I had a running system in FL with EmonPi for my base unit and a EmonTX shield on my solar panels for 6+ years.
Since I’ve relocated to OR and setup everything again and then updated the system with two more EmonTX shields I’m getting odd readings.
Here is what I’m running into and can’t figure out.
My mains coming into the home is reading correctly (CT’s on both legs and they read a positive reading in the feeds) tested by putting loads on both legs and they seem to be correctly reading the wattage.
My solar panels are 120v coming off the inverters and I have them reporting correctly as a negative feed. That all does fine.
My inverter feeds into the panel box through a dedicated 20amp breaker.
When I am making solar power it doesn’t reduce the house power input wattage reading (this worked fine in FL).
The wattage should drop when it’s making power and take it off the feed before it goes into the input calcs.
I’ve checked all my CT polarities, have the solar set as negative input only and been through all I can think of but hopefully someone has an idea on what I messed up on???
The obvious point - where are the “incomer” c.t’s in relation to where the solar feed connects?
You are reading the raw input power - before any calculations are done on it? If the PV feed is on the downstream side, the incoming power should automatically reduce, or even go negative, when there is a P.V. contribution. But if it is upstream, the c.t’s won’t see it. That’s the only explanation that I can think of.
Quite so - IF you’re actually measuring what you think you’re measuring.
You might have been looking in the wrong place.
I’ve just realised - you’re referring to American states. Not all of us live there.
My mains are on the disconnect panel (400) amp service suppling the home and the solar is on the other side of the property in a small field. That gets fed back to the sub panel (200) amp service breaker box.
I’m going to check the mains again today and see if something has cracked or come loose with one of the ct’s but I have no idea how it could change polarity on one side only.
It’s a head scratcher for sure.
Have you identified where that connects in the main panel?
So it looks as if we come back to this:
That tells me you’re looking after any processing on the Inputs page of emonCMS. Go back there and check the raw values at the top of the process list for each leg of the supply, then check that the process steps are correct for your new installation - especially that you haven’t included (added or subtracted) the PV contribution before sending it to the Feed.
(If the PV is negative, and you subtract it in the processing, you’re actually adding it to the Feed. But the incoming power has reduced by that amount because part of the demand is being met by the PV, so the number reaching the Feed remains the same.)
Failing that, one I didn’t think of last night: have you got, or a previous owner left behind, an energy diverter of some sort that is swallowing the (excess) PV?
Another point I missed last night:
Our convention is IMPORT is positive, EXPORT is negative. The P.V. generated should actually be a positive value as your house consumption is Grid (+ve on import) + P.V. (+ve on generation).
curious since it a new location. does it have two meters. one for house consumption one for solar production. since the meter we use in N.A only go forward and not backwards ( unlike the old analog type). they are branch before each meter if you want to see both you have to connect your CT before it branches off to each meter
I do have two meters on the property but the shop is on one and the second supplies the house and solar panels. I’ve got the shop on its own Emontx that sends a signal to the base unit.