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Jul 11, 2023

Why Doesn’t Every Electric Car Have Solar Panels?

The large transparent roof on the Prius returns, and the solar panel option will

The large transparent roof on the Prius returns, and the solar panel option will now charge up the ... [+] main battery as well.

It seems like a complete no-brainer: Heat and light from the sun's reliable daily routine pours down upon us, and solar panel technology has been turning light energy into electricity for decades, so why isn't every electric car on the road topped with some sort of solar power collection device to scoop up that free juice instead of requiring owners to plug them into an increasingly stressed power grid? Cost? Conspiracy? Both? Maybe some of the former, but the real reason: Science.

The basic reason is, for lack of a better term: acreage - or the lack of it. Without getting into the technical nitty gritty, there just isn't enough space for a large enough solar collection system (often called an "array") on top of cars to make a meaningful contribution to the charging needs of the battery. If there was, every EV maker on Earth would likely include an array (or offer it as an option) on every car sold.

Toyota's team has done a good job of sharpening the car's style while retaining interior room and ... [+] some callbacks to the older models.

However, that may be about to change - and again, thanks to science, but also somewhat to consumer demand and a re-think by some automakers. I believe we are going to see more vehicles with solar power systems in the future.

Toyota announced their next-generation Prius (above and top photo) will include a solar roof option. Previous generations also had this as an option, but the solar power only did things like run the A/C or a cooling fan when the car was parked somewhere hot; it didn't charge the battery (it is a hybrid, after all). Now it will. What changed? Previously, the solar array could not generate enough power (voltage) to match the battery voltage; Toyota has clearly rethought that approach (the technology to remedy that problem is readily available).

Will parking your Prius in the sun all day give you a full charge when it's time to head home from work? Not by a long shot, but it could add a small number of miles to the range, and if your commute is a small number of miles (and for many people that's the case), you could essentially drive "for free" on that bit of range boost. And if the car sat for several days in the sun (most personal cars sit parked for 95% of their lives), then it can add up.

Bottom line: It's free power you don't have to pay for. That's compelling for many consumers, and therefore for automakers. But for now, the amount of power that can be generated by a small panel is... small. But as noted, that may still work for some electric/hybrid car buyers looking for any way to extend range and stay out off the gas engine, at least in the Prius.

The Sono Motors Scion is covered in hidden solar panels and can add a lot of miles of range while ... [+] parked.

Another approach is to cover the entire vehicle in solar collection tech, such as the Sono Motos Sion (not to be confused with the defunct Scion brand), a four-seater (above) which charges the car's smaller battery if sunlight hits it from any angle. Sono claims 305km (190 miles) of range on a full charge, with the 456 solar cells built into the car's body providing 245km (145 miles) of range under ideal conditions - all without plugging it in to charge. The solar cells are seamlessly integrated into the car's exterior, although that does limit color choice or repaint options. The car will also charge to 80% in under an hour from a plug-in charger, and Sono says the Sion will also feature V2H/V2G capabilities for powering your home or plug-in A/C things if need be. The car is in pre-production at this time but it could be a peek at one future for electric vehicles that don't necessarily need to be near a grid-connected charger to juice back up.

The Lightyear 0's top-facing surfaces are solar panels, while ordinary painted panels keep the car ... [+] looking familiar - if exotic.

The Lightyear 0 (Zero), strikes a compromise with painted body work and a sleek profile (above) but with five square meters of integrated solar panels on the top and hood. According to Lightyear, power collected by its larger solar system system can add up to 43 miles of range per day, or nearly 7,000 miles of range per year on sunlight, close to the national average of driving 10,000 miles per year in the U.S. Best of all, the cars are now in production. Progress has its price; you’ll need to budget about $250,000 for the Lightyear 0.

Another interesting idea is the Scout Solar and Mark II Solar from Wink Motors. These small, speed-capped mini-cars start at about $10,000 and are dedicated urban vehicles that top out at 25mph, and since they have a small battery (which gives 60 miles of range), a solar panel atop the car can add quite a bit of range while it's parked.

The tiny Wink Motors Mark 2 Solar actually seats four people and can add a lot of range through the ... [+] large rooftop solar panel. Top speed is 25mph.

Give it long enough, and it can completely charge the car's battery. The Wink machines (above) are in production now and headed for America, watch for their debut soon (and here's a longer story about them).

On the other end of the spectrum, we have electric trucks - and trains. Semi haulers from Tesla and others will have huge batteries, but what if the roof of the trailer was a big solar array? There's a lot of real estate atop a 53-foot trailer, even more if the EV semi is hauling two of them. Trucking is always a delicate dance when it comes to fuel, and if solar-topped trailers could add even single-digit percentage gains in range or recharging time, in aggregate, the energy and time savings would equate to huge amounts of money saved.

Beyond that, the same idea could work for trains. Most people are unaware that the diesel locomotives pulling freight around the world are actually "electric vehicles;" the diesel fuel runs a generator that powers the huge electric motors that drive the wheels. They were essentially the first gas/electric hybrid vehicles. What if each boxcar had solar power collection panels on top? Even for one train, connected in parallel, that amount of solar capture capability would generate a huge amount of power the engines could harness either in a hybrid storage system (batteries + diesel), or power the train in the flat solely on solar power. The fuel savings would be immense over time.

Lastly, all these solar collection systems could also be tapped into the grid, changing our power system from an on-demand type system that we have now to a storage-based system (using large batteries) that could absorb energy usage spikes using V2G technologies - a huge change. Solar power pundits incorrectly claim that we would have to cover the earth in solar panels like some sci-fi movie planet (Corusant) to meet our energy needs from solar power alone, but that's highly inaccurate. A solar farm this size would be able to do the job, but if you break up that solar collection area into many, many tiny small parts, in aggregate, a world filled with solar-collecting cars, trucks, trains and maybe even aircraft would more than add up to the worldwide energy needs. It will just take the willingness to do it. The technology is readily available today.

Some things are for certain: Solar panels will continue to improve in terms of efficiency, and the cost will continue to come down as well. Battery tech will continue to improve, eventually reaching charging time parity with refueling using liquid fuels - or maybe be even faster. One thing for certain is that we are living in the early years of the EV revolution, and like the early years of internal combustion vehicles, technologies, infrastructure and costs with continue to improve through market forces, innovation, refinement and new ideas. For the immediate future, most electric vehicles will still require a high-powered charging system connected to the grid or a home-based power supply, but the inclusion of solar arrays on vehicles in aggregate could have a profound effect on how power grids work, and on the range capabilities of electric vehicles of all types, not just cars.