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20 September 2019

Toyota onboard solar cell not enough to run cars forever

Toyota has not been early enough into the EV race, but for a brief time, it led the rankings on hybrids before it realized it would have to play catch up on batteries and has had to contract for batteries for the next era of car transport.

But now that the largest car company in the world has awakened to the problem, it may have embraced the perfect strategy in trying to bring back to life an idea that has been universally rejected – using onboard solar to power a car.

It is neither new, nor Earth shattering as an idea, but companies have recently begun taking a second look – for Toyota is it the long term fear of being in hock to Chinese battery technology, in what is currently the key technology behind EVs, that is perhaps powering the idea.

All it has said so far is that it will put solar panels on the roof of a few Prius hybrids, and test them. Actually it will put them on the hood, roof, rear window, and spoiler, but not the sides or back. It has selected some of the most efficient solar panels in the world from Sharp, which reportedly capture 34% of the light hitting them, usually only reserved for satellites, where expense is no object and performance is everything.

Today new solar panels are moving up from around 23% energy conversion to around 28%, and for Bifacial that threatens to go even higher, although you can’t really use bifacial panels on a car. Perovskite manufacture could bring the cost of such panels right down too, and the plan is to find out what is possible today, and then worry about how to bring the costs down later.

Sono Motors will soon introduce its Sion range of vans which add 34 kilometers a day from solar – but those panels are all over the van, not expensive, but on the roof, the hood, the side and back panels. So this is not about Toyota being first, it is perhaps about it being the first among large car manufacturers, to offer much the same.

The experiment was signaled in July and has just been added to with some performance data now it has been under trial in Tokyo. Sharp said at the time that the solar panels had a rated power generation output of around 860W.

Its experience shows a far better outcome than the Sono, with something approaching 35 additional miles (56 km) to the Prius range when the solar is operational as it drives around, and just 27 miles (43 km) when just parked. The release mentions the fact that recently the Fraunhofer Institute unveiled a new solar panel which can be colored to match the paint of any car.

One of the nicest things about this is if you run out of battery by the roadside, instead of waiting for roadside emergency to come and charge you up, you can just wait for the solar panels to give you enough energy to get to the nearest charge point. This will certainly wage war against range anxiety.

Given that the average car is driven about two hours a day, a total of around 27 miles, and sits idle for 22 other hours, many of them in sunlight, this may extend the lifetime of the hybrid, using gasoline only for long journeys, and running decarbonized for large parts of the month.

There are new technologies coming in solar, but the only one that holds much promise of anything above 34% is one that is at least 5 years out, which converts heat into light and harvests that, so it is unlikely that any vehicle will be able to be entirely driven by solar power, and it looks like the next stage is to integrate it into a conventional EV battery and use it to top up charge point delivered electricity, rather than gasoline power.

Toyota now seems hell bent on catching up the lead it once had in technology,  but to do that entirely successfully it would have to start making its own batteries and not relying on batteries from BYD and CATL, and is in partnerships with Panasonic to create its own battery technology, which means it is very close to the key battery provider for Tesla.