question

Yes, I see this type of usage a lot on other solar forums with inverters from other manufacturers (SBU mode on Voltronic clones), in cases where ESS cannot be used (e.g. high grid voltage during the day due to too many prosumers exporting energy to grid). I wish I could recommend the Multi RS solar to people who ask for a Victron solution, but I can't.

The VE.Bus inverters can achieve this functionality with assistants and advanced configuration, but when you add in the cost of a MultiPlus, an MPPT RS and a BMV 712, it quickly becomes un-competitive with Chinese clones. I know people who would pay the cost of a Multi RS to get into the Victron ecosystem, but not the cost of a MP-II 5K + MPPT RS 450/100A + BMV712

@Alex Pescaru wrote:

"Don't charge batteries from grid".

In this way, when you function in self-consumption mode, and you don't have solar for a few days and the SOC drops below a specific value, connect the grid, consume from grid, but Don't charge from grid."

Love the idea! Something that is also missing in the standard settings of Multiplus-II's ESS system.

But with MP-II ESS, it can be replaced by an extensive NodeRED script managing grid setpoint to accomplish same (or almost, as AC-PV capping is badly reacting to changes in grid setpoint, quickly ramping down and very very very slowly ramping up, loosing tons of PV production).

Explaining what I mean for this feature for ESS:

There is a setting "Minimum SOC (unless grid fails)", and if you set that higher than actual SOC, MP-II's immediately start charging (respecting maximum AC current input limit) batteries, despite strong solar here charging too.

Either an ESS setting "But Don't charge batteries from grid" complementary to "Minimum SOC unless grid fails", or a second setting "Minimum SOC (PV charging only)", that would only use excessive PV power (above running the loads), and no grid.

Maybe I missed a setting for that, but don't see which.

Don't charge batteries from grid" - great idea!

option should save me a lot of time. Now only the passthru feature does this. In dark days my batteries are empty (~20%), and before going to sleep, I usually switch to passthru and in morning back to ON mode. I tried to find a method switch to passthru automatically, but neither Modbus, nor NodeRed, nor I/O function doesn't have ability to switch to passthru mode. (Anyway: Why???)

Xmas and my birthday is over, but it would be very nice to have "Don't charge batteries from grid" function as an Easter egg.

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Reasons:

1. Charging from grid and consuming from batteries later has a 15%-20% waste of energy.

2. It reduces the lifespan of the batteries.

3. My batteries are to store the extra solar energy. If I've charged it from grid, there is no room to store the (free) solar energy. In the morning it is better to start by empty batteries!

Hi all,

I think that the main reason why people want this feature of AC disconnecting based on battery SOC is the fact that they (like me) observed this issue of battery being slightly charged from the grid in some cases. It is not about a "fake" energy that's being displayed, it's actual power going into the battery. It's verifiable if we multiply the battery voltage and current going into it. Usually it's not much (approx. 200 - 400 Watts) but that's enough to reduce your battery storage available for solar energy.

This behavior doesn't happen all the time. There are times when only the PV energy goes into the battery and the house continues to consume from the grid (AC connected). Also times when PV energy goes into powering the house and charges the battery and the grid consumption is around 0W with AC relay closed.

So, if we need to live with this residual power going into the battery some times, an AC input disconnect based on SOC would be very useful to have...

Thank you!