I just installed 2 PV panels and a Goodwe GW-700-XS-11 inverter.
Yesterday at the end of the day, switched it on for the first time (not much sunshine anymore), the system supplied around 75W, which seemed sensible. When it became darker, the produced power dropped to approx 20W, but during the night it remained around 20W (varying slightly, so no static data).
20W in nearly dark condition seems unlikely. There is a street lantern at approx. 15m, but assuming the street lantern has a 50W lamp, it will not generate 20W in 2 PV panels considering the light losses and PV efficiency
Since this inverter is transformerless, I can imagine (due to a defect) some voltage appears at the DC terminals causing the inverter to stay 'on', however I would not expect any measured current: (current, if any) would flow in the opposite direction in such a case (this depends of course on the current sense circuit and calculations).
Tonight I will hook up some multimeters at the PV wires to see what's really happening, but I was just wondering if anyone has experienced something similar ?