For using a 100/20 MPPT charger does the Vbat +1 mean theoretical system voltage or actual battery voltage?
ex. 24 volt system +1 =25v,
or ex. targeted charge of 23.5+1=24.5v
My panels Min PV volatage at Max temperature (70c) ends up at 24.7v when running parallel panels with characteristics of 250w, 30.76vmpp,8.21Impp, 37.49Voc, 8.71Isc,-0.35Vtemp, 0.05Itemp.
It is the Voltage above actual battery Voltage.
How many panels have you got? If you have an even number of them, then you can connect two of them is series strings to make double the Voltage and still be safely under 100V.
Higher PV Voltage means that the MPPT will wake up earlier in the morning and cope with clouds a little bit better.
Here is a good article to read and within that article is a link to a handy Excel spreadsheet calculator.
