I am going for a 4kw system this summer. Tesco are offering a 20% off deal and have quoted me the best price out of the eight company's I approached. They all however, said the same thing, that the present tariff for domestic systems is likely to change in the next tax year to be less favorable. At the moment the deal is for 41.3p/Kwhr for every unit produced plus 3p/Kwh exported surplus, and yes, yes, yes tax free. They are also offering club card points. Hmmmmmm. Tesco.