Thursday, 09 January, 2003

Solar Powered Cars?

While I'm on the subject of solar power, let's look at the possibility of solar powered cars.  From yesterday, we know we can get one kilowatt per square meter.  A typical car is about 15 feet long and about 7 feet wide, or about 10 square meters.  So on a sunny day I can expect 10 kW to be hitting the surface of my car.  Even assuming those fictional 100% efficient solar cells, we're only talking 13.5 horsepower (which, incidentally, is the power rating on my riding lawn mower).  A figure of 4 horsepower, maximum, is more reasonable, and even that's probably on the high side.  But reasonable performance for a practical car requires about 20 hp to be delivered to the drive train.  There simply isn't enough sunlight hitting the car, even at 100% efficiency, to power a useful car, even if the solar cells could recharge batteries while the car is parked.  See this web site for some ideas on the numbers, or do a Google search on "solar car" and see what the universities are doing.