Testing perovskite solar cells in the lab used to require a decent pair of running shoes. The materials fell apart so quickly that scientists would bolt from where they made the cells to where they tested them, trying to measure their performance before the cells degraded in their hands—usually within a couple of minutes.

Perovskites have long enchanted researchers with the promise of producing inexpensive, ultra-efficient solar cells. And now several companies are making major strides toward producing commercial perovskite solar cells at scale.

But the materials’ instability has threatened to derail their path to rooftops and power plants. Though a few companies say they’ve solved the challenge, at least well enough to bring preliminary products to market within the year, some researchers are still skeptical.

“People want me to say ‘I know for sure this is going to be stable, and it’s going to be efficient and we’re going to conquer the world,’” says Joseph Berry, who leads the perovskite research program at the US National Renewable Energy Laboratory. “And part of me believes that, but part of me as a scientist says, ‘I don’t have the data.’”

Soaking up the sun

Perovskites are synthetic materials, inexpensive and relatively simple to produce even in large quantities. Common perovskites used in photovoltaics are typically something like methylammonium lead halide, but the perovskite family includes thousands of materials that share the same crystal structure. Coated onto a flexible base, they can produce thin-film solar cells that are light and bendable.

While several new photovoltaic materials have emerged in recent decades, none has made much of a dent in the market, which is dominated by silicon. It is found in around 95% of existing solar cells.

Some perovskite companies, like Saule Technologies in Warsaw, are trying to leave silicon behind altogether. The company, founded in 2014, developed an ink-jet printing process for manufacturing perovskite solar cells encased in a flexible plastic. A panel containing Saule’s cells is about a tenth as heavy as a silicon panel of the same size.

In May, Saule opened a factory that can produce around 40,000 square meters of panels annually. That’s enough to generate around 10 megawatts of power (some factories that produce silicon cells are hundreds of times larger). 

While perovskites have the potential to reach high efficiencies (the world record for a perovskite-only cell is just over 25%), most of the best-performing perovskite cells today are tiny—less than an inch wide. 

Scaling up makes it more difficult to reach the potential efficiency limits. Right now, Saule’s panels, which are a meter wide, reach around 10% efficiency. This is dwarfed by commercial silicon panels of similar sizes, which typically hit around 20% efficiency. 

Olga Malinkiewicz, Saule’s founder and chief technology officer, says the company’s goal was to get a perovskite-only solar cell out the door, and the lower efficiencies won’t matter if the technology is cheap enough.

Saule is trying to go where silicon solar panels won’t: to roofs that can’t handle the weight of heavy glass-encased panels, or to more specialized applications, such as solar-powered blinds, which the company is currently testing.

While Saule is launching thin-film products for more niche applications, other companies hope to beat, or at least join, silicon at its own game. UK-based Oxford PV is incorporating perovskites into combination perovskite-silicon cells.

Since silicon absorbs light toward the red end of the visible spectrum, and perovskites can be tuned to absorb different wavelengths, coating a layer of perovskite on top of silicon cells allows combination cells to reach higher efficiencies than silicon alone.

Oxford PV’s combination cells are heavy and rigid, like silicon-only cells. But since they’re the same size and shape, the new cells can easily slot into panels for rooftop arrays or solar farms.

Oxford PV combines perovskite and silicon to create high-efficiency solar cells. OXFORD PV

Chris Case, Oxford PV’s chief technology officer, says the company is focused on lowering the levelized cost of electricity, a metric that factors in a system’s installation and lifetime operation costs. While layering perovskites

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By: Casey Crownhart
Title: Can the most exciting new solar material live up to its hype?
Sourced From: www.technologyreview.com/2021/06/29/1027451/perovskite-solar-panels-hype-commercial-debut/
Published Date: Tue, 29 Jun 2021 09:30:00 +0000

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