DESS does not follow negative AcPowerSetpoint on 3-phase Multi RS, manual ESS export works (BUG)

Q&A and troubleshooting DESS
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1

I have a 3-phase system with:

  • 3x Multi RS 48/6000VA, firmware 1.31

  • Cerbo GX MK2, Venus OS 3.75

  • VM-3P75CT, firmware 1.11, connected via wired Ethernet

  • VM-3P75CT configured as grid meter

  • Energy meter support enabled on all three Multi RS units

  • Dynamic ESS enabled in Trade mode

  • Battery-to-grid discharge allowed

  • Grid feed-in allowed

  • No system feed-in limit configured

The issue is that DESS schedules battery export, and the D-Bus setpoints are correctly sent, but the Multi RS units continue regulating the grid around 0 W instead of exporting.

During one test DESS commanded:

com.victronenergy.acsystem.socketcan_vecan0_sys0

/Ess/AcPowerSetpoint = -12784 W

/Ess/UseInverterPowerSetpoint = 0

/Ess/InverterPowerSetpoint = invalid/unset

/Ess/DisableFeedIn = 0

/Ess/DisableDischarge = 0

The target was also correctly distributed to the individual Multi RS units:

  • RS L1: approximately -4221 W

  • RS L2: approximately -4216 W

  • RS L3: approximately -4232 W

On every RS:

/Ess/EnergyMeterInUse = 1

/Ess/DisableFeedIn = 0

/Ess/DisableDischarge = 0

ErrorCode = 0

Despite this, actual grid power remained approximately 0 W. The individual Multi RS AC input power readings were also approximately zero, while the battery only discharged enough to supply the local loads.

The VM-3P75CT likewise showed grid power close to zero instead of the requested roughly -12.8 kW.

I then performed an A/B test.

I disabled DESS and manually configured a negative ESS grid setpoint of -1000 W per phase.

The system immediately exported correctly:

  • L1: approximately -999 W

  • L2: approximately -998 W

  • L3: approximately -996 W

  • Total grid export: approximately -2993 W

Battery discharge increased accordingly and the Multi RS units followed the manual negative ESS setpoint almost exactly.

This appears to show that:

  1. Grid feed-in itself works.

  2. The VM-3P75CT works.

  3. The three Multi RS units can follow negative ESS setpoints.

  4. DESS calculates and writes a negative /Ess/AcPowerSetpoint.

  5. The setpoint reaches each individual Multi RS.

  6. However, when DESS/external control is active, the system regulates towards approximately 0 W instead of following that negative setpoint.

Is this a known issue with DESS + dbus-acsystem + 3-phase Multi RS?

I can provide dbus-spy screenshots showing the system-level and per-inverter setpoints, VM-3P75CT measurements, and the manual export test.

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23448×396 140 KB

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51920×978 156 KB

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4

It is a (this week) discovered issue with the Multi RS (no solar) and general forwarding of the ESS-Setpoints to the Multi RS.

It has already been fixed in venus 3.80~42 I just read.

3.80 should be released officially in the not to distant future, but you could switch to the beta to verify. (The GX has a builtin-option to roll back to the prior version at any time)

5

Thanks so much, it was driving me crazy! i’ll try that first thing tomorrow.

6

It is fixed in beta 3.80 v42!

thanks again!

7

There should be a 3.7x production version coming in the interim to address the issue, for those who do not want to run betas.

8

Is this issue resolved?

I have similar issue.

Multi RS 6000 MPPT will charge battery correctly in DESS.

It will export correctly when DESS is off and grid setpoint set to for example -1000W.

But when DESS is on, the Multi RS will not feed the grid.

9

Yes fixed also in production 3.79!