question

Dieter Buchholz avatar image
Dieter Buchholz asked

Dynamic ESS not working correct in Green Mode

Hello,
after I have converted all the counters to use the Victron DESS and after weeks of trying out the DESS I am finally quite frustrated, I just can’t get it to work properly.

I have an MPII GX with 4 PV systems in the meantime. in AC and DC operation. This all works wonderfully with normal ESS, when I then turn on DESS in green mode, the following happens after about 3 days: The target SOC of the DESS is adhered to come hell or high water, which means that neither excess PV energy is taken into the battery nor missing energy from the battery. Then, if the target SOC is increased in the next hour and PV energy is not sufficient, the battery is charged from the grid.

That’s exactly what Green Mode was supposed to prevent - unfortunately it doesn’t work for me.
I’ve read quite a few posts about this problem, actually the Green Mode should have fixed all these problems, why not for me?

System MPII GX with 3.4.1 large without beta in pure VRM operation
Battery 7 kWh self-made with external BMS without connection to the MPII GX
16 kW PV systems AC and DC operation with fixed feed-in tariff
Electricity provider Tibber with dynamic prices
VRM ID: c0619ab10be7

I am grateful for any help or experience reports…

Greeting
Dieter

dynamic ess
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2 Answers
wilm avatar image
wilm answered ·

Hi Dieter,
how should the VenusOS know the SOC of your battery, when there is no communication? You should either use a BMS which supports the communication with Victron, or add a SmartShunt to the system.

Best,
Wilm

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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·
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