question

tubeman avatar image

Peak shaving while charging from grid

I am looking at buying a Multiplus 48/3000/35-32 with the GX controller to combine with a 16kWh BYD battery and solar panels. I looked through the documentation but could not find information on my use case.

One of the reasons that I want to buy this setup is to do peak shaving. From what I understand from the documentation, the default setting is that you do ‘peak shaving’ when the battery is full but that it will shave to (close to) 0W. When the battery is depleted, peak shaving will stop and you will go to the grid for 100% until the PV charges the battery again or you specify a charging window from the grid after which it will resume.

The issue I have with this setup is that (most probably) next year, we are going to be taxed based on the maximum power demand from the grid in a 15 minute window over a month. So using 10kW during 15 minutes anytime in the month will determine the amount we are taxed and each higher peak value will be much more expensive than the lower one. The goal for the peak shaving would be to reduce this maximum peak but when the battery would be depleted early in the afternoon, generating a single high 15‘ peak in the evening at any time during the month will make the battery investment worthless for this purpose.

I did find that you can set the grid power but that seems to always apply and in December for instance, I have days that only 10kWh is used at the moment but also days with 50kWh. Setting the grid parameter to 2kW would mean that the battery is not used at all during the 10kWh day but would still be depleted after a few hours on the 50kWh day in turn causing a power peak once the battery is depleted. As the goal is also to use the battery to charge during the off-peak hours and use that energy during the day, not using the battery on the 10kWh day will negate the benefits of the cheaper off-peak energy cost.

My question now is: is there a way that you can set a certain limit (e.g. 40% charged) after which the battery starts charging from the grid at e.g. 3kW up to e.g. 70% but when there is a total power request from the grid of e.g. >6kW during the charging, it will kick in and deliver the requested power above 6kW and starts charging to the requested limit again once the power drops below 6kW? When the charging is done, it can return to 100% peak shaving to (close to) 0W down to the 40% level at which the charging starts again. In short, I want to set a limit on the power drawn from the grid at all times and the battery would have to do peak shaving when the demand is higher and charge itself (from the grid if there is no PV) to a certain level when there is less demand while still offering the peak shaving during the charging.

If this can be done through an API or other interface that would also work but (again, from what I understand) the battery would not be used at all during a charging window which might again lead to peaks while charging which is what I wanted to avoid. If this is not possible now, do you think this is something that can be included in a firmware update in the future as for the Belgian market this would be an extemely useful feature starting next year?

Multiplus-IIESS
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I am looking for the same solution, to have control on the peak shaving option. I think this is a feature that is needed in the future to support Belgium customers.

1 Answer
Alexandra avatar image
Alexandra answered ·

@Tubeman

With ess you can set times windows for battery charging as well as SOC to stop at if it is reached before the time ends.

you can set your amps from grid charging lower so you keep your current draw down as well when programming the multi.

And you can set your input current to a limit as well for the whole system.

Are you using solar as well? And just a comment on the 50kw not sure a 3kva would be able to do that in a day you may need to look at going up to a 8kva multi. Unless you were using the 6kwh as an example

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