Solar Insolation Maps
How Sunshine is Measured
Solar energy is measured in units of Solar Insolation. Technically, these insolation units are described as kWh/m2 per day.
By looking at solar insolation maps, you can determine how many hours of usable sunshine you get on a daily basis. This can help with figuring out how much energy your solar panels will make.
And knowing how much energy your panels will make helps in determining the payback time of your solar energy system.
Click here for a larger view.
With the larger view, you can read off the map the hours of solar insolation for your state. It's important to note here that for solar electric panels (photovoltaics) the air temperature is not as important as the hours of sunshine. In fact, photovoltaics work better at cooler temperatures.
If you're interested in solar payback time, you can also check our solar calculator. This walks you through the process of deciding what size system to get, and how it will work where you live.