I have a question that I am not in a position to answer right now, so perhaps someone may be able to help.
My envisaged system is in a locale that to me is borderline when it comes to overvolting a 150V MPPT. Whether this is a hard threshold or not, I treat it as one.
So I have up to now, only used two 72 cell panels in series, not 3. I may standardize on 60 cell panels in future, but then it would be 3 panels in series not 4.
I want to cheat the big difference in voltage between the Vmp and the Voc, if I can.
And this is where I wonder if I can, because I know several of you have systems on the coast and can trust that you will never have frost, and can take the risk of 3 x 72 cell panels in series.
My completely baseless untested hypothesis is that I will only get freezing conditions as well as sufficient light in the early morning.
Can I get away with that extra panel in series, on North and West strings? - Things should’ve warmed up by the time they start to deliver.
(If I stick to 2 panels in series on East strings).
I have no historical data, to either support or disprove this. So I hope that a few board members can chip in with the sort of maximum voltage they see early on cold mornings.
( I don’t even know if systems record the PV voltage before the MPPT kicks in, or if the MPPT kicks in very early and avoids these higher open-circuit voltages altogether).