Inverter acting up at night. Hardware?

Technical Questions
#1

With the inverter of my solar system on standby at night, it typically consumes a steady 2W of power.

I’ve noticed that for the last few nights my inverter seems to be acting up, where it would occasionally cycle (~1-3 second period) between consumption (up to ~-15W) and production (up to ~15W) for long stretches. Then it’s quite again for a while. This is in the middle of the night. No sunlight, no moonlight.

Have a look at the picture from the last two nights. The green arrows point at three such periods.

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I first noticed it on the main “Now” bubble screen. where the solar bubble would constantly appear and disappear when it’s dark outside…

Looking back at the history, this started a few days ago. Was always steady all night before.

I worry that there might be something faulty. This is a Xantrex converter from 2009.

Anyone seen something similar? Anything I could test?

#2

Hey @altenbach - I believe the answer to your question is in this thread. Let me know if this wasn’t what you are referencing.

#3

Thanks for the link. While it seems that some inverters naturally seem to act this way at night, for me it’s a new issue, and I doubt that you updated the Sense firmware in the last two weeks to make this effect suddenly more visible. In the past, the inverter always displayed a rock steady 2W consumption at night.

Please note that these old Xantrex inverters do have some history and mine got retrofitted at that time with special clamps that prevent injury from the cover flying off due to capacitor failure. (I assume that they also replaced the capacitors, but I cannot tell).

I’ll just keep an eye on it and see how things develop. Performance under sunlight seems normal.