Swift Solar nabs $27M to chase solar efficiency holy grail: perovskites

Generating clean electricity from solar photovoltaic technology is the success story of the clean energy transition so far, but entrepreneurs and investors are still plumbing the science for improved performance and cost.

Startup Swift Solar banked a $27 million Series A financing round this week to commercialize a new light-absorbing class of crystalline materials known as perovskites, which have the potential to improve upon today’s utterly dominant technology — crystalline silicon. 

It’s not the first firm to have this idea. Over the last decade, billions of dollars in venture and corporate funding has been spent chasing the goal of manufacturing high-efficiency, non-silicon solar modules using materials including perovskites. America’s First Solar is the world’s only non-silicon solar manufacturer to survive and grow to multi-gigawatt capacity. (Incidentally, First Solar, which uses a technology based on thin-film cadmium telluride materials, acquired a perovskite startup last year.)

Over the last 10 years, the average efficiency of standard silicon solar modules — the percentage of solar energy converted into useful energy — has steadily increased from about 15 percent to more than 20 percent. Solar efficiency is forecast to reach 23 to 24 percent by the end of this decade. It’s an inspirational technological progression, but one that is now butting up against the physical limits of these materials.

Rather than go head-on against the companies — most based in China — that are squeezing every drop of efficiency out of silicon modules and producing them at staggering scale and low cost, Swift and a number of other firms are looking to blow through the efficiency limits of standard modules using perovskites. To do so, these firms aim to create a ​“tandem cell,” layering perovskite atop a conventional silicon cell. 

Joel Jean, Swift’s CEO and co-founder, as well as Scott Graybeal, CEO of startup Caelux, told Canary Media that a perovskite layer could boost relative efficiency enough to produce modules at 27 to 29 percent efficiency. More efficient solar panels means that more electricity can be produced from the same acre of land or rooftop, making solar power — already the cheapest form of electricity in history — even cheaper.

Perovskites are also promising because they can be produced from earth-abundant materials and have the potential to be recycled, and perovskite cells can be manufactured using lower-cost and lower-temperature printing processes than the complex gear required to produce silicon modules.

Yet questions remain about perovskite modules’ lifetimes and stability. Properly characterizing the long-term reliability of a perovskite module to the satisfaction of risk-averse insurers and project developers will take years of investment, deployment, and industry standardization. In contrast, silicon is one of earth’s most studied elements; its long-term behavior and failure modes are already well understood, to the point where it allows module producers to offer 30-year-plus guarantees on their products.

While perovskite solar might have its virtues, its story so far has been defined more by ambitious claims than by real-world successes. 

In 2016, Swift co-founder Sam Stranks said in a TED talk that perovskites would be set to make their commercial debut in 2017. In 2021, Frank van Mierlo, the former CEO of perovskite firm Cubic PV, bet this reporter that ​“the solar market will see 2 gigawatts of tandem solar in the marketplace by the end of 2022.” In 2022, Graybeal of Caelux told Canary Media that he expected the company’s tandem module, along with a 25-year warranty, to launch into the marketplace in the second half of 2024.

There are currently zero gigawatts of perovskite-related solar modules in the market. 

For its part, Swift aims to build a U.S.-based factory to manufacture its solar modules in the next two or three years, according to Joel Jean, co-founder and CEO, and has raised more than $40 million in total to chase this goal. 

Swift’s recent round was co-led by Eni Next and Fontinalis Partners along with new and existing investors including Stanford University, Good Growth Capital, BlueScopeX, HL Ventures, Toba Capital, Sid Sijbrandij, James Fickel, Adam Winkel, Fred Ehrsam, Jonathan Lin, and Climate Capital. Swift has also landed more than $16 million in federal and state grants. Founded in 2017, the firm is a spinout of MIT, Stanford University, and the National Renewable Energy Laboratory.

A wave of startups beyond Swift are developing perovskite materials across a wide range of device architectures and manufacturing processes, including BlueDot Photonics, Beyond Silicon, CubicPV, Energy Materials, Microquanta Semiconductor, Oxford PV, Saule Technologies, SoFab Inks, Tandem PV, Verde Technologies, and UtmoLight.

But if we’ve learned anything about commercializing a new photovoltaic manufacturing process, it’s that success will take longer than expected. Meanwhile, silicon modules will continue to slowly improve on cost and performance every year, chipping away at the value these alternative technologies have presented in the first place.