Apparently it depends on the code cycle, system size and whether you are a PE (post #58). Also, my thesis is that voltage change vs irradiance is NOT insignificant like most people claim, and it may be overly conservative to ignore it in system design.Isn't this all irrelevant to PV system design? I know, I know; when has relevance mattered to us?
Wellll... maybe. I am a PE, but I have no idea whether there is any "industry standard method maximum voltage calculation" that allows for Voc adjustment with differences in irradiance. Frankly, it has never been worth it to me to jump down that rabbit hole, but if you have occasion to enlist the services of a PE to use that article to justify longer strings for a design, I would be interested to see his or her work.
Yeah, as is often the case, that really isnt the best NEC language there. IMO they should have said something like, "voltage shall be permitted to be calculated based on all relevant factors" or something.
PVsyst does, I'm pretty sure. I used it a few times 10 years or so ago, but it's pricey and I don't know if its results can be used as a way to reduce Voc for system design per the NEC.
