How to install MultiPlus-II AC system in a detached garage

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awbower asked Nov 15, '22

How to install MultiPlus-II AC system in a detached garage

I have a detached garage that is powered off a subpanel fed from the main house (grid > main house > detached garage). I would like to install solar on the roof of my detached garage and have the MultiPlus-II and batteries inside the garage. It would be setup as an AC system. I would like to do this while maintaining my grid connection.

With the whole system in the detached garage, there is no easy way to wire power from the meter directly into the AC-in side of the MultiPlus-II. My question is: can the MultiPlus-II interface with the grid on the AC-out side? In this way, the grid would just appear as an additional power source on top of what the PV panels are producing.

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Answer 1 · 2022-11-15T04:25:23Z

Kevin Windrem answered · Nov 15, 2022 at 04:25 AM

Not the AC output but you can connect just the AC input of the Multi like you would a grid-tied solar system. You need a grid meter that is between the Multi, solar and your loads, and the grid and I'm not sure how you could make that connection since it would be in your house not the detached garage.

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awbower commented · Nov 15, 2022 at 05:29 AM

So you're saying wire the grid and the solar into the AC input of the Multi. That I can do.

Could you draw a diagram of where the grid meter would go? I'm a bit confused as to how that would be wired.

Thank You

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Answer 2 · 2022-11-15T05:44:24Z

Kevin Windrem answered · Nov 15, 2022 at 05:44 AM

Like this:

https://www.victronenergy.com/media/pg/Energy_Meter_ET112/en/image/163578121491b5.svg

but no loads on AC 1 out or AC 2 out

All your loads would be after the grid meter but before the Multi as shown in the brown wiring. PV Inverter would also go here as well.

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awbower commented · Nov 15, 2022 at 11:11 PM

Since the ET112 is only rated for 100A, would this configuration limit me to drawing a maximum of 100A from the grid?

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niborb awbower commented · Nov 16, 2022 at 10:41 AM

What size fuses do you have on your grid supply?

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Answer 3 · 2022-11-15T05:52:15Z

Kevin Windrem answered · Nov 15, 2022 at 05:52 AM

BTW, with this arrangement, the Multi can assist the grid but if the grid goes down the Multi can NOT feed the loads since the AC input relay will open because no grid is present.

The only way to run loads off the Multi with the grid down is to connect them to the Multi's AC 1 output. This would require additional feeder wiring in your situation.

A better approach would be to locate the Multi near the service entrance. Your existing PV inverter could connect to the Multi's output if certain criteria are met:

https://www.victronenergy.com/live/ac_coupling:start

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Answer 4 · 2022-11-16T12:06:36Z

sharpener answered · Nov 16, 2022 at 12:06 PM

There are various ways of extending the ET112 wiring over long distances that you can find on this forum, including wireless links. But AFAIR there is no officially endorsed way of doing it.

Also you may have difficulty getting DNO approval for a setup like this because it doesn't meet the requirement for the Multi to have its own RCD not shared with the other loads.

And as @Kevin Windrem says you will not have a UPS capability.

On the other hand you will not be troubled by fan noise if the Multi is in the garage.

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