Also a twelve year payback is not bad as this is really showing a 8% return, on something that will add value to your home, and as energy prices rise so will the return,, so if electricity charges rise by 60% in 6 years as suggested by OFGEM, then your return will be a lot more as the energy you export will rise and the generation tariff will rise by inflation and this is all tax free, the whole deal is a lot better than putting the money in the bank and getting a staggering return of 2-3%

I came across a reasonably good article on PV economics from the US which made this point ‘The Market Value and Cost of
Solar Photovoltaic Electricity Production’
Severin Borenstein
January

The cost of a 10kW PV installation in 2007 quoted in the article was $80,000, with the inverter cost $8,000 – per article “After installation, the largest cost that the owner of a solar PV system is expected to
face is for replacing the inverter. Median time-to-failure estimates for inverters range from 5-10 years, so I assume 8 years, which implies that the inverter will have to be replaced twice over the 25-year life of the panels, assumed to occur in years 8 and 16. Current
inverter cost for a 10kW system is in the range of $8000, but that is likely to decline over time. Inverter costs are assumed to decline by 2% per year in real terms, consistent with a study by Navigant consulting (2006) for National Renewable Energy Laboratory.2008″

The really interesting question however is how large wind farms and small microgeneration interact in the market – if the goal is less CO2emissions and greater fuel security, from which does society get a better return for each £ invested? – nobody appears to be looking at this issue.