Small scale solar pv systems of less than 4kW in capacity completed after midnight on July 31st will receive 16p/kWh rather than the current 21p/kWh rate, as part of changes to the feed in tariff scheme announced by the Department of Energy and Climate Change (DECC) earlier this year.

The Solar Trade Association maintains that solar pv systems could still generate good rates of return of just over nine per cent.

The trade body has created a new "calculator", which factors in the change in subsidy, the recent increase to the export tariff available to installations, and the government's projections for electricity prices to show how much money installations can save and generate each year.

Figures released by DECC yesterday show that more than double the capacity of solar power has been installed since April this year, compared to the same period last year, despite a cut to the feed-in tariff on April 1 2012.