OpenEnergyMonitor Community

Issue with Solar setup - negative reading

Hi there, first time user and to the forum too.

My Solar Bundle came yesterday and have installed it following the instructions. It all seemed fine last night and via the App it was showing the electricity being used, no solar as it was dark.

But today, it is just showing a big negative in the power use section. It’s sunny so the solar panels are generating a lot, but I expected to see power used, solar import, export that kind of thing.

Have I missed something in the setup?
Any help would be much appreciated.

I’ve attached a photo to show what I am seeing.


Welcome, Greg to OEM (and to the forum :smiley: ).

I’m not sure I believe that. I think you need to look carefully at your wiring to make sure the c.t’s are where they should be, then look at the Inputs page of emonCMS, and check that the two c.t’s powers and the voltage are reading what you expect. CT2 should always show the PV generation, a positive value which should agree (within a few percent) with what your inverter tells you. If you have a Type 1 installation, CT1 will be measuring your house use only, so that should also always be positive. However, if you’ve got the more usual Type 2 set-up, CT1 should read your house consumption as a positive value over-night when the PV is inactive, but when generation exceeds your daytime use, it should read negative, and your Utility company’s meter should be showing a steady red LED, and possibly displaying “RED” (Reverse Energy Detected) - or something meaning that.

Did you choose the correct “Type 1” or "Type " on the “Configure Device” page, and save it?

Thanks for the reply. Just a query, to start with you mentioned that ct2 should always show the pv generation, but then later you say ct2 should read the house consumption?

Mine is a type 2 setup and I chose the correct configuration as per the instructions.

Now for example it shows 335w use, 0w solar as it’s night obviously, so seems to be correct. The minus figure in my screenshot does tally with what you have said about it, so maybe it is all correct?

Well spotted - digitus erronous.

should of course read “CT2 CT1 should read your house consumption as a positive value over-night when the PV is inactive…”

Believe it or not, I don’t have PV - and I’m only using my emonPi as a test bed for the next issue of the software!

It’s hard to know what you should be reading, because only you know (or have a feel for) what you could be generating and what you could be using.

Thanks Robert, looking at it again this morning I think I had the ct clamp on the solar side round the wrong way, so turned it round and now the use, importing and solar figures look a lot more accurate. As per photo.