Solar cars on the distant horizon

Wouldn't it be nice if you could buy a normal looking car that was completely powered by solar cells covering its surface. If you follow the World Solar Challenge, in which self-sufficient solar cars speed across Australia, then you might think that it won't be long before this technology reaches the mainstream. However, there's still a huge gap between the energy that can be harnessed from the sun and the internal combustion engine.



In the chart, the solar value is for a car covered in 6 square metres of the most advanced solar cells on the planet (almost reaching the efficiency of those on the International Space Station). The Toyota Yaris is the lowest-powered small car that I'd still find fun to race off from traffic lights.

Bear in mind that most of the time these cars don't need full power. So, could I retrofit a Yaris with batteries and solar cells for my daily 15 minute commute?

To make things easy, I'll plug the car into the mains overnight to recharge, but only enough to get to work. I then leave it out in the sun for 8 hours, filling the batteries with 2 * 8 = 16 kWh. To get home with conservative driving techniques I need about 40 kW for 15 minutes, ie. 40 * 0.25 = 10 kWh. Woohoo! I make it home, with power left for the following day. Let's hope that it won't take too many years for the unrealistic assumptions in these calculations to be rectified with technology.