question

mose avatar image

ESS not balancing grid setpoint on load limit

I recently installed a three phase setup with three MultiPlus-II 48/3000/35 (fw 459) with four Pylontech US3000 battery modules.

Everything works. During normal loads ESS balances the grid setpoint and optimizes for self-consumption just fine. Now I discovered an unexpected behaviour regarding what happens when one of the Multis reaches it's load limit during grid connected inverter mode while the other two are not doing much at all.

What I expected:
When one Multi reaches it's load limit additional power is taken from the grid. ESS balances to the configured grid setpoint as the other two are able to provide additional energy.

What happens:
One Multi reaches it's load limit at 3000VA. Additional power is taken from the grid. The other two Multis are only providing their (very small) loads. Power is taken from the grid without balancing to the grid setpoint - energy is bought from the grid altought it could be taken from the battery.

My batteries can provide around 7000VA easily so this can not be the problem. Also the system balances out during normal operation just fine. Is this expected behaviour for ESS? If so, why? Makes no sense to me.

Multiplus-IIESS
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2 Answers
Daniël Boekel (Victron Energy Staff) avatar image

Hi @mose


I've checked back-stage, and improving this behavior is on the 'todo' list, it might take a while to make this work and test though.

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Okay, so atm this is expected and will BE changed in the future. Will this require a firmware update to the Multis or only CCGX? Could you please inform me when this gets fixed?


From idle curriosity - being also an IT-Professional- how comes that balancing behaves differently in regards to load limit? Would expect that it should be handled the same softwarewise...?

@Daniël Boekel (Victron Energy Staff) did you see my comment? Today I noticed in the Changelogs that VE.Bus xxxx460 had "A lot of under the hood changes". Which device does need this improvement the CCGX or the Multi?

Hi @mose

these things have to be handled by the Venus device, but it is very difficult to make this work, and not a lot of systems need it. Most systems are well balanced over the phases, or not maxing out the inverters.

mose avatar image mose Daniël Boekel (Victron Energy Staff) ♦♦ ·

Thanks for the quick response @Daniël Boekel (Victron Energy Staff).
Good to know, so I now know in which changelog to look for my case. From my point of view it's very easy to create this unbalanced situation in a normal household and a three-phase MultiPlus-II 3000 setup. Simply turn on the oven which is normally one phase only. With some additional "basic" loads on that phase you can easily recreate this situation. Maybe most people simply did not notice it yet?

Daniël Boekel (Victron Energy Staff) avatar image

Hi @mose
Did you select 'phase compensation' in the settings?

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Yes, Phase compensation in ESS is on.