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Trying to get ready for solar+battery install (heat pump asap)

I found a good contact for Nissan leaf cells, I've bought 70x1.6kwh packs, to run 10p7s as 48v 100kwh (they're 2s packs, so it's 10914s really)

Same guy supplied me with a bms, balancer, fuses, disconnect etc. etc.

Workshop where first solar install is going will be knocked down and re-built soon, batteries are going in there too

I'll probably have 3 phase installed, it's a very short run so it shouldn't cost too much

In the winter we'll probably have to charge overnight cheap rate


any info/recommendations/ideas about inverters?

I'd like to look around now and be ready

finding the right info feels like getting blood from a stone, which inverters support 48v batteries, which are 3 phase, which will work together with 1 battery but 3x single phase inverters... etc. etc.

Can you explain this bit, please?

I've bought 70x1.6kwh packs, to run 10p7s as 48v 100kwh (they're 2s packs, so it's 10914s really)

If you don't mind spending money the SMA Sunny Islands will cope with all of that. You can set them up as a 3 phase system, parallel up to 3 of them in a simple system, more if you complicate the system somewhat. They can be setup in various modes - stand alone with generator backup, grid tied with export, etc.

I have 2 Sunny Island 8s running in parallel with approximately 1500Ah of 48V LiFEPO4 batteries - 12kW continuous, 16kW for 30 minutes, 18kW for 5 minutes. 3 phase isn't needed for any reasonable household.

Loads include 2 induction hobs (notional 7.6kW each), 2 ASHPs an A2A mini split and a 7kW car charger.

Stinsy wrote: ↑Mon Feb 03, 2025 1:14 pm Can you explain this bit, please?

I've bought 70x1.6kwh packs, to run 10p7s as 48v 100kwh (they're 2s packs, so it's 10914s really)

I suspect he means 10p7s of packs which given each pack is 2s means 10p14s in terms of cells.

I see. That makes sense!

I believe LEAF cells are nominally 3.75V with a max charging Voltage of 4.2V. at 14s that multiplies to 52.5V and 58.8V. This is fine for low power levels eg 3.6kW, but once you get above 5kW the current levels start to get out of control. Therefore nowadays higher pack voltages are used.

Here is a typical 3-phase hybrid inverter: https://www.itstechnologies.shop/produc ... -inverter/

It is designed to work with battery packs between 120-800V. Therefore the original 96s 360V arrangement would work very well.

One article on multiple nverters that may be relevant (or slightly ott): https://www.victronenergy.com/live/_med ... ystems.pdf

Victron is regarded as very good kit, and very wel supported (I think SMA is also). Some of the other brands seem to have significant support issues - see various threads on this forum.

There is also a Victron article on configuring buses for multiple batteries multiple inverters etc. but I can't remember the name of so hopefully someone else can post a link to it.

OK found it: https://www.victronenergy.com/upload/do ... pdf-en.pdf

+1 for Victron, I have 3 running in parallel on single phase, 3 battery banks outputs linked together and each bank running JK BMS.

HML wrote: ↑Mon Feb 03, 2025 1:18 pm If you don't mind spending money the SMA Sunny Islands will cope with all of that. You can set them up as a 3 phase system, parallel up to 3 of them in a simple system, more if you complicate the system somewhat. They can be setup in various modes - stand alone with generator backup, grid tied with export, etc.
I have 2 Sunny Island 8s running in parallel with approximately 1500Ah of 48V LiFEPO4 batteries - 12kW continuous, 16kW for 30 minutes, 18kW for 5 minutes. 3 phase isn't needed for any reasonable household.
Loads include 2 induction hobs (notional 7.6kW each), 2 ASHPs an A2A mini split and a 7kW car charger.

oh I remember reading peoples posts about Sunny Islands years ago on the navitron forum...

do you have separate battery banks for each or one battery bank with both connected?

re: 3 phase, heat calcs say we need almost 30kw of heating - going to insulate the hell out of the place but the best I could possibly do (best windows, 300mmloft, 300mm underfloor, 300mm exterior wall insulation) only brought it down to 20kwh ish

add in one car charger for my gf right now, I assume a second one at some point for me, then in the future kids too (no kids yet!)

I intend to go crazy with the solar pv and add as much as possible

plus I've worked with 3 phase since I was a little kid helping my dad, more than happy to work with it etc.

Stinsy wrote: ↑Mon Feb 03, 2025 1:35 pm I see. That makes sense!
I believe LEAF cells are nominally 3.75V with a max charging Voltage of 4.2V. at 14s that multiplies to 52.5V and 58.8V. This is fine for low power levels eg 3.6kW, but once you get above 5kW the current levels start to get out of control. Therefore nowadays higher pack voltages are used.
Here is a typical 3-phase hybrid inverter: https://www.itstechnologies.shop/produc ... -inverter/
It is designed to work with battery packs between 120-800V. Therefore the original 96s 360V arrangement would work very well.

I'm a bit scared of high voltage DC... I'm a bit clumsy... had enough 240v shocks in my life, but high voltage dc your muscles tense up and you can't leave go.... probably best left to someone who's a bit more careful then I am :-o

Countrypaul wrote: ↑Mon Feb 03, 2025 2:13 pm One article on multiple nverters that may be relevant (or slightly ott): https://www.victronenergy.com/live/_med ... ystems.pdf
Victron is regarded as very good kit, and very wel supported (I think SMA is also). Some of the other brands seem to have significant support issues - see various threads on this forum.
There is also a Victron article on configuring buses for multiple batteries multiple inverters etc. but I can't remember the name of so hopefully someone else can post a link to it.
OK found it: https://www.victronenergy.com/upload/do ... pdf-en.pdf

oh that does look good, I was stuck on the idea of thinking one inverter to do battery and solar together, separating it out sounds much better