Centre for Alternative Technology (CAT) have produced a Solar Calculator, accessible online at http://info.cat.org.uk/solarcalculator
which helps you get a rough estimate for costs and returns from a domestic solar PV scheme. The cost estimates we used were based on average market rates last autumn, and prices have fallen since then.For example, Tesco Renewable Energy now quote less than £15k for a 3.96 kW system.
Can you provide any evidence for your statement about lifetime of PV panels?
You will find it hard to find a panel on the market that does not guarantee at least 80% of its initial output after 20 years.I've written an article on the life expectancy of solar panels which draws on both our experience at CAT and on research in Switzerland.It's available at
Undercurrents is an award winning alternative news service producing videos of people taking inspiring actions. http://www.undercurrents.org