10.2v input from panels showing on MNGP at night / resting

[Muskoka]

This has been going on for a while, finally getting around to asking a question. The issue is pretty much in the title. Why is the controller, Classic Lite, showing 10.2v incoming at night, while at rest?

Also, and more concerning, if I switch off the breakers from the panels the input voltage starts to rise, and keeps going on the MNGP display. Once it got to 20v I switched the breakers back on, didn't want it climbing any higher.

What is causing this, there's zero ambient light outside,  besides that would have nothing to do with the voltage rising when the panel brekaers are off.

Should add, there is 0.2 amps in the lines coming from the panels when the breakers are on, 1.0 amp when the breakers are off, measured with my clamp on meter. Where's that current coming from, it's pitch black out, can't see anything, total cloud cover, no moon.

[Wizbandit]

The input to the Classic has capacitors. There is a pre-charge kept on them of about 2/3rds of the battery voltage.  Totally discharged capacitors act like a dead short if you turn on a breaker and this sometimes causes the breaker to trip.  So we keep a slight charge on them, it also is healthy to keep them slightly charged, helps them last longer.

[Muskoka]

Thank you for the explanation.

Another question, why 10v on the display, my system is 24v. Batteries are currently 26.2v. Are the capacitors getting weak maybe?

[boB]

The input voltage at night is ballpark, 1/2 to 2/3 of the battery voltage.

The voltage can be lowered by the leakage of the PV array still connected to the Classic but in the dark so not contributing any voltage on its own.