planning – Estimating the cost of solar panels and return time? – GWC Mag

If your want to calculate your own Insolation figures then I would highly recommend having a look at the gaisma website, which provides sunrise, sunset, dusk and dawn times for thousands of locations all over the world.

For our purposes though, it also provides details of average Insolation (kWh/m²/day), along with Clearness, Temperature, Wind speed, Precipitation and Wet days.

For my own location, in Oxford, UK, it provides the following information:

Details of your own location, and prospective PV solar system should allow you to estimate the kWh generated by the system over an average year.