Thanks for the link Keef I'd thought along similar lines myself but using a Fresnel lens is a great solution.
The day will come when sustainable distributed power systems will be adopted because; in the long run there is no alternative. The power companies and governments have a vested interest in keeping us dependent on centralised power supply the utilities because they have an unwritten cartel and the authorities because they want to be able to cut off our supplies easily when we get stropy. In the UK the whole national grid is controlled from 2 sites, which in an age of terrorism is insane.
Imagine a system with thousands of small sustainable generation points, contributing power to a grid with relatively small local energy storage systems to smooth out supplies and cope with variable demand. It would be more flexible and reliable but almost impossible to use as a weapon of extortion.

PP