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

2 |3000

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shaneyake commented · Apr 25, 2022 at 06:59 PM

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 shaneyake commented · Apr 26, 2022 at 08:14 AM

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 ♦♦ Josep morancho commented · Apr 26, 2022 at 08:25 AM

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

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shaneyake Josep morancho commented · Apr 26, 2022 at 02:35 PM

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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