Odd values after electrical work

Yeti · 2024-06-04T09:25:53.180Z

Screenshot_20240604-0918381080×2340 142 KB

For some reason after some electrical work for heat pump installation I am getting odd values that seem to vary based on solar production.

The image shows that as solar export increases the use decreases. This isn’t the case as the use doesn’t change. Also the max solar output isn’t quite right.

Obviously the first thing I suspected was a CT had been moved or turned the wrong way but this does not seem to be the case. When there is no solar generation the home use values seem to be pretty close to what I would expect. When the sun is out the solar production seems to be roughly correct but at times site export is greater than solar generation which isn’t possible.

I’ve checked the cts are in the same place as they were before, checked that they are properly closed and that they are plugged in to the emonpi correctly.

I’m at a bit of a loss as to why the output is a bit strange now when nothing physical seems to have changed. Am I missing something obvious?

TrystanLea · 2024-06-04T10:21:28.405Z

Hello @Yeti it might be worth unclipping the sensors and cleaning the surface of the ferrite cores and re-seating them again?

Yeti · 2024-06-04T11:22:18.630Z

Thanks Trystan. I’ll certainly give it a try.
Just odd that the solar value is affecting the usage value. The Zappi and solar inverter are confirming the emonpi isnt quite right.

TrystanLea · 2024-06-04T11:54:24.226Z

I think you may have type 2 monitoring Solar PV — OpenEnergyMonitor 0.0.1 documentation where there is one CT on solar generation and the other on grid import/export? Consumption is then calculated by summing: grid + solar.

E.g lets say solar is generating 2000W and the grid CT is reporting -1000W (export). Consumption will be 2000 - 1000 = 1000W.

If the grid CT was under-repoting by 50%, Solar generation 2000W, grid CT would report -500W, Consumption = 1500W.

If the solar CT was under-repoting by 50%, Solar generation 1000W, grid CT would report -1000W, Consumption = 0W…

TrystanLea · 2024-06-04T11:55:23.510Z

It’s worth double checking your input processing in relation to the solar PV guide linked above as well.

Yeti · 2024-06-04T12:47:31.090Z

I think this is likely the problem, especially since the issue arose after the electrician was working on the consumer unit and I didn’t change anything on the input processing. Think I need to check the CTs more carefully.

I take a look at it all again and let everyone know how I got on.

Yeti · 2024-06-11T13:09:49.074Z

I checked the solar generation CT and there was the tiniest bit of duct tape stuck on one side of one of the iron cores of the CT. That was clearly enough to upset the measurement of the solar output. Everything is now back running as it should and all figures tie in with other sources of information.

Thanks for the help.