It?s midsummer, the number of daylight hours is at its zenith and Britain?s fledgling solar-electricity industry is at its peak production. There is now a generous tariff paid for solar electricity exported to the grid, so putting panels up on your roof represents an excellent return on investment ? between 5 and 8 per cent, depending on how far north or south you live. No wonder money pages and finance websites are recommending home owners install these income-generating mini power stations. No wonder installers such as PV Solar are putting up 25 systems every week and have over a million pounds? worth of orders.