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urantia avatar image
urantia asked

Intentional islanding

Although my idea of solar installation has always been off-grid, having grid, suplier installed the ESS assistant for my AC-coupling + DC-coupling system. I am not at all happy with this configuration and I am reluctant to be hooked to the grid. I understand the grid as the last resort, as if it were a generator. In other inverters such as the Sunny Island, the configuration in this sense is very intuitive, but at Victron I am reading dozens of documents, experts opinions and moralists that do not clarify the matter as I think it deserves.I would like to know which assistant or assistants can be configured to work in isolation with an ac-coupling + dc-coupling, using the grid as generator.I found a post where they recommend the following:
- AC-Coupled
PV Inverter Assistant + General Flag and Generator Start/Stop
-DC-Coupled
Virtual switch - Dedicated ignore AC InputHonestly, if I'm asking, it's basically due to my ignorance and I totally don't know how these combinations work.

All the best


ESSGeneratoranti islanding
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2 Answers
Alexandra avatar image
Alexandra answered ·

@Urantia

Virtual switch does not give the inverter a way to frequency control the AC PV inverter.

The AC ignore and the PV assistant would then work better in your case for frequency shifting.

The other way is to use the relay on a gx to open and close the contactor, then you can program or connect with the generator controls on the GX. (So can easily be manipulated). But if you have AC PV and the PV assistant when you connect to the grid, the PV will stop producing.

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urantia avatar image
urantia answered · 
Thank you very much Alexandra. I sense this conversation is going to be productive. As I understand it, in the second option, I have to configure the assistant as "pv inverter support" and activate the internal relay of the Cerbo GX to control an external contactor that connects the grid directly to the loads because if it were connected to Multiplus AC-IN, PV will stop producing. I don't understand this last assertion because the inverter was already out of production. Remember we don't have power in batteries, it's the apocalypse. In this case, I imagine my DC-Coupling system will charge the batteries once there is solar power and whole system could start again and. We could program the disconnection of the mains contactor in GX? Other question, in this configuration could we charge the batteries from the grid? It occurs to me that a third option would be to place an automatic or manual transfer switch at the output of the multiplus to supply power to the loads and when the batteries have sufficient voltage, through the charger connected to DC, then transfer switch changes to the previous position.
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Alexandra avatar image Alexandra ♦ commented ·

It is a function of the PV inverter assistant. Stated in the manual. Some people when they run their generator don't want the ac pv active.

You can use ESS assistant and also use the contactor to simulate power or grid outage conditions. The ESS manual states though it is not meant for intentional island use.

And yes if you have AC PV you also need a DC coupled mppt (even if it a small array) to recover from a black start. It is part if a good design.


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