Nekit, or others,
Sorry to be so long getting back to this, but...
Kitstrings 400VAC is my target max Volts which should be about 520 VDC going into the inverter.
If your target is 520VDC, wouldn't the RMS phase volts/ph be 214 VAC; VL =~371. With a resistance of 20.4 ohms, I would have expected the phase current to be just over 10A, or about 6.7 kW assuming it is balanced (which I think it is now).
Alternatively, if as you say the most the generator has put out is 310 VDC, wouldn't the Vph =~127; VL = 221; Ip = ~6A, or roughly 2.5 kW?
Please understand, I'm not trying to be smart @#SS, just would like to understand it if I'm off-base. Perhaps the resistance changes as they heat up, like say a light filament, or perhaps the 15A was measured prior to your reconfiguration?
One more question, I assume you parallel one pair to just hit somewhere near the desired risitance with the individual elements that you had, but logically the pair is not loaded the same as the third element in each group. Just curious how close to capacity of the individaul elements it put you?