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Hi,

I am trying to connect Enphase inverters alongside an Alpha ESS B3 system.

The B3 has CTs around the grid and the solar production - works as expected.

The Enphase envoy is set to G98, and has CTs around production and grid.

I am wondering if the grid CT is actually needed on the Enphase Envoy?

Thanks.

vantech2022 wrote: ↑Sat Nov 19, 2022 8:42 pm Hi,

I am trying to connect Enphase inverters alongside an Alpha ESS B3 system.

The B3 has CTs around the grid and the solar production - works as expected.

The Enphase envoy is set to G98, and has CTs around production and grid.

I am wondering if the grid CT is actually needed on the Enphase Envoy?

Thanks.

I believe you still need the grid CT on the Enphase to prevent/limit grid export. G98 is essentially an absolute export limit for the sum of all grid connected devices such that 16A per phase (around 3.68kW for a single phase) cannot be exceeded.

My planned way around having two inverters connected to the grid is to ensure that the sum of the exported power from both cannot exceed the 6kW that we have G59 consent for (G59 is now G99). To do this I've made up (but not yet installed) a G100 export limit switch, that isolates the second inverter from the grid if the exported current exceeds our permitted 26A.

Thanks.

The alpha battery has G100 export limitation, set to zero export. This means that it does not export to the grid, so even if the solar inverter is at full output (G98) the battery does not export.

The question I suppose is does the Enphase inverter need to be set to zero export?

vantech2022 wrote: ↑Sat Nov 19, 2022 9:25 pm Thanks.

The alpha battery has G100 export limitation, set to zero export. This means that it does not export to the grid, so even if the solar inverter is at full output (G98) the battery does not export.

The question I suppose is does the Enphase inverter need to be set to zero export?

I hadn't realised you had already got a G100 zero export on the Alpha. In that case you don't need the CT for the Enphase, as long as you can't export more than 16A from it. There might be an issue with export from the Enphase shutting down the Alpha, though, as the Alpha CT will see the export from the Enphase and then shut itself down, I think, as it will have no way of knowing where that export is coming from.

Oldgreybeard wrote: ↑Sat Nov 19, 2022 9:34 pm

vantech2022 wrote: ↑Sat Nov 19, 2022 9:25 pm Thanks.

The alpha battery has G100 export limitation, set to zero export. This means that it does not export to the grid, so even if the solar inverter is at full output (G98) the battery does not export.

The question I suppose is does the Enphase inverter need to be set to zero export?

I hadn't realised you had already got a G100 zero export on the Alpha. In that case you don't need the CT for the Enphase, as long as you can't export more than 16A from it. There might be an issue with export from the Enphase shutting down the Alpha, though, as the Alpha CT will see the export from the Enphase and then shut itself down, I think, as it will have no way of knowing where that export is coming from.

Thanks,

The Alpha system has PV and Grid CTs so it can monitor import, export and PV generation.