A fair-sized, south-facing solar installation might put out 2kW at lunchtime on a sunny summer's day. This translates into about 1,600kWh of electricity per year – just under half the electricity an average family needs.

If the installation cost between £11,000 and £12,000, the owner might expect to recoup the cost in about 13 years.

The benefit comes in three ways:-

1. The Feed In Tariff paid by your supplier for every unit you generate - this might be about £685
2. The premium for units you export to the national grid - if you export half your electricity this might be about £25
3. The saving from not have to buy so much electricity from your supplier - this might be about £105

So the total benefit per year is about £789. The life of the system is expected to be 25 years.  After you have paid off the installation cost, you might expect an overall profit of about £8,720

These figures are based on Government estimations and are for illustration only. They are not guaranteed and should not be relied upon. Actual yields depend on weather, shading and system efficiency.