A contact of mine, Damon has written an exploratory guide looking at the feasibility of running a discrete part of a domestic energy system on solar electricity.
By choosing on the one hand to ignore the financial limits of solar energy while looking to create a practical solution, Damon has managed to create a usable mains independent power system.
“I’m a bit of an ‘owl’ and often work at home late into the evening and sometimes the ‘wee small hours’. My preferred working light is a mains AC anglepoise lamp, currently containing a 20W 1200 lumen CFL bulb. The aim of this project is to replace that light source with one solar-powered. “
see damon’s website: http://www.earth.org.uk/solar-PV-pilot-summer-2007.html