But that's not true - V_OC for PV modules is nearly always spec'd at STC or NOCT, which is clearly stated on module datasheets along with the temperature coefficient of that voltage.
E.g. choosing a random Jinko datasheet: https://jinkosolarcdn.shwebspace.com/uploads/JKM600-625N-66H...
V_OC is specified at both STC and NOTC, and the datasheet clearly states which environmental conditions accounted for in those test conditions.
It doesn't matter if it's true. And those spec sheets aren't what you'll find on amazon products. I looked at them, didn't see any mention of temperature. Also, stupid things use XT60 connectors. Not remotely appropriate for 150v DC.