Erratic output from solar panel

[wklopf1]

I have a system consistion of 32 230 watt Schott solar panels which were installed in 2011. They are on Enphase M225 microinverters. Yesterday I noticed that about two weeks ago, one of the panels started producing only a fraction of the power of its neighbors. This AM I turned the system off and disconnected the panel fromthe microinverter and checked the output. It was developing 34.4 volts, open circuit, which the current was 2.4 amps. Considering that it was cloudy with occasional sprinkles, that seemed to me about what it should be producing. When I turned the system back on, I saw that just prior to my shutting it down, the panel in question was performing the same as its neighbors, but after a while, it was producing nest to nothing. I then watched the replay of the power generated over a few days. The subject panel at times was the equal of the rest at times and at other times produced less, sometines essentially zero output. Any ideas what I am looking at? A bad panel, microinverter, or something else? Any thoughts will be appreciated.

[SunEagle]

I have a system consistion of 32 230 watt Schott solar panels which were installed in 2011. They are on Enphase M225 microinverters. Yesterday I noticed that about two weeks ago, one of the panels started producing only a fraction of the power of its neighbors. This AM I turned the system off and disconnected the panel fromthe microinverter and checked the output. It was developing 34.4 volts, open circuit, which the current was 2.4 amps. Considering that it was cloudy with occasional sprinkles, that seemed to me about what it should be producing. When I turned the system back on, I saw that just prior to my shutting it down, the panel in question was performing the same as its neighbors, but after a while, it was producing nest to nothing. I then watched the replay of the power generated over a few days. The subject panel at times was the equal of the rest at times and at other times produced less, sometines essentially zero output. Any ideas what I am looking at? A bad panel, microinverter, or something else? Any thoughts will be appreciated.

It could be the micro is over heating or a wiring connection is not complete again due to heat or expansion at the connection.

Issues that come and go are hard to identify but more than likely it is a wiring issue as opposed to equipment failure.

[wklopf1]

Thanks for the input. Finding poor connections or breaks in wires presents a real challenge. It was in the 40s today, so I don't think that here should have been any over heating taking place. But I have developed a plan of attack. Thanks again.

[Ampster]

Does Enphase have any remote diagnostic capability? If the communications are stable at least one might assume it is the DC connection that is the issue. Enphase may have more details about DC current and voltage.

[wklopf1]

On the page where you can see the production by each panel, if you click on the unit in question, you get an indication of whether the microinverter is normal. This one always shows that it is normal. I'm going to make up two sets of extension cables and swap inverters between two panels, while leaving everything located where it is. This might give me an indication of whether I should be looking at the panel and its wires or the microinverter and its wires.

[SunEagle]

Thanks for the input. Finding poor connections or breaks in wires presents a real challenge. It was in the 40s today, so I don't think that here should have been any over heating taking place. But I have developed a plan of attack. Thanks again.

Well extreme cold can cause things to shrink and terminations to change.