that are greater than either silicon or perovskite solar cells alone,” said Barry Rand, research leader and professor of electrical and computer engineering and the Andlinger Center for Energy and the Environment. “We thought that in addition to their higher efficiencies, tandem solar cells could also solve some of the stability challenges facing perovskites by linking them with silicon cells, which are much more stable.”

To test their hypothesis, the researchers built three strings of solar cells: one containing only silicon solar cells, one with only perovskites, and one composed of tandem solar cells, with the two technologies connected in a series. The researchers then shaded one of the cells in the string to simulate the partial shading conditions that a solar array may encounter at least once in its decades-long lifespan.

Such partial shading usually spells doom for perovskites, as the still-illuminated cells force charge to flow through the now-shaded and inactive cell, quickly degrading both it and the entire module. Silicon solar cells, on the other hand, are much more resilient to voltage fluxes, and can endure periods of partial shading with fewer issues.

As expected, the perovskite-only solar module quickly deteriorated after partial shading, while the silicon solar module was only minimally impacted. Interestingly, however, the tandem solar module was just as resilient as the silicon-only module, implying that by connecting the two solar technologies, the silicon cell was able to mask the frailty of the perovskite.

“When you combine two different materials to form a final product, usually it’s the weakest link that ends up determining the overall strength of the chain,” said co-author Stefaan De Wolf, professor of material science and engineering at KAUST. “But in this case, it’s actually the stronger component that protected the weaker one.”

The researchers said their findings demonstrate that partial shading – which has been a major obstacle to perovskite-only modules – may be a negligible concern for series-connected tandem solar devices.

The team also said that the findings bode well for the commercialization prospects of perovskites, because they imply that perovskites may have the most potential when deployed in complement with silicon solar cells, for which a mature manufacturing ecosystem already exists. Instead of having to build a competing manufacturing process, perovskites could be added onto the commercially proven production process for silicon solar cells.

While the team noted that several challenges in addition to partial shading remain to be solved before tandem solar cells achieve the lifespan expected of commercial solar technologies, such as their poor resilience to heat, they said that tandem devices could enable solar research to continue evolving after silicon solar cells hit their upper power conversion efficiency limits.

“If some other stability challenges can be solved, tandem solar cells could essentially take an already successful commercial technology and make it even better,” Rand said. “Our results make a strong case that tandem devices should be an all-hands-on-deck area for future solar research.”

Research Report:Reverse-bias resilience of monolithic perovskite/silicon tandem solar cells

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Solar Energy

Solar investment outstrips all other power forms: IEA

Published

2 days ago

June 6, 2024

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Solar investment outstrips all other power forms: IEA

by AFP Staff Writers

Paris (AFP) June 6, 2024

More money is pouring into solar power than all other electricity sources combined, with investments set to reach half a trillion dollars this year, the world’s top energy research body said Thursday.

The International Energy Agency (IEA) forecast in a report that global investment in clean energy this year will hit $2 trillion, twice the amount going to fossil fuels.

It said combined investment in renewable power and grids overtook the amount spent on fossil fuels for the first time in 2023.

“Clean energy investment is setting new records even in challenging economic conditions, highlighting the momentum behind the new global energy economy,” IEA executive director Fatih Birol said in a statement accompanying the agency’s annual World Energy Investment report.

Companies and governments worldwide are raising spending on clean energy production to reduce the carbon emissions from burning fossil fuels that are driving deadly climate change.

The report said improving supply chains and lower costs were driving up investment in forms of so-called clean energy, which include solar panels, wind turbines, electric cars and heat pumps, as well as nuclear power generation.

Combined investment in renewables and nuclear for electricity generation is now set to reach 10 times the amount going to fossil-fuel power, led by solar, with China investing the biggest share.

“More money is now going into solar PV (photovoltaic panels) than all other electricity generation technologies combined,” the report said.

Solar panel costs have decreased by 30 percent over the past two years and in 2024 “investment in solar PV is set to grow to $500 billion as falling module prices spur new investments.”

By comparison, global upstream oil and gas investment is expected to increase by seven percent in 2024 to reach $570 billion, following a similar rise in 2023.

The IEA warned however of “major imbalances and shortfalls in energy investment flows in many parts of the world” where clean energy projects remain prohibitively expensive.

Excluding renewable energy giant China, the $300 billion invested by emerging and developing economies remained “far below what is required to meet growing energy demand in many of these countries”.

“More must be done to ensure that investment reaches the places where it is needed most,” Birol said.

The IEA said that meeting medium-term global goals to reduce harmful carbon emissions would require investment in renewable power to be doubled worldwide by 2030.

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Solar Energy

Atlas reveals solar energy potential in Germany

Published

2 days ago

June 6, 2024

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Atlas reveals solar energy potential in Germany

by Robert Schreiber

Berlin, Germany (SPX) Jun 06, 2024

Which roofs are suitable for solar panel installations? Where are photovoltaic systems already in place? How much output could be achieved with solar panel arrays at specific locations? A map developed by the German Aerospace Center (Deutsches Zentrum fur Luft- und Raumfahrt; DLR) provides the answers. DLR’s researchers used machine learning methods to process current aerial photographs and geodata, enabling them to determine solar energy potential for the entire stock in Germany of around 20 million buildings. Results for the whole country are publicly available at eosolar.dlr.de.

The Solar Atlas is being presented at ILA in Berlin, where DLR is showcasing its research and development work in aeronautics, space, energy, transport, digitalisation and security.

“Policy makers need precise information on the current inventory and growth potential in order to devise and implement effective strategies for expanding photovoltaic systems on roofs,” explains Anke Kaysser-Pyzalla, Chair of the DLR Executive Board.

“The satellite-derived information provided by DLR supports the energy transition and drives forward innovative products and business models. The DLR Solar Atlas shows how Earth observation can be used successfully for climate protection and the sustainable expansion of energy generation.”

Multiple terabytes of data evaluated

Within the framework of the EO Solar project, researchers from the DLR Earth Observation Center (EOC) are evaluating and combining several terabytes of data from various sources to outline the current situation in Germany. These include digital, distortion-free aerial photographs with a resolution of 20 centimetres and high-quality surface models with a resolution of one metre, provided by the Federal Agency for Cartography and Geodesy.

“To evaluate the current expansion potential for solar energy, we calculate the possible electrical output based on the hours of sunshine, radiation intensity, orientation of roof surfaces and shading from neighbouring buildings or vegetation,” says Annekatrin Metz-Marconcini, who heads the EO Solar project.

“DLR has also developed a process using artificial intelligence that enables us to identify roofs with existing solar panels anywhere in the world based on high-resolution remote sensing data. In Germany, we have included the Core Energy Market Data Register in the information that we use.” The Core Energy Market Data Register lists all registered German solar panel installations and is updated on a daily basis.

Rather than building models, EO Solar uses digital terrain models, including those generated with the help of aircraft and satellites. These models automatically take account of shading from trees and the surrounding area, and the process can be extended to countries that do not have building models. Other than the roofs of buildings, the solar energy potential of open spaces can also be calculated using the same methodology and then taken into account for planning purposes.

Solar potential identified for municipalities, districts and federal states

Existing solar panel registers for federal states, districts or municipalities often differ in the level of information included, may lack detail or be limited to certain areas. By contrast, the DLR Solar Atlas provides an up-to-date, systematic mapping of the whole of Germany and as such offers policy makers and planners alike a basis for promoting the targeted expansion of photovoltaic systems.

DLR researchers have already created a similar map for Austria as part of an ESA project. For data protection reasons, it is not possible to map solar expansion potential for individual buildings on a publicly available website in Germany, so the expansion potential is shown at municipal, district or federal state level. The publicly accessible website eosolar.dlr.de has recently been set up for this purpose.

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Solar Energy

Some countries could meet electricity needs with floating solar panels, research shows

Published

3 days ago

June 5, 2024

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Some countries could meet electricity needs with floating solar panels, research shows

by Sophie Jenkins

London, UK (SPX) Jun 05, 2024

Floating solar photovoltaic (FPV) panels could supply all the electricity needs of some countries, according to new research. The study by Bangor and Lancaster Universities and the UK Centre for Ecology and Hydrology evaluated the global potential for low-carbon floating solar arrays. Researchers calculated daily electrical output from FPV on nearly 68,000 lakes and reservoirs worldwide, using climate data for each location.

The study focused on lakes and reservoirs likely to support floating solar technology, which are within 10 km of a population center, not in protected areas, and don’t dry up or freeze for more than six months each year. Researchers based their calculations on FPV covering 10% of surface areas, up to 30 km.

Potential annual electricity generation from FPV on these lakes is 1302 terawatt hours (TWh), about four times the UK’s total annual electricity demand. The findings are published in Nature Water.

FPV systems offer several advantages over land-based solar installations, including freeing up land for other uses and keeping panels cooler for better efficiency. There is also evidence for additional environmental benefits, such as reducing water evaporation and limiting algal blooms. However, further research is needed on FPV’s overall environmental impact, and deployment decisions should consider the intended function of water bodies and potential ecological impacts.

Lead author Dr. Iestyn Woolway of Bangor University said, “We still don’t know exactly how floating panels might affect the ecosystem within a natural lake, in different conditions and locations. But the potential gain in energy generation from FPV is clear, so we need to put that research in place so this technology can be safely adopted. We chose 10% of a lake’s surface area as a likely safe level of deployment, but that might need to be reduced in some situations, or could be higher in others.”

The research shows five nations, including Papua New Guinea, Ethiopia, and Rwanda, could meet their entire electricity needs from FPV. Others, such as Bolivia and Tonga, could meet 87% and 92% of their demand. Many countries, particularly in Africa, the Caribbean, South America, and Central Asia, could meet 40% to 70% of their electricity needs through FPV. In Europe, Finland could meet 17% and Denmark 7% of their demand.

The UK could generate 2.7 TWh annually from FPV, enough to power around one million homes. The UK’s largest FPV installation is a 6.3 MW floating solar farm on the Queen Elizabeth II reservoir near London.

Dr. Woolway added, “Even with the criteria we set to create a realistic scenario for deployment of FPV, there are benefits across the board, mainly in lower income countries with high levels of sunshine, but also in Northern European countries as well. The criteria we chose were based on obvious exclusions, such as lakes in protected areas, but also on what might reduce the cost and risks of deployment.”

Co-author Professor Alona Armstrong of Lancaster University said, “Our work shows there is much potential for FPV around the world. But deployments need to be strategic, considering the consequences for energy security, nature and society, as well as Net Zero.”

The research is funded by the Natural Environment Research Council, part of UK Research and Innovation.

Research Report:Decarbonisation potential of floating solar photovoltaics on lakes worldwide