Multiplus II - PowerAssist Loads on Input Side

Q&A and troubleshooting
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1

Hi team,
I need some assistance with the PowerAssist feature.

I have a client that want’s to add an addtional 180kW of peak loading to their site (site supply limit is 180kW).
I am trying to work out if 12 x 15kVA Multiplus II in ESS mode would achieve this.

  1. If the inverters are installed in Parallel to the grid/site loads on the “input” side of the external transfer switch, will this cause any issues with the PowerAssist function?

  2. Will the powerAssist function still function with parallel inverter units? (there is a table for peak PowerAssist output, but I assume that is per inverter).

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  1. Does the external transfer switch serve any function other than critical output and grid protection?

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2

By logic, it would be feeding any load after the CT if the transfer was closed.

Since the whole set up just injects into the system (almost like an ac pv inverter) though why would the loads be before the transfer switch and not after? Are you trying to do critical and non critical?

The transfer does what it says, transfers the load from the primary source to the loads like a ups. (So replaces the internal ones in the inverter same function.)

3

The reason of before the transfer switch is that the total peak site load (360kW) is roughly double the inverters output.

I dont want a situation where are inverters are disconnected from the grid and trying to invert 360kW

4

Hi @bridzy,

PowerAssist is a functionality embedded in the MultiPlus and Quattros and only works for loads connected on AC-OUT.

For ESS systems, there is a similar functionality called “Peak shaving”, for which you can configure system import and export current limits. By installing a grid meter, this also accounts for loads between the grid meter and the AC-IN of the Multis. Just note, that due to multiple levels of communication (Grid meter > GX device > Multis), it might not be as quick to respond to sudden load changes as the PowerAssist functionality. But a typical use case is preventing the blowing of house fuses, which it has proven to do very well.

So, in essence, my suggestion would be:

  • Build a 180kVA Victron system according to the instructions; functionality-wise it doesn’t matter if in a external transfer switch topology or the “classic” way
  • Configure it with ESS Assistant, which requires a GX device and, for the external transfer switch setup, it might also require a Ziehl relay UFR1001E
  • Add a grid meter at the grid point to make the GX device aware of the loads in between the grid meter and the AC-IN