Effect of Solar Power on House Prices?

Does anyone have any experience of selling houses which have a full MCS certified solar PV installation? These houses have a guaranteed income stream, inflation adjusted and tax free, for up to 25 years. If you were buying a business, it would not be unusual to factor in a 5-6x earnings comparison into the price - so in the housing market, a solar installation of say 1.8Kw producing around £1,000/year in the South of England ought to add at least £5,000 to the value of a house as it will come in regardless, unlike a business where you have to continue trading.

Interestingly this is also about the current cost of such an installation.

Am beginning to believe that Eco-Housing is coming out of the terrain of the beardies and tree huggers and about to go mainstream (which is good as I am off the EcoBuild 2012 this week).