Insolation

Insolation is the amount of incoming solar radiation. Typically, this value is about 1000 watts/m² when the sun is at its peak in the day. The weather, time of day, time of year, altitude and location all play a role in how much insolation is available to a particular area. For a very detailed explanation of solar insolation, please view the PVEDUCATION.ORG web site.

The amount of heat a solar collector can produce in a day depends on the insolation. Insolation can be found online through maps and charts based on location. it varies from the time of year, with typically less in the winter, more in the summer. When sizing a collector for a heating application, insolation will need to be taken into account to figure out how much heat can be obtained per day.

The measurement of insolation is given in the form of power per unit of area, typically in units of watts/m². For the amount of energy gained over a period of time, it can be reported in kw-hr/m².

Typically, the amount of energy measured over time is more useful as it often factors in average weather for a particular location. One way to find out how much insolation that your area receives is by using a solar calculator which estimates average insolation based on data obtained over the years for a particular location.

*Note: For the calculator above, they usually have a way to get raw insolation data, which is in the form of kw-hr/m². However, the button appears to be broken so in order to get this value correctly, enter the panel efficiency as 1 (for 100%) and the panel size as 1 for 1 m² and number of panels as 1. When you submit, the calculator will give you the average daily energy by month in kw-hr/day per 1 m² worth of area.