Yesterday I disabled AFCI, changed the grid code from Rule 21 to IEEE and modified the FreqHighDerate: Point=60.05Hz and Slope=100%. Results below, problem persists. I found in the debug2 field what I suspect is the derated power, since it's normally 11400 (nominal power of the inverter) and it drops along with Ppv and the DeratingMode. It's the grey series in the chart above.
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> In the graphs the dropouts don't seem to be happening in the morning- I wonder if this could be temperature related.
I plotted inverter temp below. The problem seems to get worse after around 2:00pm even as the temps return to morning levels, E.g at 5:27 it derates even though temp is just 42.8c, same as it was before 10AM. I would expect to see DeratingMode 5 or 6 (Tboost, Tinv) if temp were the problem but I don't. Although my PV modules are partially shaded at this time of day so that could be it too.
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Today I will try the following:
* Disconnect battery completely
* Measure Fac with multimeter. Morning and afternoon.
If time allows I will also Install SolarAssistant in hopes that it can monitor Fac more precisely. What if I disable Frequency Watt completely? Seems like it would violate UL 1541? But if just for a day it could at least lead to a clear diagnosis.