Thoughts on LG 320 watt panels with enphase 250 micros?

[J.P.M.]

Well, but these would be comparable between systems, no? So on an absolute basis perhaps not reliable, but comparatively, fine...

For a lot of reasons, I don't agree. One example: Often, but not always, T.O.U. rates can result in a system that produces more revenue to offset a bill than the same system working against a tiered rate, making the system less cost effective due to oversizing.

Bottom line: PVWatts and in general, NREL POCO rates that I've seen, including those attributed to other POCOs besides mine are unreliable. Use them at your own risk.