Hi All

I noticed my PV panels seem to generate voltage at night - its very small about 3.6 - 9v.

Is this the little bit of light the panels are managing to "catch" at night or is this capacitance left in the panels after the days light. i would be interested to find out more about this.

Many thanks

11 minutes ago, jasonvanwyk said:

Hi All

I noticed my PV panels seem to generate voltage at night - its very small about 3.6 - 9v.

Is this the little bit of light the panels are managing to "catch" at night or is this capacitance left in the panels after the days light. i would be interested to find out more about this.

Many thanks

Its the moonlight!

Technically still solar, just very very diffused.

12 minutes ago, PJJ said:

Its the moonlight!

Technically still solar, just very very diffused.

I should be able to run an LED or two with that😁

9 hours ago, PJJ said:

Its the moonlight!

I actually don't think so. I think it's leakage from the battery or higher voltage bus back to the input, or a zero offset with the measurement.

Moonlight is so very many orders of magnitude less bright than sunlight that it really can't even light an LED off a set of panels.

7 hours ago, Coulomb said:

I actually don't think so. I think it's leakage from the battery or higher voltage bus back to the input, or a zero offset with the measurement.

Moonlight is so very many orders of magnitude less bright than sunlight that it really can't even light an LED off a set of panels.

thanks coulomb, I was wondering about the moonlight , because there's voltage even when there's no moonlight.

7 hours ago, Coulomb said:

I actually don't think so. I think it's leakage from the battery or higher voltage bus back to the input, or a zero offset with the measurement.

Moonlight is so very many orders of magnitude less bright than sunlight that it really can't even light an LED off a set of panels.

yeah I think you are right, with 5x 330W panels in series the best moonlight voltage I could find was 1.1V

The average being around 0.2-0.5V

8 hours ago, Coulomb said:

I actually don't think so. I think it's leakage from the battery or higher voltage bus back to the input, or a zero offset with the measurement.

Is this a problem? or nothing to worry about?

4 hours ago, jasonvanwyk said:

Is this a problem?

I don't think so.

57 minutes ago, Coulomb said:

I don't think so.

ok thanks - will just keep an eye on it👍

11 hours ago, jasonvanwyk said:

Is this a problem? or nothing to worry about?

It's perfectly normal. Some MPPT's have circuits that prevent this, some don't. If you disconnnect your panels from the MPPT at night you could even read a few millivolt coming from them.

im getting 37 volt at night got 9 panels 375wat connected in series, need help how to sort this issue, system info:

4* UF5000 Pylontech

1* Sun Deye 8kva

DC breaker 63am

tanks for advice

That seems normal. What is the issue?

23 minutes ago, ishtiaq said:

im getting 37 volt at night got 9 panels 375wat connected in series, need help how to sort this issue, system info:

4* UF5000 Pylontech

1* Sun Deye 8kva

DC breaker 63am

tanks for advice

That seems normal. What is the issue?

On 2019/04/16 at 3:41 AM, Coulomb said:

I actually don't think so. I think it's leakage from the battery or higher voltage bus back to the input, or a zero offset with the measurement.

Moonlight is so very many orders of magnitude less bright than sunlight that it really can't even light an LED off a set of panels.

hello

how to sort out leakage from battery, is this could happed with lithium batteries as well, kindly advice

49 minutes ago, ishtiaq said:

hello

how to sort out leakage from battery, is this could happed with lithium batteries as well, kindly advice

There is no bleeding of the battery into the array.

The panels have a open circuit voltage, but the MPPT just brings down the voltage for readiness checks.

There are no cause for concerns at the voltages you mentioned.

Edited May 26, 20251 yr by Pho3niX90

Midnight getting 37 volt on the panels CB is this okay ??

2 hours ago, ishtiaq said:

Midnight getting 37 volt on the panels CB is this okay ??

It seems OK. As soon as the panels try to provide amps this volts would just collapse to close to nothing.

Hi,

I seem to be having a similar issue except that my PV1 string is now showing (spiking to) around 220v when connected to the grid and 120v when disconnected from the grid i.e. powered only by the backup battery supply. It has started throwing F23 faults (from around 11pm last night) so for me this is definitely an immediate cause for concern.

Setup is as follows:

• 8kw Deye Inverter

• 2 x 5kw Hubble AM5

• 12 x 545w CS panels

• Smart Load setup using CT i.e. all non-essential devices are able to receive PV power when excess is available.

The data seems to indicate it has been steadily increasing over time although I am only able to go back 6 months at most. PV2 is more or less stable however PV1 is now spiking erratically. Any ideas as to what might be causing this or how it can be resolved would be greatly appreciated.

9 hours ago, Deen said:

Hi,

I seem to be having a similar issue except that my PV1 string is now showing (spiking to) around 220v when connected to the grid and 120v when disconnected from the grid i.e. powered only by the backup battery supply. It has started throwing F23 faults (from around 11pm last night) so for me this is definitely an immediate cause for concern.

Setup is as follows:

• 8kw Deye Inverter

• 2 x 5kw Hubble AM5

• 12 x 545w CS panels

• Smart Load setup using CT i.e. all non-essential devices are able to receive PV power when excess is available.

The data seems to indicate it has been steadily increasing over time although I am only able to go back 6 months at most. PV2 is more or less stable however PV1 is now spiking erratically. Any ideas as to what might be causing this or how it can be resolved would be greatly appreciated.

My guess here would be that there is a ground leak. You will need to test for this, or get a sparky to test.

On 2025/05/28 at 4:40 PM, Pho3niX90 said:

My guess here would be that there is a ground leak.

That's my guess also.