This Major Perovskite Breakthrough Could Change Solar
Alex Kimani

Qcells, a subsidiary of South Korea’s giant conglomerate Hanwha Corp, has set a world record for the efficiency of a large-area silicon solar cell with a top layer of perovskite, a development that could dramatically shrink the size of projects and slash costs. Qcells says it has achieved cell efficiency of 28.6% on a large commercial-sized cell known as an M10 using the technology, considerably higher than 27% efficiency for crystalline silicon cells and around 21% for traditional commercial silicon solar panels. To be fair, China's Longi has achieved efficiency breakthroughs above 30%; however, that was for much smaller cells.

"If you have 100 solar panels in the field, but you can get the same power output for only 60 or 80 of them, now you're digging less holes, you're using less rails, you have less labor to install it," Danielle Merfeld, Qcells' chief technology officer, told Reuters.

Qcells’ discovery comes at a time when extensive land use by large solar projects is increasingly becoming a major challenge. For instance, California's Solar Star Project is among the largest solar energy facilities in the world, boasting 1.7 million panels spread over 3,000 acres north of Los Angeles. In comparison, a natural gas power plant located 100 miles south of Solar Star produces the same amount of energy on just 122 acres.

High-Performance Perovskite 

Silicon panels pretty much rule the solar energy sector, with more than 90% of panels manufactured using the versatile element. Si PV cells have their advantages: They’re quite robust and relatively easy to install. Thanks to advances in manufacturing methods, they’ve also become quite cheap, especially over the past decade, particularly the polycrystalline panels constructed in Chinese factories.

However, they still come with a major drawback: Silicon PV panels are quite inefficient, with the most affordable models managing only 7%-16% energy efficiency depending on factors like placement, orientation and weather conditions. Indeed, solar cells have been around for more than six decades yet commercial silicon has barely scraped into the 25% range, maxing out at a theoretical 30%. This sad state of affairs is due to the fact that Si panels are wafer-based rather than thin-film, which makes them sturdier and durable but the trade-off is a sacrifice in efficiency.

To meet the world’s rapidly growing energy appetite--and achieve the kind of de-carbonization goals that would help slow the impact of climate change--it would actually take hundreds of years to build and install enough silicon PV panels. Obviously, this is way too slow to be practical for achieving climate goals. For years, scientists have experimented with alternative crystal formations that would allow panels of similar size to capture more energy. Until now, few designs emerged that were commercially viable, particularly thin-film cells that could theoretically achieve much higher levels of efficiency. Thin-film PV panels can absorb more light, and thus produce more energy. These panels can be manufactured cheaply and quickly, meeting more energy demand in less time. There are a few different types of thin-film out there, all of them a little different from standard crystalline silicon (c-si) PV panels. 

Amorphous silicon (a-Si) panels are the oldest form of thin-film: a chemical vapor deposits a thin layer of silicon onto glass or plastic, producing a low weight panel that isn’t very energy efficient, managing 13.6%. Then there’s cadmium telluride (CdTe) panels, which uses the cadmium particle on glass to produce a high-efficiency panel. 

The drawback is that metal cadmium is toxic and difficult to produce in large quantities. 

These panels are usually produced using evaporation technology: the particles are superheated and the vapor is sprayed onto a hard surface, such as glass. They are thin, but not as dependable or durable as c-si panels, which currently dominate the market.

Perovskite has so far proven to be the most promising and has now managed to break the efficiency glass ceiling. Perovskites are a family of crystals named after Russian geologist Leo Perovski, “perovskites.” They share a set of characteristics that make them potential building blocks for solar cells: high superconductivity, magnetoresistance, and ferroelectricity. Perovskite thin-film PV panels can absorb light from a wider variety of wave-lengths, producing more electricity from the same solar intensity.In 2012, scientists finally succeeded in manufacturing thin-film perovskite solar cells, which achieved efficiencies over 10%. But since then, efficiencies in new perovskite cell designs have skyrocketed: recent models can achieve 30%+, all from a thin-film cell that is (in theory) much easier and cheaper to manufacture than a thick-film silicon panel.

Earlier in the year, Longi announced it had achieved a power conversion efficiency of 34.6% for a perovskite-silicon tandem solar cell, a new world record beating the company’s previous record of 33.9% set in November 2023. The European Solar Test Installation (ESTI) certified the results in June this year.

“We achieved this result by optimizing the thin film deposition process of the electron transport layer, developing and using high-efficiency defect passivation materials, and designing and developing high-quality interfacial passivation structures,” the company said in a statement, without providing further details.

Longi has broken the world record for solar cell efficiency 16 times since April 2021. The company’s latest world beaters have actually surpassed the Shockley-Queisser (S-Q) theoretical efficiency limit of 33.7% for single junction solar cells.

By Alex Kimani for Oilprice.com

 

 

 

Alex Kimani is a veteran finance writer, investor, engineer and researcher for Safehaven.com. 

 

 

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