Nighttime Solar Production - Really?

#1

I get a reading of 6w on my solar production all through the night. I assume my panels are not actually producing at midnight. Suggestions on what might be going on?

Not sure if this is related but since turning on my panels, my always on reading has been drastically lower than previously. (I had Sense for about a year before adding panels and adding on the solar CTs.

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#2

My shop monitor always shows 7 or 8 watts during the night. I wonder if it is seeing a voltage feedback from the line voltage that feeds the solar panels so that the inverters sinc the proper sign wave during the daytime production.

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#3

Sorry @joelzook, I don’t think I can answer either of your questions.
Noticed it was your first post and want to welcome you to the community.

#4

Interesting, my solar always runs a negative 5W overnight. I assume it’s the power draw on the Enphase Enlighten box. What panels/inverters are you using? Wonder if some have a little battery storage for keeping monitors up overnight.

#5

I have 20 370w Jinko panels paired with Enphase IQ7+ microinverters. There’s no batteries in them as far as I’m aware.

My first thought was that I had the CTs installed wrong (because I too thought it more likely that the reading should be -5 watts overnight). But my solar production is tracking as expected.

#6

I had a situation similar to yours. When sense was first installed the solar panel inverters registered -5 to -7 watts all night when the panels were off. I assume that is the power to run them even though no solar panel power was being generated. I have 2 Solar Edge inverters. I had to move a couple wires in my main panel and in the process moved the CTs for the inverters a bit. This caused the minus numbers to go away and now they show +2-7 watts overnight when the panels are off. I’d look into how your CT are placed. You may have the same issue I ran into.

#7

solar panels don’t use power at night, but the inverters do… the electronics monitoring/looking for DC output from the panels (since they really don’t know day from night)… its usually not very much, <10w… now, with that said, my PV system shows 5~7W generated all through the night… upon investigation, I have an apartment complex to my south (in front of my array) and they have a parking lot light that stays on all night… also, looking at the Sense details, I’m actually negative on one leg of my solar and positive on the other during the night… so, my conclusion for my setup is that some of my panels are getting power from this parking lot light next door and the rest are using power as expected…

for comparison, my system is 17 sunpower 360W panels with micro inverters…

anyway, hope this helps to understand…

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#8

I think what we are seeing here is just the measurement accuracy of the Sense. It is not that precise and so when current is actually zero, it is registering a handful of watts either positive or negative.

I would not read much into it. Consider it “noise”.

Mine does the same.

Though as folks point out, I could see the inverter(s) taking a little power at all times from the grid for their electronics, so yeah, a small negative number there is totally logical.

#9

I don’t have sense on my solar panels because of my setup, but I have seen my panel monitor perk up at a full moon on occasion. It doesn’t generate more than a handful of watts, but it’s enough to wake it up. maybe you are seeing something along those lines.

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