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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

Hello Dazza, welcome to the forum.

Do you have a link for a spec sheet for the specific battery? I can only find US3000C at 3.6kWh or US5000 at 4.8kWh. The data in there should answer a lot of your questions - e.g. they need to be charged at 53V and maximum continuous current discharge at 48V of x Amps with a useable DoD of 90% therefore compatible chargers/inverters will need to match.

These batteries are in the 30-40 kg range so wherever you put them inside the house it will need to be practical to get them there, plus the floor needs to be up to supporting the total weight ~250+ kg for 6 plus some margin for safety. The eaves may be a bit of a stretch. Ideally you want them where they can be positioned from a sack truck and then not moved, which sort of dictates the ground floor. Position in relation to the main consumer unit will be a factor as well - you wouldn't really want them at the opposite end of the house.

The "Victron MultiPlus-II 5000VA" has a battery charging facility of only 70A circa 3.5kW

The "Quattro 48/8000" has a battery charging facility of 110A circa 5.5kW

Therefore both won't charge at a rate of 7kW as you want but in any case you wont be able to exceed about 100A 5kW with the standard cables unless you parallel up two stacks.

This link gives you some info about using the Pylontechs with the Victron kit including how to parallel up two battery stacks.
https://www.victronenergy.com/live/batt ... export_pdf

Galahad wrote: ↑Thu Jul 14, 2022 5:02 pm Hello Dazza, welcome to the forum.

Do you have a link for a spec sheet for the specific battery? I can only find US3000C at 3.6kWh or US5000 at 4.8kWh. The data in there should answer a lot of your questions - e.g. they need to be charged at 53V and maximum continuous current discharge at 48V of x Amps with a useable DoD of 90% therefore compatible chargers/inverters will need to match.

These batteries are in the 30-40 kg range so wherever you put them inside the house it will need to be practical to get them there, plus the floor needs to be up to supporting the total weight ~250+ kg for 6 plus some margin for safety. The eaves may be a bit of a stretch. Ideally you want them where they can be positioned from a sack truck and then not moved, which sort of dictates the ground floor. Position in relation to the main consumer unit will be a factor as well - you wouldn't really want them at the opposite end of the house.

My batteries are in the attic. Getting them there wasn’t much fun, but I went for the US2000 which are 25kg each. The US3000 might seem slightly more cost effective on paper but once you factor in the inconvenience of permanently damaging your back it doesn’t seem as worthwhile. US5000 are only specified by people who are paying someone else to install them!

Galahad wrote: ↑Thu Jul 14, 2022 5:02 pm Hello Dazza, welcome to the forum.

Do you have a link for a spec sheet for the specific battery? I can only find US3000C at 3.6kWh or US5000 at 4.8kWh. The data in there should answer a lot of your questions - e.g. they need to be charged at 53V and maximum continuous current discharge at 48V of x Amps with a useable DoD of 90% therefore compatible chargers/inverters will need to match.

These batteries are in the 30-40 kg range so wherever you put them inside the house it will need to be practical to get them there, plus the floor needs to be up to supporting the total weight ~250+ kg for 6 plus some margin for safety. The eaves may be a bit of a stretch. Ideally you want them where they can be positioned from a sack truck and then not moved, which sort of dictates the ground floor. Position in relation to the main consumer unit will be a factor as well - you wouldn't really want them at the opposite end of the house.

Sorry, I ended up tripping over myself as I haven't finally decided on the 3.6 or the 4.8 (and, I believe you can mix and match them as well so its not a one or the other situation - I might be wrong on this)
So a spec sheet for the US5000 can be found here:

https://prismsolar.co.uk/wp-content/upl ... -48V-2.pdf

Our house is a little bit unconventional, its an old barn, the kitchen is upstairs and access to the eves is direct from this floor - no ladders etc. Lugging 40kg up one of those loft ladders would not be fun, but noted about the weight. 250kg feels like its quite a lot - that being said we have a solid granite kitchen worktop in the middle of the kitchen which is about 3x3 metres. I suspect this must weigh something along those lines!

Also check out the warrant on the 5000 as against the 2000, 3000.

nowty wrote: ↑Thu Jul 14, 2022 6:22 pm The "Victron MultiPlus-II 5000VA" has a battery charging facility of only 70A circa 3.5kW

The "Quattro 48/8000" has a battery charging facility of 110A circa 5.5kW

Therefore both won't charge at a rate of 7kW as you want but in any case you wont be able to exceed about 100A 5kW with the standard cables unless you parallel up two stacks.

This link gives you some info about using the Pylontechs with the Victron kit including how to parallel up two battery stacks.
https://www.victronenergy.com/live/batt ... export_pdf

This is incredibly informative, thank you.

Do you know if there is a Victron product that will be able to pump in my 7KW. Maybe this is folly, but the way I saw it was if I can pull in a max of 7KW on a 32amp connection, I may as well do this. However if it increases complexity perhaps I should rethink it.

When you say 'with the standard cables' can I just upgrade the cables, or does this create a new host of issues (e.g. connectors are custom or something- sorry, I do not know which cables you are referring to)

But it certainly feels that the Victron MultiPlus-II 5000VA does not fit the bill, I had a look at the 10000VA version of the MultiPlus-II, and think i've worked out that would give me 140a which should be about 6.7KW of power, thats close enough for me I think - am I right in that assumption?

dazza666 wrote: ↑Fri Jul 15, 2022 11:18 am

nowty wrote: ↑Thu Jul 14, 2022 6:22 pm The "Victron MultiPlus-II 5000VA" has a battery charging facility of only 70A circa 3.5kW

The "Quattro 48/8000" has a battery charging facility of 110A circa 5.5kW

Therefore both won't charge at a rate of 7kW as you want but in any case you wont be able to exceed about 100A 5kW with the standard cables unless you parallel up two stacks.

This link gives you some info about using the Pylontechs with the Victron kit including how to parallel up two battery stacks.
https://www.victronenergy.com/live/batt ... export_pdf

This is incredibly informative, thank you.

Do you know if there is a Victron product that will be able to pump in my 7KW. Maybe this is folly, but the way I saw it was if I can pull in a max of 7KW on a 32amp connection, I may as well do this. However if it increases complexity perhaps I should rethink it.

When you say 'with the standard cables' can I just upgrade the cables, or does this create a new host of issues (e.g. connectors are custom or something- sorry, I do not know which cables you are referring to)

But it certainly feels that the Victron MultiPlus-II 5000VA does not fit the bill, I had a look at the 10000VA version of the MultiPlus-II, and think i've worked out that would give me 140a which should be about 6.7KW of power, thats close enough for me I think - am I right in that assumption?

I am talking about the 25mm cables that connect to the Pylontech batteries and Its not just the cables, its the connectors on the batteries too, so you need to parallel up the battery stacks to exceed 100A. See section 7 of that document I linked.

There is also the issue of DNO permission with a grid tie battery inverter so big. The rules are more straight forward with a smaller one not exceeding 3.68kW. The battery inverter will also require require to be hardwired into its own dedicated electrical circuit.

So if your not sure what your doing, you might better off starting with a cheap straight forward smaller one like a Sofar ME300SP.

__

Welcome Dazza.

What rates are you paying for your electricity? When I did the calcs earlier this year it was worth storing free solar in batteries but not worth time-shifting because the difference did not cover the depreciation on the batteries themselves.

There is a lot of Victron information to be gleaned by browsing the Q & A here: https://community.victronenergy.com/index.html.

The MultiPlus 5kVa has definitely got UK type approval, but worth checking if the Quattro 8kVA has, your DNO will need to see that too.