In addition to the Feed-in Tariff you get an additional payment for any surplus energy exported into the national grid (at the time of writing this Dec, 2011 this is 3.1p per kWhr).
The Export Tariff is the name given to a pre agreed bonus payment of surplus electricity your system exports to the electricity grid. When this payment is agreed, you are effectively selling that electricity to that energy supply company, for them to do what they wish with it. This export tariff is agreed by public utility companies of your choice such as British gas or energy first.
How much is the export tariff?
For the year 1st of april 2011 the export tariff rate is 3.1 pence p/kWh. It is index-linked to the retail price index.
You are entitled to use this export tariff rate or opt out of it and try and agree direct rate with an energy supplier. Each year you can take the floor price or opt out.
How does it work?
In a nutshell solar panel installations create energy through Photovoltaics, this energy will be used in the home, with a percentage exported to the national grid (what is the national grid?). Utility companies will pre agree a rate with you usually in the region of 3.125p per kWhr (what is a kWh?) at which any unused or surplus energy created will be exported. You will quite simply receive the amount of exported energy in kWhr x the export tariff rate for the year, either at the floor rate or the personal agreed level with a energy company.