Convenient approximate input data for gendaylit?

radiance-general
1

I’m currently using gendaylit taking the input for the direct irrad, diffuse irrad, and dew point, from weather stations data.

However, I was wondering if there’s any simpler (yet less accurate) procedure, perhaps using some sort of approximate tables, so that given latitude, longitude, month, day, and local time, for any location in the world, you could get a rough estimation of the direct irrad, diffuse irrad, and dew point.

Do you know of any approach that could do that?

Of course I don’t mean to stop using more accurate weather stations data, just that sometimes I’d prefer to start working with a quick/rough estimation without having to search for data, and later find more accurate data if it’s available.

Thanks a lot!!

2

If you want a code, you can use PVlib in python or matlab to generate these. The steps are:

  1. generate an extraterrestrial irradiance
  2. calculate sun position
  3. use a DNI estimation model (for zenith, campbell_norman)

You could skip 1 by just making an assumption (~1366 W/m2); the key part is the zenith angle as it calculates the amount of Air Mass the light goes through and applies a beer-lambert relationship .
This is also explained in PVEducation Air Mass | PVEducation if you want the simple equations