The sun generates an amazing amount of energy that can be obtained through solar panels. Why haven’t we seen solar powered electric cars in showrooms yet? Engineering Explained host Jason Fenske has a few reasons to be skeptical about solar-powered cars.
The rays of the sun offer a lot of potential energy. If you cover the roof of a Tesla Model 3 with solar collectors, you could in the best case bring in up to 12 kilowatts of continuous power, Fenske calculated. That means, as long as the sun is shining, under ideal conditions you can drive indefinitely at a constant speed of 100 km / h.
Those solar panels could also charge a 75-kilowatt-hour battery in 6.25 hours so you can keep driving at night, Fenske said. That in turn assumes ideal conditions.
However, the real conditions are not really ideal. Only about 55% of the sun’s energy reaches the earth’s surface; the rest is reflected or absorbed by the atmosphere.
Aptera Sol Alpha prototype
The efficiency of solar panels is also a limiting factor. The most common panels have an energy conversion limit of 33.7%, which means that most of the sunlight that hits them will not be converted into electricity (although there are ways to increase this limit).
The curvature of the earth can also affect the efficiency of solar panels, noted Fenske. This means that only a small area of the earth’s surface is facing directly towards the sun at any given time. Everywhere else, solar panels are tilted slightly away from the sun, which limits their ability to generate energy.
Taking these inefficiencies into account, a model 3 covered with solar modules could only generate 1.5 kW, Fenske calculated. At that rate, it would take 8.3 days to just charge the Tesla, he noted. Because of this, solar panels have been limited to providing additional power in cars like the Hyundai Sonata Hybrid or for purpose-built racing vehicles for events like the World Solar Challenge.
However, some companies are still trying to bring solar cars to market. One of them is Aptera, which claims that his tricycle can get all of its energy from the sun and therefore does not need to be charged. Fenske said the math for this was checked, but the Aptera hasn’t gone into production yet, and it’s a tiny two-seater too, so not exactly a mainstream product.