hominidae avatar image
hominidae asked

how can I force chargeing from PV only / disable feed-in until batteries are full

Hi Folks,

during winter season, daily PV yield is not sufficient to fully recharge the batteries, especialy when direct consumption is also part of the usage.

My DSO does allow PV feed-in but does not allow chargeing from grid.

Using battery life alone, it would take weeks until a SoC of 100% can be reached, because discharging would still be allowed.

I'd rather find a solution to use almost all (and only) PV for chargeing, as well as prevent discharging until a SOC of 100% has been reached.

What would be the best option, given that I have Node-Red and the Cerbo with activated mqtt at hand?

My first guess is, to set the grid-setpoint to the value of the actual grid-consumption (so direct usage of PV will not take place, as all PV will be used for chargeing the batteries) .... do this until SOC of 100% has been reached, then return to a standard grid setpoint.

When minimum SOC has been reached, restart that procedure.

cerbo gxgridNode-REDbatterylife
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1 Answer
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @Hominidae,

Why not just manually set the ESS minimum discharge SOC to 95% so that the PV will always first go to charging the battery, and it won't be discharged below that (unless grid fails).


Then set the MultiPlus charge current limit to 0A so that it doesn't charge the battery from the AC input (but still allows pass through to the loads) as required by your DSO?

I think that should cover your limitations there?

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hominidae avatar image hominidae commented ·

Hi @Guy Stewart (Victron Community Manager),

thank you very much for your answer.

I forgot to mention, that all my loads as well as the PV inverter are on AC-In. So what you suggested will not work for charging the batteries, won't it?. The Victron system is a retro-fit / add-on as the AC coupled PV has been installed several years ago.

Hence my idea of of "tricking" the ESS system of the GX into a state where the grid setpoint would allow for PV energy to be available to charge the batteries. If the power available for charging is deemed less than the actual power available from PV (i.e. calculated as 90% of actual PV), there will be no (noticeable) consumption from the grid for charging the batteries.

So the value given at the grid-setpoint would be calculated as "actual Grid Power + 90% of actual PV power". This would prevent feed-in and leave that 90% of PV for charging.

I would need some extra rules to take into account the SoC and allow discharge again, once 100% has been reached, then reopen the procedure when min-SoC has been reached ... and again, and so forth.

Maybe, what I have in mind is a simpler version of this:

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