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vovarpd avatar image
vovarpd asked

Multiplus. Charging at night, discharding during the day

Hello.

I'm going to build a pretty simple system for life during power outages here in Ukraine.

1. Multiplus 24/1600/40 + Venus GX

2. Lifepo4 custom DIY battery

We have a night price at 50% of the day price.

So, I want to charge my batteries during the night (grid priority, so the PowerAssist function is fine for high loads) and discharge them during the day with battery priority.


So, the main question is a battery priority during the day.

For example, I have a Multiplus 24/1600, but I need to run a kettle 2000W. Is it possible to use 1300W from batteries and the remaining 700W from the grid?


Could anyone point me out to the docs, on how I can implement it? ESS?

Do I need a separate Anti-islanding relay? I'm not going to sell anything into the grid.


Thank you.

1718472426412.png

MultiPlus Quattro Inverter Charger
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2 Answers
fbo avatar image
fbo answered ·

Hi,


sounds like regular ESS operation to me. Just define a setpoint of 0W and set a charge schedule (at the bottom of the ESS menu) during the night. The Inverter will try to keep up with your loads and take the remaining power from the grid.


Frank

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vovarpd avatar image vovarpd commented ·

Thanks. It's mostly clear now.


So, if I want to prevent any suddenly feeding back to the grid, should I set the value a bit more than 0W?

It's OK for me to use some small amount of grid during the day.

This sets the point at which power is taken from the grid when the installation is in self-consumption mode. Setting this value slightly above 0W prevents the system from feeding back power to the grid when there is a bit of over-shoot in the regulation. The default value is therefore 50W - but should be set to a higher value on large systems.

https://www.victronenergy.com/media/pg/Energy_Storage_System/en/configuration.html

What about `anti-islanding`? Is the external device required for my use case?

I see the next note:

ESS always requires anti-islanding. This is also true for a No feed-in-system.


https://www.victronenergy.com/media/pg/Energy_Storage_System/en/system-design.html#UUID-7c21d64c-8be3-5162-abc8-027577d36a7a


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jalle19 avatar image jalle19 vovarpd commented ·

You don't need a separate anti-islanding box, the MultiPlus will handle it automatically when configured with a grid code (see https://community.victronenergy.com/questions/132031/ess-violate-anti-islanding.html).

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fbo avatar image fbo vovarpd commented ·

AI is done automatically by the Multiplus. About "sudden feeding back": It depends on the time frame. In ESS mode, the Multi always sets its Inverter to a power output that results in the desired setpoint on ACIN. However, sudden changes in the Load on ACOUT will always cause some current going through ACIN in either direction. But Multis are quite good at keeping this to a minimum.

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Duivert NL avatar image
Duivert NL answered ·

Multiplus 2 has anti islanding, not sure about older multiplus (1)

Also ESS will always feed a little to grid to balance even with high positive gridsetpoint

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