We fitted solar hot water to the lodges (DIY, evacuated tubes) and over a measured 18 months looks like we have halved the electricity bills for these. Have fitted (spring 2010) solar HW on the cottage - harder job as the roof is higher and is slate. It works really well as south facing. Then comes the house - higher still and old slate...
We have installed a 11Kw Gaia wind turbine - powers the whole farm - all the properties, and solar PV 4KWp on the new lodge.
We run a farm for wildlife and have 3 self-catering eco-lodges and a cottage that pays our way for this. We are very passionate about shrinking our footprint and about improving the land for local habitat and wildlife. We have a small area of SSSI on the farm. We are nearly finished building a new eco lodge by converting an old cowshed. www.wheatlandfarm.co.uk
DIY solar hot water is easy if you can do plumbing and hugely worthwhile. Costs about £1500 per install if DIY.
June the 220litre HW tank was at 65 degrees C and only because I set it not to get hotter than that.