Solar Insolation Levels
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Solar Insolation Levels

What is Solar Insolation?

Solar Insolation is the amount of electromagnetic energy (solar radiation) incident on the surface of the earth. Basically that means how much sunlight is shining down on us. By knowing the insolation levels of a particular region we can determine the size of solar collector that is required and how much energy it can produce. An area with poor insolation levels will need a larger collector than an area with high levels. 

Solar insolation levels are generally expressed in kWh/m2/day and is the amount of solar energy that strikes a square metre of the earth's surface in a single day. Btu or MJ may also be used, in which case the conversion is:  1 kWh/m2/day = 317.1 btu/ft2/day = 3.6MJ/m2/day

The raw energy conversions are: 1kWh = 3412 Btu = 3.6MJ = 859.8kcal

Insolation levels change throughout the year, lowest in winter and the highest in summer.  Close to the equator the difference throughout the year is minimal whereas at high latitudes winter can be a fraction of summer levels.   A very high summer value, as you would see in a hot desert is 7kWh/m2/day.  

Below are links to a list of insolation levels for main cities in each region.  If there is no location close to your home you can contact us and we will look up values specifically for you position.






     Middle East

     New Zealand

     South America


To learn more about solar installation requirements, including optimal direction and angle of installation, click here

Once you have chosen the data set for your location, estimate the output of your collector each year by clicking here

If you are a solar professional and would like to learn more about solar insolation, and how to find insolation levels for a specific location please apply for access to the Apricus Tech Centre. 

Founded in 2003 by Australian Mick Humphreys with a specific focus on solar thermal solutions, Apricus has since grown into a global company with distribution and support offices worldwide. 



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