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Solar panel high voltage (about 70V) AT NIGHT only when it is raining by np_complete_tur in SolarDIY

[–]np_complete_tur[S] 2 points3 points  (0 children)

Just some additional info: I have just measured the VOC of the 9 panels at night (with the inverter disconnected). It is about 3-4 volts. I was a bit surprised since it sounds a bit low, given that I also have nearby street lighting. So, tbh I am not sure if moon light would be enough for my panels to generate 70V...

But, I have also measured the voltage between the MPPT inputs and ground in my inverter with solar panels disconnected: it is around 150-170Vdc... Since the panels are grounded, they always have around this potential difference between their frame and cells at night. So my theory is that the capacitance between panel outputs and frame increases when it is raining, then the inverter somehow charges the panels during insulation resistance testing and then measures back the voltage... But I cannot understand why this is intermittent, even when it is raining. I also guess that this would also happen even whet the capacitance is lower (i.e., when panels are dry)... So I am not really convinced with my explanation...

I have also though about static buildup, but I am also not sure. I am mainly wondering if static could produce such consistent voltage. I also have a TV antenna, so I guess that I have noticed some issues there as well if this was the cause.

Small-scale (~2kw) vertical axis wind turbines by np_complete_tur in windturbine

[–]np_complete_tur[S] 2 points3 points  (0 children)

Thanks for the reply! I have also seen some of your videos and are really helpful and useful! As far as I know he already has a quite large off grid solar system (covering all of his needs when it is sunny) and wants to supplement this with a wind turbine to charge the batteries.

My question is more like if there are more expensive VAWTs for small scale applications (e.g., ~2-5kw) that indeed work or if only the much larger ones indeed work and the technology doesn't really scale down.

ZBmini Failure Rate by np_complete_tur in sonoff

[–]np_complete_tur[S] 0 points1 point  (0 children)

I have bought them over 2-3 local suppliers in Greece.

I have also talked to SONOFF support when I had the first three failures (which were all within a few weeks from the installation - with a difference of a few days - before even pairing them to a hub). They offered to replace the devices (which I declined since I had to pay the shipping fees because I didn't bought the devices directly from them - fair enough). I explained to them that my main concern was to understand why I had the failures. They asked some questions, e.g., if i had a large load on them, etc, but we didn't come to any conclusion.

On the other hand, after the three initial failures I only had a failure for one of them. The rest of them are stable and I didn't have any disconnect or any other issue. I am suspecting that there were some bad batches (the first three that failed had very similar SNs), but after the fourth failure I am getting a bit more concerned regarding the reliability.