Why do we burn oil and split the atom at great risk to the planet when enough clean solar energy to power the world for 27 years falls from the sky every day? Three reasons really: 1. A daytime-only motor car with a roof the size of a swimming pool has limited market potential. 2. Static solar power costs many times more to generate than traditional grid sources. 3. The populations of areas with no access to electricity grids - solar power's most obvious market - are poor.