Shelly EM & solar panel measurements : constant nightly returned energy?

I’ve a 3-phase electricity setup with 2 single-phase solar installations, linked to phase 1 & phase 2 (phase 3 has no solar injection). I’m using 2 Shelly EM’s to measure the input of both solar installation (2 different phases, so I need to ensure each Shelly is getting power from the right phase).

The new solar installation is showing a nightly returned energy of about 14,5 W, which I find rather high. The old installation also shows a nightly returned energy, but limited to 3,5W. As a result, the energy dashboard in HA, is showing a constant return value each night.

Is this normal? Is there anyway to fix this?

PS: when the night is over, I see limited positive peak where the inverter is activating, showing it is (for a short moment) consuming power, which also suggests me that the inverter (Solis) is turned off at night. The old inverter (+15 year old, no datalogger) doesn’t have this behaviour.

Could it be a calibration issue on the EM device?

Is it a Shelly EM (Gen1) or a Shelly EM Gen3?

Is there anything near the clamp that could interfere? (circuit breaker) then increase the distance.

Are the cables of the clamp coiled up? then open them up and lay them in the largest possible arc.

What is displayed when the inverter is switched off completely by hand? or is the Clump simply removed from the cable (but then in the same position)?

My EM (Gen1) never show a positive power on my HM-600 or HM-300

Many thanks for the follow-up.

It’s an Gen 1 EM. I don’t think it is interference, as I tried with both clamps of the EM: 1 close to the breaker, one further away. Both have the same readings. Not sure if it a callibration issue - anyway: that is not something I can influence, I guess.

Here’s a picture that might clarify it better :

Green is the wire with incoming solar energy. Goes to the breaker, which is where the Shelly gets it power (blue). Red is solar energy going to the into my homecircuit (other location below).

I’ll check what the effect is tonight when I would if I turn off the inverter (as it is in another room, it has an extra breaker over there which I’ll turn off). Probably it will all go to zero.

Measurements of this morning, including 15/20 min of positive power usage by the new inverter (yellow/red). The old one doesn’t have this. I do find this a bit weird, the solis manual doesn’t really specify this behaviour.

I still don’t understand this?
If the inverter consumes something at night, the power value must be positive, if solar power comes in, then negative

That’s true. So there must be another explanation. I don’t think it is the street lights that can cause this, right? The line is very stable…

Confirmed, when the inverter is shutdown (via his own breaker), the power becomes 0. So it seems the inverter is passing down an constant return of 15W for no apparent reason (during the night).