nice summary of solar in the UK

http://www.envocare.co.uk/solar_energy.htm

talks about the need for storage to deal with the variability in supply (seasons, throughout the day etc.)
mentions IEE Review, 'Let the Sun Shine In', February 2006 for recent developments
also mentions Stirling Engines:

the Stirling Engine operates with two (or more) cylinders with pistons connected to a crankshaft. One of the cylinders is heated on the outside and the other cooled. The volumes within the cylinders are interconnected and it is a sealed system; the working gas is made to move backwards and forwards between the hot and cold sections. The clever mechanism of the Stirling cycle produces rotary motion and at the same time moves heat from one location to another. The original device was invented in the early 19th century as a safe alternative to steam engines (which apparently were liable to explode) and since (like steam engines) the heat is applied externally it is often referred to as an external combustion engine. Modern versions are more complex and advanced than the simple example described here.