Electric company Southern California Edison has these requirements for connecting to grid in a zero backfeed configuration. How can this be achieved with my Victron ESS system with UL1741 certified Multiplus II or Quattro (even if it requires additional hardware between the multiplua inverters and the grid)?
“…These requirements include certification for UL 1741 and UL 1741 SB as well as an attestation for Smart Inverter Phase 2 Communication requirements as established in Resolution E-5000 and as modified in Resolution E-5036. Details on these requirements are provided in SCE’s [Instructions Sheet] or visit the [CEC website].”
Some Victron units are certified under “UL 1741” but not “UL 1741 SB” (supplement B). So enabling Victron’s ESS Assistant (grid interactive functionality) is not allowed by most (all?) grid operators in the US. This is true even if you don’t intend to export.
You can still connect the units to the grid without ESS Assistant installed, which would not require an interconnection agreement. In this mode, the inverters aren’t operating “in parallel” with the grid.
I’ll also add that with ESS Assistant, it won’t be possible to guarantee zero backfeed. There is a short delay between when a large load turns “off”, and how fast the Multiplus/Quattro can react.
There’s often some language in the regional grid operator’s rules about installing 32R (backfeed prevention) relays for non-export parallel generators. Though good luck finding someone in the utility’s interconnection department who understands those rules…
Victron recently confirmed they have no plans to add the relevant grid codes to the firmware either.