Toyota Eyes Perovskite Solar Cells For Solar Car Of The Future

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Fans of perovskite solar cell technology have been promising the moon, and stakeholders are increasingly confident that it will deliver. Among them is Toyota, which has just tapped its Woven Capital branch to spearhead a new ¥5.5 billion round of funding in the perovskite solar startup EneCoat Technologies. If you’re thinking the solar-powered electric car of the future is coming, that’s a good guess, because EneCoat lists mobility applications among its areas of focus.

New Solar Cells For The Solar Car Of The Future

The idea of pasting solar cells on an electric vehicle seems reasonable enough. The surface area is relatively small, but a typical car can spend many hours outside, baking in the sun. The advantage would be less reliance on EV charging stations, and more use of free energy from the sun.

One key challenge, though, is weight. After all, what’s the point of festooning an electric car with solar panels if their weight results in a drag on battery range. In addition, conventional silicon solar cells are stiff, making it difficult to take advantage of curved surfaces.

Some firms are not waiting for new, lightweight and flexible solar cells to come along. The US startup Aptera, for example, is leveraging lightweight materials, aerodynamics, and an autocycle configuration to concoct a new EV powered by onboard solar panels. Another solar car startup working along similar lines is the Dutch firm Lightyear.

Other solar car hopefuls have fallen by the wayside, but the Canadian company Worksport has come up with a partial solution. The company is marketing a tonneau cover for pickup trucks with built-in solar panels, which can be used by gasmobiles and EVs alike for auxiliary power (see another use for solar panels here).

Solar Cells & The Return Of The Plug-In Hybrid

Automakers like Toyota have also begun to take a serious look at introducing solar cells on the semi-flat surfaces of vehicle rooftops. Back in November of 2022, Toyota unveiled its 2023 Prius Prime plug-in hybrid series with optional rooftop solar panels that can recharge the battery when the car is parked.

EV purists may scoff at the hybrid solution, but Toyota has been holding the hybrid torch for years. All that hard work paid off last year, when MotorTrend tapped the Prius hybrid as its 2024 Car of The Year despite admittedly stiff competition from pure EVs.

MotorTrend buried a mention of the solar roof way, way down near the end of a detailed review. “Aside from the optional solar roof, the Prius Prime charges via an onboard 3.5-kW charger” was the extent of the attention.

The Perovskite Solar Cell Difference

If all goes according to plan, future reviews will be paying lots more attention. Toyota’s new stake in EneCoat gives it a ringside seat to the next generation of super thin, ultra-flexible, lightweight perovskite solar cells.

CleanTechnica has been spilling plenty of ink on perovskite solar cells, which deploy relatively inexpensive lab-grown crystals based on the superior solar conversion properties of the naturally occurring mineral perovskite. Prepared in a solution, perovskite solar cells can be sprayed, painted, or printed on a wide range of surfaces that are inaccessible to conventional silicon technology (see more perovskite background here).

There being no such thing as a free lunch, initial attempts to harness the power of perovskite in the early 2000s literally fell apart, as the material succumbed to ambient humidity. Nevertheless, science loves a challenge and EneCoat is among those coming up with a solution.

“In the past, perovskite structure materials were synthesized using inorganic materials, but in recent years, it’s become possible to create organic-inorganic hybrid perovskite films using a wet process based on organic chemistry,” the company explains. “EneCoat technologies is also utilizing this method to develop and manufacture our ultrathin perovskite solar cell films.”

The company deploys an energy efficient, low-temperature coating process to fabricate a uniform film. This process is compatible with the high volume, fast throughput roll-to-roll process that revolutionized the printing industry back in the 1800s, which partly explains why Toyota is so excited about the startup. The US Department of Energy is also among those looking forward to a roll-to-roll makeover for the solar industry.

It’s not just Toyota. In a press release emailed to CleanTechnica, Woven Capital notes that it spearheaded the Series C funding round for EneCoat along with INPEX and Mitsubishi HC Capital. “Existing investors Mirai Creation Fund III and Kyoto University Innovation Capital participated in the round, bringing the total funding raised to over 8 billion yen,” Woven also explained. That’s more than $50 million, for those of you keeping score at home.

For the record, Woven also lists Mitsubishi UFJ Capital, Mitsubishi HC Capital, Kyoto Capital & Partners, ShinMaywa Industries, Nishimatsu Construction, The Chugoku Electric Power, Hakuto, and Chushin Venture Capital Fund VI among the Series C participants.

Today Toyota, Tomorrow The World For Perovskite Solar Cells

Beyond mobility applications, perovskite solar cell stakeholders are looking forward to applying their technology anywhere and everywhere.

In the meantime, a sort of halfway measure has emerged in the form of hybrid perovskite-silicon solar cells, with perovskite helping to boost efficiency and trim costs while silicon takes care of the durability issue.

That technology is already poised to hit the market. Last month, for example, the UK firm Oxford PV reported that is has created a hybrid solar module scaled for residential use with an”unprecedented” solar conversion efficiency of 26.9%.

While falling short of an all-perovskite solar cell, Oxford PV’s residential module illustrates how perovskite solar cells can accelerate the global solar movement.

As described by Oxford PV, there is a solar conversion efficiency gain of 1.6% between its new hybrid module and silicon modules alone, which generally weigh in at 25% at the high end.

“A gain of 1.6% conversion efficiency may seem like small potatoes, but with greater conversion efficiency comes the same amount of solar power in a smaller footprint,” CleanTechnica observed on June 24. “That can translate into lower costs for manufacturing, transportation, and installation.”

“The increased efficiency also means that fewer solar panels are needed to provide the same power output. That could open up the market to smaller or partially shaded rooftops,” CleanTechnica added.

The global solar industry has come a long way since the first silicon solar cells were invented back in 1954 — right here in the US, as a matter of fact. Now imagine what solar stakeholders can accomplish with a new, less costly, and more versatile material in hand. If you have any thoughts about that, drop a note in the comment thread.

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Photo (cropped): Solar cars are beginning to appear on the market, and Toyota’s Woven Capital growth fund is banking on new perovskite solar cells to keep the momentum going (courtesy of Toyota).