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dazza666 avatar image
dazza666 asked

Which inverter for pylontech batteries, UK

Hello everyone

So, I have been researching batteries for a while and I think I have settled on the Pylontech Us3000C 4.8KWh. The main reason for this is the modularity of the system, as space is a little constrained, but with these I can put them in the eves of the converted barn we live in. I think I want to pair this to a Victron MultiPlus-II 5000VA, but maybe the Quattro 48/8000. I am not sure...

My plan is to eventually get 10 batteries to ensure capacity during the winter months, but I plan to start with 5-6, 6 Batteries will give me around 27KWh usable when fully charged as I understand it.
The general idea is to charge the batteries up during the night on a cheap tariff, and then discharge them during the day (solar is not currently an option)

Now, this is where a gap in my knowledge appears, I don't know a great deal about inverters, regarding how fast I can charge the batteries etc

I want to be able to charge them at 7KW, for a period of 4 hours, is that achievable? I am on single phase I also want to be able to power the house from the batteries when we have a power cut, ideally automatically but I will settle for some kind of manual switch over if this is not possible

How long can they sustain a load of say 3-4KW, will they be able to do this for 3 hours at a time?

Is there anything else I need to consider? I don't suppose anyone knows of a good installer in Kent do they?


Many thanks

Multiplus-IIMultiPlus Quattro Inverter Charger
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3 Answers
dmsims avatar image
dmsims answered ·

Before doing anything I would audit your energy usage (consumption and time of day)

Which tariff are you on ?

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wkirby avatar image
wkirby answered ·

The US3000C is a 3.55kWh model, not 4.8kWh, so that might throw your calculations off. The Pylontech UP5000 modules are 4.8kWh
Sure, calculate your consumption if you have not already done so.
A 7kW charge power would require a charger capable of ~140A to the battery. This means that you'd need at least a 10kVA Quattro for that kind of charging power.
US3000C batteries can sustain a charge / discharge current of 37A or ~1.8kW per module. So if you want to charge at 7kW you'd want a minimum of 4 modules, but with a 10kVA discharge power from the inverter you'd want in minimum of 6 modules. This number is your long term aim, but 2 modules will be no good even in the short term.
So with a minimum of 6 modules, you have ~21kWh of capacity. A 3-4kW load will last between 5 and 7 hours.
Charging at 7kW for the 4 hours would theoretically yield 28kWh from the Octopus, but there will be losses to account for and battery charge current is reduced at the upper end of the charge.
That's a bit to digest, but do ask if you have anything further.

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seb71 avatar image
seb71 answered ·

Also check if you can draw that much power from the grid. Besides charging the battery, there might be other AC loads in your house at the same time, so the total power might be too big.

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