“A solar cell on steroids”

In the late 2000s, various well-funded startups endeavored to market innovative and flexible solar materials, including thin-film technologies like cadmium telluride and organic solar cells. The expectation was that these materials would be significantly cheaper and customizable in shape.

Silicon panels, however, evolved rapidly. Efficiency improvements and plummeting prices, driven by government research, market incentives, and economies of scale, solidified their dominance.

China played a pivotal role, employing aggressive subsidies to enhance manufacturing and exports, seeking to dominate the global market. This led to significant price reductions for commercial silicon panels and diminished prospects for alternative materials.

For any new solar technology to justify the substantial costs associated with factory setup and distribution, it must excel in critical areas: efficiency, affordability, versatility, and longevity.

Perovskite shows promise in several of these aspects. A single layer could theoretically achieve 33% efficiency, and a tandem perovskite-silicon setup could reach around 43%. Higher efficiency allows for increased electricity generation from the same number of panels or similar output with reduced space and costs.

Production of perovskite modules is also expected to be less expensive. Traditional silicon panel manufacturing is complex, involving multiple steps, high heat, and precision slicing. In contrast, perovskites can be produced at lower temperatures and applied in liquid form, allowing for roll-to-roll manufacturing akin to printing newspapers.

By leveraging Bosch’s manufacturing facilities, Oxford PV aims to mass-produce silicon-perovskite cells by next year, packaging them into standard solar panel formats.

“It’s an ordinary solar cell on steroids,” Case describes.

In March, Oxford PV announced it had secured over $40 million to launch its products, bringing its total funding to around $100 million. The factory is set to produce 250 megawatts of cells annually.

Another startup, Energy Materials, based in Rochester, New York, is also exploring roll-to-roll production techniques using equipment originally designed for Eastman Kodak. This approach promises to cut production costs by half compared to traditional solar modules.

Due to its flexible, semitransparent, and lightweight nature, perovskite can be utilized in applications where traditional, heavier solar panels may not be viable—such as on windows, irregular rooftops, or even on moving vehicles.

Swift Solar, a startup affiliated with NREL, has raised nearly $7 million recently to develop tandem solar cells using two layers of perovskite, each optimized for different spectrum parts. CEO Joel Jean envisions these cells being used on drones and electric vehicles to enhance their operational range.

Unlocking new solar applications

In his book Taming the Sun, Varun Sivaram, chief technology officer at ReNew Power, suggests that advancements like perovskite technology could be critical in the quest to replace fossil fuels.

Yet, the question arises: why pursue cheaper solar solutions when silicon panels already compete effectively with coal power?

A major challenge with solar energy is that once it constitutes a significant portion of grid electricity, the value of additional installations declines sharply. Solar farms produce no energy at night, necessitating that the grid be equipped to manage total demand independently. Conversely, on sunny days, excess energy can overwhelm the system, leading operators to curb production by reducing prices, sometimes below zero. This undermines the profitability of solar plants, diminishing incentives for further development and fossil fuel reduction.

Sivaram and Shayle Kann, in a 2016 Nature Energy paper, concluded that to maintain economic motivation for new projects, solar generation costs would need to drop to 25 cents per watt. Current all-in costs for the most affordable commercial systems stand at $1.06 per watt, largely due to high installation and hardware costs. Achieving such a drastic reduction necessitates not only cheaper solar cells but also lightweight and flexible designs for easier deployment. Perovskites represent the most promising candidate for this advancement, according to Sivaram.

Affordable solar energy could also lower costs for innovations like seawater desalination, carbon capture technologies, or electrolysis plants converting surplus energy into hydrogen fuel.

“This opens up a plethora of new applications we hadn’t considered before,” Sivaram states.

The durability dilemma

The most significant concern regarding perovskites is their longevity. Efficiency is irrelevant if the material deteriorates within months or years; current perovskites have shown susceptibility to degradation when exposed to UV light and moisture.

This presents a critical issue for a material intended to endure under sunlight for decades. Should companies launch perovskite panels that fail prematurely, it could tarnish the material's reputation, even if more resilient versions are later developed.

Presently, Oxford PV's market strategy hinges on the performance and appearance of its perovskite-silicon cell, which includes encasing it in glass for added durability.

The company has invested significant effort into enhancing material stability, utilizing computational modeling and extensive testing to identify optimal compositions from a vast array of possibilities. While their perovskite formulation remains proprietary, CEO Frank Averdung expresses confidence, stating, “We have resolved the reliability issue. We are prepared to transition into manufacturing mode now.”

James Temple is the senior editor for energy at MIT Technology Review, focusing on renewable energy and technology's role in combating climate change. Previously, he held senior positions at Verge and Recode, and enjoys hiking and capturing California's landscapes in his spare time.