Troubleshooting PV generation wattage on 2 240V circuits with a single CT

Hey All,
I’ve had my IotaWatt up for a couple years monitoring just usage. This week I finally got a PV system installed.

I’ve got a 10.13 kW DC system installed that is feeding into my panel on 2 separate 240V circuits. One 20A and one 30A. I’ve got all 4 wires from the 2 circuits going through a single SCT013-000 100A 50mA CT (with 2 of the wires reversed to get everything in phase my electrician brother installed this when I wasn’t around). I have a few other of these CT’s running on other 240V circuits and they work good (with 1 wire out of the pair reversed so that CT detects the full power)

After setting the CT up on the iotawatt I noticed that it was showing a ~97W constant generation at night (I’m wanting generation as positive and draw by the inverters at night as negative). I noticed that I hadn’t turned on allow negative so I turned that on and the feed looked as I expected a -97W draw by the inverters. This morning when the sun came up I saw that contrary to my expectations I saw a my generation showing up as negative power. So I turned on the reverse option on that input and my generation became positive. Tonight when then sun went down again I’m seeing the same 97W generation.

I turned off the 2 breakers and saw the readings goto 0 so it doesn’t look like it’s induced current from other wires/circuits. The 30amp circuit is drawing 56w but it’s showing up as the panels generating 56w and the 20amp is presumably drawing 42W but it’s showing as generating 42w.

So I’m wondering if anyone knows is what I’m doing actually going to work with trying to monitor both PV circuits with a single CT (based on other posts it seems like this should be possible), or if anyone has any other suggestions for troubleshooting. I do have an additional input available on my IotaWatt so I could get another CT and monitor the 2 circuits individually.

I’m hoping tomorrow to open the panel up and feed each of the 4 wires through the CT individually and try to double check that all four wires are in the correct orientation and it’s not that a couple of the wires aren’t actually reversed. But any other suggestions would be greatly appreciated.

Let’s wait for the results of those tests.

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So I opened the panel up and now have the CT so that all 4 legs are in and showing positive W when the sun is out. Once it gets dark tonight I’ll see what happens :slight_smile:

Hopefully you are saying that you checked each conductor individually and oriented the way it goes through in the bundle.

Yes I got each conductor one at a time and got the flow going positive and then bundled all 4 in the associated positive direction into the one CT clamp.

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Ok so I think that has basically cleared up my issues. I’m not seeing the draw from the inverters that I would expect. Now that the sun is down I’m seeing a generation of 2-6 w, I kinda would expect it to be a draw but the amount is so small I’m not sure it’s worth worrying about.

I’ve seen this before. It’s such a low power that 2W barely registers. Whats important is that the real daily generation in kWh reasonably matches what your inverters report.

Yah it’s looking good now.