I am working on a model and must calculate the total solar radiation in W/m² on an inclined plane.

I need a function to calculate this value given longitude, latitude, date, time, tilt angle, and azimuth. The funtion can assume a clear sky.

  1. Can someone direct me to an example where the above is calculated? All the resources I found so far do not provide an example of a complete calculation from start to finish.

  2. Would it be simpler to calculate from first principles or would interpolating from an existing database be the way to go?

  • $\begingroup$ I don't quite understand what you require. Do you need the derivation of the function to calculate irradiance for any point on earth, or just the data for it? $\endgroup$
    – noah
    Commented Apr 24, 2022 at 11:09
  • $\begingroup$ @noah I was looking for the derivation, but in some cases with a complex function like this it might be easier to interpolate from existing data. So if the latter option is easier, I'd like to be pointed to some resources I can use. But the actual derivation is what I am originally after. $\endgroup$ Commented Apr 25, 2022 at 12:25
  • $\begingroup$ The irradiance at the surface is a very complex function if you want to have accurate data, so if what you need is to have a good approximation of the real irradiance, you'll have to use measurement data as your base anyway. If this is just an exercise to calculate it in a simplified way, then measurement data is not really the way to go, and you could start from first principles (which might be way off in some places). I assume you need the former, ist that right? $\endgroup$
    – noah
    Commented Apr 25, 2022 at 12:30
  • $\begingroup$ @noah I have some texbooks showing how to calculate the AST and sunset/sunrise times but there is a gap between those calculations and how to determine the total (direct and diffuse) radiation on an inclined plane. If you could direct me to a resource it would be much aopreciated. $\endgroup$ Commented Apr 26, 2022 at 9:23


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Browse other questions tagged or ask your own question.