Hello Martin,
I understand that you have irradiance data for sunny day, cloudy day, etc which you want to map to time of the day using a look up table. Irradiance value has a one-to-one mapping with the time of the day, so you must use a 1D Look up Table(LUT).
Irradiance_at_a_particular_time = f(time of the day)
I think one of the simple ways would be to use as many 1D LUT as the types of weather conditions and then use a switch case block to switch between the weather conditions as shown in the model below.
It may look complex, but it is simple to understand and does the job. You can create wrapper subsystems to simplify it.
You can set the Look Up Table parameters for each by changing the table data as shown below:
Hope it helps.
