slartybart avatar image
slartybart asked

Multiplus 2 as UPS (UK)

I'm planning an ESS system using a Multiplus 2 (48/3000), solar panels, MPPT, GX, Battery etc. All pretty conventional so far. When it's installed in France, where I subscribe to a 9000va service I can reconfigure my consumer unit so critical loads are supplied from AC out 2, and everything else is connected to the AC out 1. So far so good. In this case the Multiplus will boost the grid supply (from PV and battery) if five people decide to dry their hair, boil a kettle, make some toast (or whatever) when the grid is connected, and in the case of a power cut they'll have to suffer wet hair, wait for breakfast and have no tea, but the lights and wifi will still be on. I say its relatively easy because the house wiring there is made up of simple radial circuits, limited by the size of individual breakers, maximum eight sockets on a 16amp breaker, cooker, washing machine, fridge etc on individual breakers and so on and so I know which circuit goes where and can easily choose which circuits are critical and which aren't.

Now for the question: In these unusual times I want to temporarily install some of the equipment (Multiplus, GX and Battery) in a different house (in the UK this time) to provide a grid backup UPS system. Here the entire house is supplied by far fewer ring main circuits, some of which are relatively low demand, lights for example, but other circuits potentially much higher. Here the only source of power is the Grid (no solar), but in this case it's a 100amp supply. Is there a limit to what can be powered through the Multiplus 2? In other words, do I need to constrain what's being supplied by AC1? Or, to put it a third way can EVERY non critical load (potentially up to 100amp) pass through the AC-in and back out again through AC2. (There's no need to use the 'boost' element of the Multiplus system here as I'm paying for the power whether it comes from the grid or via the battery anyway.)

Presumably I'll have to reconfigure this consumer unit and rewire the house to separate what's critical and what isn't to ensure the UPS isn't drained within the first hour of a power cut by teenagers making toast.

BUT can I separate off critical loads to AC-2 and leave everything else to AC-1 - or am I better NOT connecting AC1 at all?

Thanks in advance for everyone's time.

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2 Answers
JohnC avatar image
JohnC answered ·

Hi @SlartyBart

Your Multi II is listed as 32A input capacity. Add to that peaking loads and another 10+A is available from batts to top off. And that's it.. but it's still a lot of power.

Your '100A' supply likely exists to (potentially) supply massive users like water heating and/or aircon. And you mightn't want that to run through the Multi anyway.. no point. Akin to AC2 OUT, no grid, no power. And anything you don't want running when grid is down needn't go through the Multi anyway.

AC1 OUT is for your critical loads like lights, tv, toaster, whatever. The output of your ups..

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slartybart avatar image
slartybart answered ·

Much appreciated, that’s what I thought. Will make the rewire easier too.

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Related Resources

MultiPlus-II Product page 

MultiPlus-II Manual

MultiPlus-II 230V Datasheet 

VE.Bus Error codes

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