Payback http://www.bwea.com/pdf/small/mid-wales-microwind.pdf

Payback
Calculated using an windspeed of 5.5ms-1, giving an average output of 200W, for an annual yield of
1,753kWh.
Year 1 2 3 4 5 6 7 8 9
p/kWh 8.00 8.80 9.68 10.65 11.72 12.89 14.18 15.60 17.16
Value/£ 140.24 154.26 169.69 186.69 205.45 225.96 248.58 273.47 300.81
Total/£ 140.24 294.50 464.19 650.88 856.33 1082.29 1330.87 1604.34 1905.15
For a baseline scenario the payback for the Swift turbine is something less than 8 years. Against an
equivalent cash investment at a bank rate of 5% the payback timescale increases to 11 years.