While perovskite has the ability to reach high efficiency (The world record For a perovskite cell only a little over 25%), most of today’s best performing perovskite cells are very small – less than an inch.
Expansion makes it more difficult to reach potential efficiency limits. At the moment, the efficiency of Saule panels, which are a meter wide, is about 10%. This dwarfs with similarly sized commercial silicon panels, which typically reach around 20% efficiency.
Olga MalenkevichSaule’s founder and chief technology officer says the company’s goal was to get a perovskite-only solar cell out of the home, and lower efficiencies wouldn’t matter if the technology was cheap enough.
Saule is trying to go where silicon solar panels can’t: to surfaces that can’t handle the weight of heavy laminated glass panels, or to more specialized applications, such as solar-powered canopies, which the company is currently testing.
As Saule launches thin-film products for more niche applications, other companies hope to beat silicon, or at least join it at their own game. UK based Oxford BV Combines perovskite into files A mixture of perovskite and silicon cells.
Because 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 composite cells to reach higher efficiency than silicon alone.
The cells mounted in Oxford PV are heavy and rigid, like only silicon cells. But because they are of the same size and shape, the new cells can easily fit into panels for rooftop arrays or solar farms.
Chris KissOxford PV’s chief technology officer says the company is focusing on lowering the standard cost of electricity, a metric that impacts lifelong system installation and operating costs. While layering perovskite over silicon adds to the manufacturing cost, he says the standard cost of a composite cell should fall below silicon over time because these new cells are more efficient. Oxford has set several world records in efficiencies of this type of cell in the past few years, the most recent of which reached 29.5%.
Microquanta Semiconductor, a Chinese perovskite company based in Hangzhou, is also taking some signals from silicon solar cells. The company manufactures panels from rigid cells laminated with glass made of perovskite.
Microquanta’s pilot plant opens in 2020, and capacity is expected to reach 100 megawatts by the end of the year, he says Puyi yangHead of the company’s technology department. The company has demonstration panels installed in many buildings and solar farms across China.
A solution for stability
Perovskite stability improved from minutes to months within a few years. But most silicon cells installed today have a warranty of about 25 years, a goal that perovskite may not yet be able to reach.
Perovskites are particularly sensitive to oxygen and moisture, which can interfere with the bonds in the crystal, preventing electrons from effectively moving through the material. Researchers are working to improve the life of perovskite, by developing less reactive perovskite recipes and finding better ways to package them.
Oxford PV, Microquanta and Saule say they have solved the stability issue, at least well enough to sell their first products.
The long-term performance in solar cells is usually estimated by rapid testing, placing the cells or panels under extremely stressful conditions to simulate years of wear and tear. The most common test suite for external silicon cells is a series called IEC 61215.