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jlaaij asked

Prevent overload MPII or batteries with 'small' ESS <> load

Hi,

My basic ESS will be:

- Grid

- Energymeter ET112 on grid

- All loads connected to grid

- Multiplus II 48/3000 + Cerbo GX- AC-in connected to grid

- PV system (Hoymiles micro-inverters)

- connected to MPII AC-out 1 or 2 (obeying to factor 1.0 rule)

- Battery Pylontech, 1x US5000 or 2 US3000C


Overall average max usage 500W daytime / 250W nigthtime.

Power of the MPII 48/3000 or batterie(s) will be exceeded by hotwater boiler (max 2.7kW) or induction cooker (max 3.7kW/3.1kW).

Boiler and induction cooker will not be used at the same


My questions are:

1. Will the MPII be able to timely add power from grid to avoid overload to itself and/or battery? Latency?

2. Any other means to overcome overload by settings MPII?


Thanx Jaap

Netherlands

Multiplus-II
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2 Answers
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ejrossouw answered ·

A grid parallel ESS system (one that is synchronised with the grid) https://www.victronenergy.com/media/pg/Energy_Storage_System/en/ess-introduction---features.html allows any shortfall of the 2400W the MP II 3KVA can supply, or any system for that matter and transparently to you, to be complimented with power from the grid when otherwise an overload may have occurred as would be the case with off-grid systems. Off-grid system are different in that they are switched between grid only or inverter only modes, unlike the ESS described above. Domestic systems are configured in this way and have to conform to local rules and regulations.

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jlaaij answered ·

Thanx @ejrossouw for your answer.

I will also be implementig a grid-meter (ET112) and set to '0' grid.

I 've read there is concern about the ET 112 latency that is mentioned of up to 20sec if a sudden high load is added

Any thoughts of experience with this?

Greetz Jaap


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ejrossouw avatar image ejrossouw commented ·

@jlaaij A CT offers better response times as would the new Victron energy meter. Depending on various factors I found the ET112 resulted in approx 0.6kWh as opposed to the CT 0.1kWh drawn from the grid on a 5kVA install with household consumption of about 9-10kWh a day. Not that significant depending on who you ask ;)

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