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rolandrrr avatar image
rolandrrr asked

Allow for higher grid-feed-in than taking from grid

Hi all I have a Multiplus-II 48/5000/70-50, a big smartsolar charger and I have a Cerbo. ESS is configured for self consumption (Optimized mode).

The situation is that the building is on a phase that has two other buildings on it. But these other buildings don't have solar on them.
So what I want is maximize the input current, for dark periods that the buildings in total do not consume to much. But the grid feed-in can be set to a much higher limit.
For example I take a maximum of 1000W from the grid (and use batteries for but I can deliver 3000W to the grid.

All the solar is DC coupled, I don't have any AC coupled solar inverters.

In the configuration of the Multiplus there is only one AC current limit and it is applied for both ways.

(I know that any excess energy gets put into the battery, so it is not wasted. But it will be wasted when the battery is full)

Thanks in advance

ESS
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2 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @RolandRRR,

The ESS system will try to draw all the power that it can from the battery before drawing from the grid.

The only time it will draw from the grid is when there is insufficient power available in the battery, and then it will only draw what is necessary from the grid to run the loads.

In the situation you are describing, if the AC input limit is restricted to less than what the load requires and there isn't any power in the battery to supplement, you will get an overload and a blackout.

Is that really the expected behaviour you want?

How was this situation managed with a limited AC input supply that is not sufficient for the load demand before the Victron system?

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rolandrrr avatar image rolandrrr commented ·

Thanks for your quick answer.
There was no "before", I have been using this system to take maximum of roughly 1000W of grid (actually a bit higher 5.7 amps because of the Multiplus) and powering any higher loads from the battery.
Now I have DC coupled solar (smartsolar) on there with ESS configured at a certain minimum battery level.

I guess I will need to do some testing with pulling 5000W or so and see if it already behaves as you say, then there is hardly any issue.

Then I only exceed the intended ~1000W from the grid when the battery is empty. Which is quite rare.

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rolandrrr avatar image
rolandrrr answered ·

@Guy Stewart (Victron Community Manager)

Ok I did some more testing. I have it in Optimized mode (without batterylife)

It does seem to work quite like you say of course. So the minimum configured SOC is the boundary.
The energy stored in the battery below the SOC limit seems only used for power outages. Because once the battery is drained to that SOC limit, the Multiplus goes into passthrough and is pulling all the power from the grid, exceeding my configured ampere limit.

I can understand how it is intended. However, my thought was, once it is drained to the configured SOC limit it would still work in the power assisting mode.

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