UK - About to purchase LiFePO4 cells for home battery + Inverter/BMS advice

[cjdell]

Hello, I'm at newb at this but have lurked on this forum for a little while. Thanks to advice from "Ray Builds Cool Stuff" and others on this forum I've asked for a quote from Jenny Wu (using email jennywu896@gmail.com) for 16 x 100Ah LiFePO4 cells. She has quoted $994 (£860) which seems reasonable to build a roughly 5kWh pack.

I'd prefer to buy from UK stock but this doesn't seem possible at the moment. I am very fearful of being ripped off based on other's prior bad experiences with buying direct from China. I just want to check that we're all still happy with Jenny?

The other thing would be the inverter / BMS combination. I am limited in what I can find but it seems like this Growatt inverter is suitable and available in the UK:

Growatt SPF5000 ES 5KW 48V Off Grid Solar Inverter In Parallel 220VAC MPPT+ Wifi | eBay

Growatt SPF5000 ES 5000W 48V Battery Off Grid Solar Inverter Pure Sine Wave 220VAC MPPT With WIFI Module. SPF5000 ES. 1x Growatt SPF5000 ES 5000W Solar Inverter. - Rated power 5KW, power factor 1, WIFI/ GPRS remote monitoring (optional).

www.ebay.co.uk

It must be off-grid (I want emergency power) but it will be grid attached most of the time.
It must be controllable. I want to schedule charge off-peak nighttime and discharge daytime. Even better if I can control export/import with a Raspberry Pi...
It want the option to add solar but I won't be doing that right away. For now I just want to time-shift electricity consumption and have the option for emergency power.

Assuming the Growatt is suitable, I need a smart BMS that can speak RS485 (or whatever) to the Growatt inverter and give me battery statistics (I am a nerd after all). There is a lot of confusion about protocols...

If this works out well for me I want to upgrade the pack (maybe 16S2P) or perhaps just building another one.

Appreciate any advice that can be offered. Also huge thanks to the documented experiences of people on this forum who have already helped me get this far.

Thanks

 

[jacekowski]

Is that price including shpping and taxes?
I've tried to get batteries from china twice this year and both times i've wasted 3 months waiting (luckily i got a refund).

 

[cjdell]

Is that price including shpping and taxes?
I've tried to get batteries from china twice this year and both times i've wasted 3 months waiting (luckily i got a refund).

Yes apparently it's all in. The only reason I'm considering this is thanks to the YouTuber "Ray Builds Cool Stuff". He has bought literally tonnes of cells from her and apparently others on this forum have too.

 

[Ron-ski]

I suggest you contact https://www.fogstar.co.uk/collections/lifepo4/products/eve-lifepo4-105ah-prismatic-cell if buy 16 they may well do a better price than advertised on their retail site, although it doesn't look like they will have stock until mid October.

I just bought 16 EVE 280AH grade A cells from them, all arrived in perfect condition and check out as A grade, well automotive grade.

 

[Steve_S]

An important point you were not clear on. IF going "Off Grid" you can still use Grid Power as a backup to charge your batteries, essentially it is viewed as nothing more than a battery Charger. But do NOT try to push power back to the grid lest you run afoul of hostile Power Co People and Govern-Mental types who relish in stupid bureaucracy.

 

[Ron-ski]

@Steve_S In the UK if your system is in anyway connected to the grid, even just to charge the batteries via the inverter then you need to inform the DNO, less than 3.68kw you can inform them after installation, if more then you need to apply for permission prior to installation.

 

[Steve_S]

@Steve_S In the UK if your system is in anyway connected to the grid, even just to charge the batteries via the inverter then you need to inform the DNO, less than 3.68kw you can inform them after installation, if more then you need to apply for permission prior to installation.

Goodness Gracious, even when used as a CHARGER - no different that a Charger for your 12V Car Battery. Bureaucracy gone wild... sheesh.

 

[Clifton]

I know you only want 100a batteries but when it's all done, BMS, wire, time, the 280a are a better value. Most only use 80% to keep the batteries happy. 5kw won't last long. My 16s 280a batteries run a 8000 btu window a/c, fridge, misc all night until the sun is back up. JK bms, mine doesn't comunicate, just set charge volts on inverter and use BMS as a safety.

 

[Steve_S]

the 280a are a better value.

I have to second this, the 280AH Cells are a better value all around and a good foundation cell to build upon, as most people usually quickly discover they've underestimated their usage typically within 6 months of installation. One must also consider "reserve" power because as well all know, "Stuff Happens and hit's the fan", which these days seems to happen far more often than ever before.

Dang that Murphy Guy and his freakin Laws !

 

[Goboatingnow]

Goodness Gracious, even when used as a CHARGER - no different that a Charger for your 12V Car Battery. Bureaucracy gone wild... sheesh.

No this is only if the charger is part of a grid tied invertor

 

[Clifton]

Assuming the Growatt is suitable, I need a smart BMS that can speak RS485 (or whatever) to the Growatt inverter and give me battery statistics (I am a nerd after all). There is a lot of confusion about protocols...

If you go with the JK, standard is bluetooth. Once you get it going and know your batteries are pretty balanced and everything is "good", you don't really look at your bms. I used the EG inverters with the Watchpower wifi app. For battery info it only gives voltage and capacity but voltage is all I need to know. I manually set the charge bulk/float voltage and to grid/to battery voltage points. Them communicaton might be helpful but don't let it be a deal killer for you. The JK has an active balancer. My batteries were off and never top balanced, #7 was a problem. A month later and the voltages are nearly identical on all.

 

[Ron-ski]

Goodness Gracious, even when used as a CHARGER - no different that a Charger for your 12V Car Battery. Bureaucracy gone wild... sheesh.

As @Goboatingnow stated if you use a stand-alone charger, which cannot feed power back to the grid, like a car battery charger, then no you don't need to inform anybody.

But if you are using an inverter to charge the battery, and that inverter is connected to the grid, then the inverter can feed power back, regardless of whether you set it not to, if it has the ability then you have to inform the DNO.

I also went with 280ah cells, and my battery rack will have the ability to hold 4 batteries.

 

[drh]

As @Goboatingnow stated if you use a stand-alone charger, which cannot feed power back to the grid, like a car battery charger, then no you don't need to inform anybody.

But if you are using an inverter to charge the battery, and that inverter is connected to the grid, then the inverter can feed power back, regardless of whether you set it not to, if it has the ability then you have to inform the DNO.

I also went with 280ah cells, and my battery rack will have the ability to hold 4 batteries.

What about off-grid inverters (not hybrid) that don't feed back into the grid, merely use an AC Input for backup power?

 

[Ron-ski]

@drh I don't know the rules inside out, but if the inverter is capable of feeding out to the grid via its grid connection, then its notifiable, if its physically impossible due to design, then I presume it wouldn't be notifiable.

 

[drh]

@drh I don't know the rules inside out, but if the inverter is capable of feeding out to the grid via its grid connection, then its notifiable, if its physically impossible due to design, then I presume it wouldn't be notifiable.

That would be my assumption. Most Inverters made by Voltronic Power (like their own Axpert models and the likes of MPP Solar, EG4 versions etc) , have separate AC Input and AC Outputs. So if you're connecting the AC Output to a separated loads panel and only using the AC input for backup power, then there is no back feed to the grid.

 

[cjdell]

Thanks everyone for the replies so far. It's sounds like the Growatt inverter isn't a bad choice then as no one has called that out.

Just need to decide on the BMS. I was originally thinking Seplos as that has been confirmed to work with the Growatt, but now it seems the JK is the better one to go for. So the Growatt will happily use any 48V source as long as configured correctly?

As for getting 280Ah cells, yes I wanted to but this pushes the budget too far out. I plan on upgrading the system in the future. For now this will be a learning experience. Unless someone knows where I can buy cheap (but reliable) grade B cells?

 

[Clifton]

I know MPP has a 8048 max that is 240v too. I don't know if it is on par price wise with the Growatt. I bought from Amy through Docan, Jenny seems to get equal praise. To save a buck, you could order from them but ship from China and wait a little longer.

About budget, I was originally going to use one 1000w grid tie inverter with limiter and 3 or 4 panels but after a lot of reading on here, some hard thinking, more reading, math and using an Emporia for a while, I ended up with two 13kw spilt phase EG's, batteries, and 24 panels. It added a lot more time to get done though but I didn't want to do it twice as it's a lot of work doing the batteries and everything else when you have life going on.

Download the Growatt manual and look at the battery settings like you are programming it. It will make more sense.

This guy has a lot of informative vids this is on the JK

 

[drh]

Thanks everyone for the replies so far. It's sounds like the Growatt inverter isn't a bad choice then as no one has called that out.

Just need to decide on the BMS. I was originally thinking Seplos as that has been confirmed to work with the Growatt, but now it seems the JK is the better one to go for. So the Growatt will happily use any 48V source as long as configured correctly?

As for getting 280Ah cells, yes I wanted to but this pushes the budget too far out. I plan on upgrading the system in the future. For now this will be a learning experience. Unless someone knows where I can buy cheap (but reliable) grade B cells?

From what I've seen about that Growatt 5000ES in the US, the Growatt was a solid choice for a lot of users. The irony is, its a 240V inverter designed for the EU market but for some weird reason, Growatt distributors in the UK don't offer it, presumably because they are still set in their ways of providing grid-tied solutions
Some US guy's didn't like it because in order to do split phase and get 120V out of it (for the US), they had to add the auto transformers, again not something we need to worry about here in the UK. Its a totally ass-backwards situation LOL.

The MPP Solar Max range is quite appealing too, I was tempted by the 11kW

Not so much DIY, seen as cheating by some and more expensive than building your own bank of LiFePO4, you could consider one of these server rack batteries which will plug 'n' play with the Growatt or MPP Solar out-of the-box:

 

[drh]

......Oh and which ever way you go, a word of warning, prices are rising constantly. What with crippling fuels transportation costs, double digit inflation and August 2022 seeing a massive slump in the British Pound against the Dollar, all goods are costing a lot more to import!

 

[cjdell]

So has anyone figured out export/import control with the Growatt? I want to be able to tell the inverter when to charge the batteries and when to discharge and also be able to control how much charge is held in reserve. Is this even possible?

Thinking along the lines of a Raspberry Pi sending commands to the inverter.