Hi,
I have a strange issue with feeding to the grid when disabled.
- Multiplus-ii 230v 8000va on 481 with internal grid monitor
- 3 x MPPT 250/85 on 3.13
- Cerbo GX on 3.12 (also tried 3.13)
- 12 x Pylontech US3000C (6 x 2 in parallel)
- 3 Lynx Distributor
I have configured ESS with BatteryLife (self-consumption) and a grid set point of the default 50w. Grid feed-in is disabled for both AC and DC PV. Setup is as per the ESS and Victron with Pylontech manuals
The system has been running for a few weeks and the Active SoC has been slowly climbing due to low PV and reached 80% a few days ago.
On a previous sunny day the MP2 swapped to using the battery rather than the grid (maintaining around the set point) until it dropped back to the Active SoC and started supplying all the loads from the grid again.
Today we had a good morning on the solar (over 2.5Kw at some points) before it clouded over and PV dropped to around 100w. SoC got to 84% and loads started to be supported off the batteries rather then grid the same as it did 5 days ago… but this time the AC in was varying wildly and on occasions feeding back to the grid. Also the AC out loads were reporting as higher than they actually are.
When I physically disconnect the grid the AC load returns to what is expected, but when I turn the grid back on the AC loads go up again for no visible reason.
Grid Off
Grid On (same AC load)
Even though the AC load is varying by only a few watts +-10) the Grid In number is changing wildly from -60 to +150 and settling on a negative ’feed in’ number for seconds at a time.
The only recent changes was adding the third MPPT and the Active SoC reaching 80% (now dropped to 75% due to good solar this morning and this seems to line up with when the issue started)
Things I have tried:
- Disconnecting the new MPPT from the GX as this was the last change
- Total power down and up including battery modules
- With the MP2 powered down, putting a 3.5mm Jack in and out of the external current sensor port.
None of the above has made any difference. It feels like the AC current out isn’t working correctly and the inverter is over producing and then over correcting, but it is working fine when the grid is disconnected.
Any suggestions gratefully received.
Thanks
Graham
AC in for the last week