The solar powered car is an idea whose time may be a long while coming – I’m sorry, I have to say it, as it’s based on some fundamentals. That said, for the enthusiast there are already solar powered cars available, if you can live with the restrictions.
The solar powered car derives its input energy from the sun, and stores it in batteries, at which point it becomes more akin to the electric car. In fact, solar cars can be plugged in to recharge if the amount of time or exposure to sun is not sufficient for the frequency of use required. Because it needs input from the sun, and the sun produces about 100 Watts per square foot, there is a physical limit, regardless of technology, to how much power is available to drive the car.
The regular solar panel is 8% – 14% efficient, meaning that it converts that percentage of the sun’s energy into power. From this, we get the often used rule of thumb that you get about 10 Watts per square foot from a panel. Now, there are 746 Watts to one horsepower – so for each horsepower you want from the car, you need about 75 square feet of conventional solar panels, if you don’t want to run down the batteries.
Of course, you won’t be driving all the time (although there may be some driving at night, when you will be getting no energy replaced in the batteries) – but it’s not unusual to talk of over 100 horsepower in a modern saloon car.
Having set out the basics, there are commercially available cars coming on the market, and they are very usable for some purposes. A French company called Venturi seems to lead in the field –The Venturi Eclectic and the Venturi Astrolab are two solar electric vehicles.
The Eclectic is described as avant-garde, and it is certainly unusual, with a full-size lid of solar panels. It has a range of about 30 miles, recharges by solar about 4 miles each day, and is a city car.
The Astrolab is an open sports car, with the flat top reserved for the solar cells, and seats two. It has a top speed of 75 mph and range of nearly 70 miles, with a daily solar recharge of about 11 miles. Its solar cells are 21% efficient.
Perhaps the best answer to having a solar powered car is to buy one of these, and to have a solar electric system on your garage roof to provide the power for recharging!