Nanosolar

At last it looks like the cost (and hopefully this equates to the energy cost of manufacture) is coming down. Nanosolar are quoting $0.99/Watt. With the exchange rate that equates to about 50pence/Watt.

If we assume that electricity costs 7 pence/kWhr then this means we need to generate 7kWhr before we break even.

Lets assume we get 5 hours of sunshine a day and so that means 5 Whr/day and so 200 days to generate 1 kWhr.

That means 1400 days to breakeven. That's just under 4 years, not so bad.