Solar Power is energy from the Sun where heat from the Sun is used to heat water in glass panels on your roof.This means you don't need to use so much gas or electricity to heat your water at home.

Water is pumped through pipes in the panel.
The pipes are painted black, so they get hot when the Sun shines on them.

This helps out your central heating system, and cuts your fuel bills. However, in the UK you must remember to drain the water out to stop the panels freezing in the winter.

Solar heating is worthwhile in places like California and Australia, where you get lots of sunshine.

Mind you, as technology improves it'll become worthwhile in the UK - see www.zeneagasolar.co.uk who claim their system can handle all your domestic water heating in the summer.
Their site has a good animation of their 'drain-back' system which avoids problems with freezing in cold conditions.