Victron sets DC Offset too low -> MPPT throttled down

[Edi223]

Hello,
I’ve been having a problem with my setup for a while now and hope you can help me.
As soon as the CLV (53,6v) is reached, the MPPTs throttle down and the batteries continue to be charged slowly by the AC inverter (CCL = 160A). Even though DC feed-in should be working, and the Multiplus should be pushing the excess DC into the grid.

-ESS is configured (optimized without BatteryLife)
-DC Feed In is enabled
-DVCC enabled (55,2v) → JKBMS

After an indeterminate period of time, however, both MPPTs begin feeding the DC into the grid. This process repeats itself every day.

I have been trying to identify and solve the problem for over a year now, but without success.

Greetings
Edi

[MikeD (Mike)]

There is probably some problem with the CVL that the JKBMS is reporting to the cerbo.

see also MPPT getting wrong Charge voltage limit from Cerbo/ESS - #11 by MikeD

for more details. With ESS configured, the MPPT’s should be getting a CVL 0.4V higher than the inverter, to prioritise solar charging and to export solar to grid if this is permitted. Use ssh to access the cerbo’s root level, and dbus-spy to check the CVL sent to inverter and MPPT’s.

[Edi223]

I found this Information, hope this will help.

For me this values looks correct…ChargeVoltage of MPPT is 0,4v higher than CVL from BMS and Multiplus.

com.victronenergy.settings
SystemSetup/MaxChargeVoltage → 55.20v

com.victronenergy.system
Dc/Battery/ChargeVoltage → 53.65v

com.victronenergy.vebus.Multiplus
/BatteryOperationalLimits/MaxChargeVoltage → 53,65v

com.victronenergy.solarcharger.MPPT_Garage
/Link/ChargeVoltage → 54,05v

com.victronenergy.solarcharger.MPPT_Nord
/Link/ChargeVoltage → n.a.?

com.victronenergy.battery.JKBMS (dbus-serialbattery)
/Info/MaxChargeVoltage → 53,65v

############### EDIT #############

I checked the values ​​again.

The MPPT com.victronenergy.solarcharger. /Link/ChargeVoltage is no longer at 54.05V. It has now changed to 53.65V?

It looks like the value is unstable, fluctuating between CVL 53.65 V and CVL +0.4 offset. However, I don’t understand what’s affecting this.

############### EDIT 2 #############

Now I checked in dbus-spy the System/Debug/BatteryOperationalLimits/SolarVoltageOffset. It was set at 0.

I set it vom “0” to “0.4”. Now the MPPT /Link/ChargeVoltage → shows me “54,45v” (0,8v over CVL).

Although the CVL has been reached, both MPPTS are currently operating continuously.

However, the debug settings are only temporary until the next reboot. So this can’t be the final solution…

[Edi223]

Does anyone have any idea why Victron isn’t setting the DC offset for the MPPT correctly? Is it a BUG?

Until I can find a better solution to the problem, I’ve devised the following workaround. Using WinSCP, I set the preset value “/Debug/BatteryOperationalLimits/SolarVoltageOffset’, value=0.4” in the file
“/opt/victronenergy/dbus-systemcalc-py/delegates/dvcc.py”. Should the integrated offset calculation actually kick in, I’ll then have an offset of 0.8V above the CVL value. I think the MultiPlus doesn’t care whether it’s feeding in 0.4V or 0.8V.