Two ESS sharing same DC bus (battery/MPPT converter)?

DIY
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Hello,

I’m a huge fan of Victron system.

I would like to install an ESS (battery + solar panels) for a building with two apartments. Each apartment has its own electricity meter. I would like to share batteries/PV but keeping grid separated.

I would like to know if Victron supports having two independent ESS setups (each consisting of a MultiPlus inverter and an Energy Meter) connected to the same DC bus (shared batteries and MPPT solar charger).

If this is possible: how should the BMS and Cerbo GX (or other GX device) be connected in this configuration?

Screenshot from 2025-06-01 15-06-07
Screenshot from 2025-06-01 15-06-071080×752 38.6 KB

Thank you in advance for your help!

2

Hi, simple answer, its not supported

You cant have two GX devices control and share one battery or mppt

2 grid meters on one GX is possible, but only one can be grid meter

Maybe split phase is an option? Or some control with node red

3

Imagine an ESS setup with:

  • A MultiPlus inverter/charger
  • Pylontech batteries connected to the Cerbo GX via CAN bus
  • An MPPT solar charge controller (also connected to the Cerbo GX)
  • The battery at 100% State of Charge (SoC)
  • Excess DC solar energy being injected to the grid via the MultiPlus.

Now, imagine an external consumer draws 20A directly from the battery.

How will the ESS react when it sees the BMS reporting that the battery is discharging at 20A (an unexpected load from the ESS’s perspective), instead of reporting 0A? Will it compensate by charging the battery at 20A?

If I could, I would test this on my ESS but I don’t (yet) something to act as dummy load to test this.

Thanks for sharing your of experiences.

François

4

I use 3 ESS on the same phase.

I think to get this to work, you will need to replace the Victron MPPT with an AC inverter and use the internal chargers to charge the battery. If you dont want them to charge or discharge, then set the charge current to 0 when the battery is full.

You may need to series-connect 2 shunts from the battery. One will be used for inverter 1 to see the load of the inverter 2, and the inverter will need the second shunt to know the estimated SOC.

There will be so many quirky things you will have to do.

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5

You could use a shunt for the unexpected load and configure it as: has dc loads in remote console in GX

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