This forum thread will track of the version history of the following download:
Solar panel costing.xls

I have also been investigating purchasing a solar p.v. panels to free my house from the national grid. Using my electricity bill and using information on
www.windandsun.co.uk/System_sizing_grid_connect.htm
I calculated that I could totally replace my electricity supply with 17 solar panel units each covering 8sqm. The cost is a whopping £102000 about ($204000). Ignoring interest that’s a 76 year payback period and the system only lasts 25 years.

The electricity produced by rooftop wind turbines in urban areas is so small they may do more harm to the environment than good, a report has confirmed. Energy savings figures from roof mounted urban wind turbines have been revised downwards. The 18-month study by the Carbon Trust and UK Met Office showed that installing turbines on the roofs of many homes does not generate enough green electricity to even counter the carbon emissions created by their production, installation and operation.

Does any green initiative actually stack up on paper or is simply a costly gesture?

The wind turbines mentioned in the latest ExcelCalc post were small roof mounted turbines but what about the large turbined that can be placed on top of large buildings or mountains or in the open plains as in the US and promoted recently by T. Boone Pickens and does Mr. Pickens have an interest in those companies or are his motives altruistic?

Has anyone got a break even analysis of ground source heat pump home heating?

I have not worked up a calculation but I think most of the information can be found www.essentialspark.co.uk. Please upload the calculation to the site if you manage to get round to it quinetic.

In response to brab's comment - I am picking up the impression that larger scale projects might well be feasible but when I look into home grown solutions they just don't seem to stack up which stifles you enthusiasm to do anything.

I am interested in quinetic's comment on ground source heat pumps. Even though you need provide power to the heat pump I think there is something like a 3:1 return in the form of heat.

Does your property have a water course crossing it, a stream or river. Do you own an old water mill? Water turbines/ hydroelectric turbines are the ideal method to provide reliable renewable energy on a long term basis. The available power at your proposed site is simple to calculate using this equation:

Power (watts) = Head (m) x Flow (litres/sec) x 9.81 (gravitational constant ‘g’)

A typical efficiency of water to wire is around 70%, you should therefore multiply the result by 0.7 giving the actual amount of electricity that you could expect from your proposed hydro site. Looking at your power consumption in "Solar panel costing.xls" a 3KW turbine should be adequate. It costs about £1500 so it will pay back in just over a year. Background information.