The question is:
Why do I have this error shown in the debug area?
I think it comes from the code marked yellow.
Variable "PVPowerRange_Initial" is used before without any error (marked green)!
Thank you all in advance and sorry for the stupid question!
And please: Don't tell me details about the code in general! I am sure, it can be done much more smarter, but this is not what I am asking for.