An efficient electricity supply
One other thing to bear in mind is that when you buy electricity from a supplier, you are paying for two thirds more electricity than you will actually get!. This is due to the generation of electricity using coal, gas, and nuclear power stations being in-efficient and the power loss caused by sending electricity over long power lines, though sub stations and so on.
By producing your own electricity with a Photovoltaic system, it is not only totally clean, your electricity generating system will be about 97 - 98% efficient. You will know that this clean efficient electricity you are producing is not just wasting your money on the in-efficient generation methods of power stations.