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Josep morancho avatar image
Josep morancho asked

Off-grid and AC output for non-critical load?

I am planning an off-grid installation where i would like to have separated output lines for critical loads (lights, refrigerator, etc) and non-critical loads (water pump, Water heater, etc).

I would like that inverter only enables non-critical loads when there is enough solar pv production and batteries are full or reached some charge level

Is this possible?

If so, what VE equipment do i need?

Thanks


MultiPlus Quattro Inverter Charger
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shaneyake avatar image shaneyake commented ·
Yes, this is possible.


What size inverter do you need? You will most likely want to use a Multiplus-II which has 2 outputs but can you share more details about your system? Battery size, planned Solar, AC PV if you have any, etc.

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Josep morancho avatar image Josep morancho shaneyake commented ·
There would be 2kw of solar panels plus 2 x 3kw of lithium batteries. Daily consumption of critical loads are around 2kw and non-critical loads (water pump and water heater) have a power of 1'5kw each but they should not start at night or in low battery charge level.


This is an off-grid system as the house is in the middle of the mountain where AC grid does not arrive.


As far as I understand, second multiplus AC output is disconnected if there is not AC grid available but perhaps can work without grid too. How?


Thanks

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nickdb avatar image nickdb ♦♦ Josep morancho commented ·

Yes, AC2 is dead if AC IN isn't powered on the multi2.


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shaneyake avatar image shaneyake Josep morancho commented ·
AC Out 2 is fully programmable. Can also be triggered from an aux input. I normally use the Cerbo relay to trigger aux input on the inverter to control AC2, this gives you the most amount of control. You can also turn off AC2 above a certain load to prevent inverter overload.


So AC OUT 2 can be used in anyway you want it. I would go with a Multiplus-ii 48/5000 if you can. It is a very reliable inverter and can be connected to a generator in the future if you needed.

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nickdb avatar image nickdb ♦♦ shaneyake commented ·

Was under the impression the mp2 ac2 is directly connected to ac in via a relay and it can't be switched. Quattro yes. When did this change?

EDIT: I see this changed from rev3 onwards


screenshot-2022-04-26-at-164328.png

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screenshot-2022-04-26-at-164328.png (306.7 KiB)
shaneyake avatar image shaneyake nickdb ♦♦ commented ·
This was never the case with Multiplus-ii as far as I know. Multiplus had this limition early on.
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nickdb avatar image nickdb ♦♦ shaneyake commented ·

Victron docs very much show that the MP2 (part numbers in the diagram above) rev2 and below were like this.

https://www.victronenergy.com/upload/documents/MultiPlus-II-to-MultiGrid-and-MultiPlus-comparison-EN.pdf

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shaneyake avatar image shaneyake nickdb ♦♦ commented ·
That makes sense, I haven't used or come across such an early model. I think the current rev is 16 but would have to check.
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nickdb avatar image nickdb ♦♦ shaneyake commented ·
I never bothered to try use the AC2 out with ESS during grid loss as this was the myth, so assumed it to be true.

I have the use case to power AC2 from AC1 when grid has ceased to be, but with ESS assistant running.

I will have to go investigate how.

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Josep morancho avatar image Josep morancho shaneyake commented ·

Many thanks!

By the way, would it work also with EasySolar-II GX 5kVA?

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shaneyake avatar image shaneyake Josep morancho commented ·
Yes, it is the same for the EasySolar-II
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