Net metering config

[david81]

I'm in the process of having a grid-tied solar system installed. The electrician came by today and was kind enough to run one of the legs of the supply side tap coming from the inverters through a spare 80A donut CT. When the tap was installed on the feeders, the existing split-200 CTs were moved to a position before the tap (meter side) so they should be seeing consumption from the grid as well as excess pushed back to the grid. (Rough approximation of current setup below). I won't have panels installed until sometime next week then will have to wait on PTO from the power company before I start seeing power from the panels, so I don't have any live data yet, but I'd like to get the GEM configured ahead of time so I can hit the ground running.

How should I be setting up the channels in the GEM in order to get the proper readings from the 3 CTs in play here (2 split 200s on the supply lines from the meter before the tap and 1 donut 80 on a single leg of the supply from the solar array)? I'd also like to ensure I can feed consumption and production numbers in to Home Assistant (current publishing BIN packets to a listener in NodeRed to push to HA via MQTT)

Code: Select all

Solar Leg 1 ----Donut 80-------|
Grid Leg 1 =====Split 200======|========Main Breaker

Grid Leg 2=====Split 200=======|========Main Breaker
Solar Leg 2--------------------|

[ben]

Does your NodeRed listener calculate net metered packets and are the solar legs balanced?

Net calculations are similar to normal calculations but you have to do the same calculations with the polarized wattseconds.

Watt = (WattSecond Diff - 2 * PolWS Diff) / Second Diff;
kWh = (Wattsecond Diff - 2 * PolWSDiff) / 3600000;

- Monitor the Split-200s normally
- Enable Net for the Solar CT under Channel Option.
- If balanced, either drop the range by 1 or X2 the Solar CT value in the GEM Setup Webpage.
- Use the Net calculation.

[david81]

Thanks Ben.

The solar legs are balanced (Enphase microinverters). I think I may have figured things out while tinkering a bit. I enabled Net on the split 200 channel (my logic being that they will be seeing consumption from the grid as well as export to the grid). In my packet parser, I'm taking the absWs - polWs as my export numbers (so far 0) and my polWs as my consumption numbers. That seems to track so far, as the change in abs and pol are identical (no export). The solar leg SHOULD only flow one way, but there is a network gateway in the same box, so I'm going to enable net on that channel, as well, to try and catch the consumption of that unit.

Hopefully that makes sense and I didn't do anything too crazy.

[ben]

Thanks Ben.

The solar legs are balanced (Enphase microinverters). I think I may have figured things out while tinkering a bit. I enabled Net on the split 200 channel (my logic being that they will be seeing consumption from the grid as well as export to the grid). In my packet parser, I'm taking the absWs - polWs as my export numbers (so far 0) and my polWs as my consumption numbers. That seems to track so far, as the change in abs and pol are identical (no export). The solar leg SHOULD only flow one way, but there is a network gateway in the same box, so I'm going to enable net on that channel, as well, to try and catch the consumption of that unit.

Hopefully that makes sense and I didn't do anything too crazy.

Ahh, so the Split-200s are inline with the tap. It all sounds good. Once you start getting some numbers you'll be able to verify better.