ESS Charge during day, discharge at night

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nickseghers asked Oct 8, '22

ESS Charge during day, discharge at night

Hello All,

I have a 48V 5Kw Pytes battery with a Multiplus II 48V 5KVA.

I have a 3phase grid connection with a 3phase SMA grid inverter.

I added the Victron Multiplus II and battery to charge the system during the day and use the energy at night. I have set up the ESS assistant to charge from 7:00 to 22:00. After that night meter starts and we don't want to use electricity at night. The reason for this is that we overproduce during the day and overconsume at night.

Now the problem is that the batteries don't discharge.

Questions:

- Do I need to connect the AC out to the grid? I thought AC in-out can go over the same wire.

- Is there something wrong with my ESS config?

Multiplus-II ESS ess discharging

setup.png (4.8 KiB)

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Answer 1 · 2022-10-08T14:34:14Z

Alexandra answered · Oct 08, 2022 at 02:34 PM

@nickseghers

If you connect AC out to the grid, you will kill your inverter.

Ac out should connect to your loads in your household.

Set your SOC in case of grid faliure down to allow them to discharge to your loads at night.

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nickseghers commented · Oct 08, 2022 at 04:56 PM

Thank you for your reply Alexandra.

I have added another schematic for clarification.

All the loads to the house leave from the main AC switchboard.

- Isn't connecting the AC-out from the Multiplus to the AC switchboard the same as connecting it to the grid?

- Yes, I have set my SOC to 10%

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setup2.png (13.5 KiB)

Answer 2 · 2022-10-08T14:35:32Z

sesshoumaru answered · Oct 08, 2022 at 02:35 PM

Hi

I am not an expert, but if you have the loads not connected on AC-out of the Multiplus, how is the Multuplus supposed to know that it needs to shove out power on AC-in? You need to have a grid meter which tells the Multiplus when power is drawn from the grid, to start to discharge so that the grid set point it kept at 0W.

I hope that made sense....

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nickseghers commented · Oct 08, 2022 at 05:01 PM

Yes, that makes sense. When the energy meter sees a load between 22:00 and 7:00, the multiplus will put the same amount of energy out. I have a 3phase system, so I assume I need the EM24? Is it a problem that the multiplus is only one phase?

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