question

awalkerinuk avatar image
awalkerinuk asked

Multiplus II wired in Parallel to grid - can ac out be switched to ac in on grid loss?

I am just interested if this can be done at the moment, as UK may have rolling energy black outs in winter.

My Multiplus ii is in parallel to the grid with ac side solar and a 3.55KWH Pylontech battery, nothing on AC out except a double plug.

Can the Multiplus ii ac out be switched to the ac in to run the house on the battery, it would only be used for back ground 300wH nothing high powered

I realise grid might need to be switched off for safety

Thanks for the help

Multiplus-IIgrid
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3 Answers
gazza avatar image
gazza answered ·

The quick answer is "yes", with a few provisos.
1)The grid should be disconnected (physically with an isolator switch, either at your consumer unit location or sometimes where your utility meter is?), so you are simulating "off grid".
2)A three position, three pole manual switch can do the switchover from AC In connection to AC Out 1 close to your Multiplus. It is important that the AC In and AC Out Neutral is NOT shared, the common output from the switch would be your connection back into your house wiring via whatever suitable MCB you are using at the moment to feed your Multiplus? This of course will be to protect the cable and will be the limiting factor on supply. The three position switch is advisable so you have a definite "Break before make" on changeover.

So, you have a power cut... you Turn OFF your grid mains input, you make sure you have no High demand loads on your house system. You goto your changeover switch and switch to AC Out 1 on the Multi. Limited power available until you meet your SOC lower limit, if it happens to still be daytime then you still have PV charging.

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Rob Duthie avatar image
Rob Duthie answered ·

Hi


You can try this way which i have tested done for whole house backup. Don't need to split the house up at all,

The grid runs as per normal though out the house when you have a power cut the transfer changes over so the inverter supply the whole house, also you can have AC coupled PV inverter on the out as well to save battery power during the day.

So when the power comes back on it changes back to grid power wit the victron and grid tied inverter supply power and exporting again.

The ATS i use is by Smartgen and is 125Amp single phase with a Auto controller 520N


Solar Projects Grid Tied Systems-Generic ATR System.pdf

Solar Projects Grid Tied Systems-ATS RD Design.pdf

Regards

Rob D

NZ


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Warwick Bruce Chapman avatar image
Warwick Bruce Chapman answered ·

I’m not following.


Usually you split your household circuits into essential and non-essential.


The essential are powered from the output of the MultiPlus and are sized appropriately. The non-essentials remain on the input side of the inverter and go off when the grid goes away.

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awalkerinuk avatar image awalkerinuk commented ·
Yes I agree Multiplus II is in garage and ac out would cover the freezers local to it.

But I was interested if it could temporarly run the house with different wiring scenario.

Thanks


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