Solar Photovoltaic panels or solar PV panels work to produce electricity by converting energy from the Sun. In general the systems installed to generate the electricity are simple and have very few technical elements.
Solar cells are made out of a very thin layer of semiconducting material, usually silicon, between a sheet of glass and a certain polymer. Once sunlight hits the cells, electrons are excited within the semiconductor, and DC current can flow.
Solar panels are roughly 1 to 2 square metres in size, and produce about 200 Watts each. If you know your electrical needs, then it will give you an idea of how many panels you will need to take a chunk off your standard electricity take.
There are many variables which will affect how much electricity your are able to produce, including the tilt of your roof, the orientation (south is the most desirable), whether there are any obstructions, and of course, where you live in the county. Southern parts of the country experience more sun than the north, although this does not affect electricity generation too much.
There are tools online, where you can input the amount of electricity your panels produce, to calculate how long before you see a return on your investment. In general the investment is at a maximum £15,000, with a rough associated payback time of 25 years.