Solar PV battery options

DrPhilG · 05-03-2021 1:18pm #1

I figured it might be an idea to have a specific thread for this topic. Lots of us have home solar with batteries attached, usually GivEnergy, Pylontech etc usually in 2.4/4.8kWh levels.

Given the cost of batteries and the pending feed in tariff, its debatable whether these batteries will continue to make financial sense, (or if they ever did).

However there is essentially a separate market for the enthusiasts, to have large scale battery storage, 10kWh and beyond.

I thought it would be useful to have a thread for this area specifically, as it is essentially a different topic from the general Solar quotes thread.

DrPhilG · 05-03-2021 1:18pm

Some info copied from other threads:

samdeluxjones wrote: »

https://www.bsl-battery.com/powerwalls.html This crowd doing 10kW powerwall for €1770 + €250 shipping.

Anyone use them?

graememk wrote: »

to work out the kwh, its Nominal Voltage[3.2] x Capacity [200] x Number of cells [8] = 5.12kWh

Normally you need 15 or 16 cells for a 48V system that most inverters run on.

What sort of setup do you currently have?

championc wrote: »

If you searched with the word CALB, you cannot have got the link you gave here.

Here is the link and the proper cells

€ 1.389,00 30%OFF | NEW 16PCS CALB 3.2v 200Ah LiFePO4 Rechargeable Battery brand new 200AH 24V 48V 200AH Lithium iron Phosphate Packs Solar Battery
https://a.aliexpress.com/_mtLHTeb

gomamochi1 wrote: »

Is it possible to mix a 5kw pylontech system with these 10kw aliexpress batteries or do I need an independent bms for the ali batteries prior to the hybrid inverter? Thanks

championc wrote: »

Theoritically you could although you must remember that Pylontech use a 15s setup in their batteries, so you would only need 15 AliExpress cells and a 15s BMS

HOWEVER, while the inverters will "talk" directly to the Pylontech BMS, they can't "talk" to the AliExpress cells, But the two sets in parallel may work once you then set the Pylontechs to have a capacity of about 15kW. The power should equally be drawn off both sets and in the same way, charge both sets.

So the important part is that all cells must be of the same battery chemistry and the same number of cells per string.

DrPhilG wrote: »

That was my next question, presumably connecting any unsupported batteries, whether DIY EV cells, or cheap import Chinese cells, wouldn't be supported by the inverter companies and therefore would technically invalidate the warranty?

graememk wrote: »

No different to lead acid, as long as you operate within specifications it's fine.

You'd be far more likely to hurt the batteries than the inverter, if you put incorrect settings in.

DrPhilG · 05-03-2021 1:26pm

I'm interested in expanding to 20-30kWh in the long run, and then doubling my panels to 12.5kWp.

As I see it there are 3 options currently:

1 - Leaf cells. I can get a friend's 9kWh pack plus full BMS for a bit under €2.5k. I could then add another cars worth of batteries for around the same price, which would add 15kWh and maybe more depending on the SOH of the battery. That equates to a price of around €160/kWh plus a little extra for installation as I would get a pro to finish the hook up.

2 - AliExpress LiFePo4 cells. A know quite a few here have bought these. As I understand it, the pack is 10kWh but around 8kWh usable, and lands here for about €1400. That's about €175/kWh, but do you then need to add more kit, BMS, balancing etc?

3 - BSL-Battery.com. Linked on the other thread, they seem a bit more polished than the AliExpress stuff, and I think they come with inbuilt BMS etc. More expensive, I think someone got a quote of €2k delivered and cleared of customs. But I think that's a usable 10kWh, and no extra kit required.

graememk · 05-03-2021 2:31pm

All the batteries you mentioned is raw capacity, as you only want to discharge to 80% ish

That's why we say it's only about 8kwh on the CALB cells

Currently my inverter does most of the bms duties, and then I have a passive cell balancer keeping each cell balanced.

Same with the pylontech, it's raw capacity they quote

samdeluxjones · 05-03-2021 3:00pm

samdeluxjones wrote: »

https://www.bsl-battery.com/powerwalls.html This crowd doing 10kW powerwall for €1770 + €250 shipping.

Orders of 10 or more and they will pay for shipping.

DrPhilG · 05-03-2021 3:54pm

samdeluxjones wrote: »

Orders of 10 or more and they will pay for shipping.

Boardsie Groupon?

DrPhilG · 05-03-2021 3:57pm

graememk wrote: »

All the batteries you mentioned is raw capacity, as you only want to discharge to 80% ish

That's why we say it's only about 8kwh on the CALB cells

Currently my inverter does most of the bms duties, and then I have a passive cell balancer keeping each cell balanced.

Same with the pylontech, it's raw capacity they quote

Thanks.

I had thought of doing the same, letting the Solis manage the BMS issues. But then I read this:

"The inbuilt battery management system manages the overall voltage of the 48v battery. It does not manage the modules within the battery which is the most important part of the BMS. If a single cell has resistance issues and overcharges it can cause a fire whereas the overall voltage of the entire battery would not go over its inverter limits"

And it made me think twice.

Then again the LiFePo4 batteries claim that there is no fire risk, so would that mean that a balancer would be the only thing needed?

I'd been looking at relocating batteries to the garage as I wouldn't fancy a potential fire risk in the attic above my bedroom lol.

Are the LiFePo4 really completely safe on that front?

DrPhilG · 05-03-2021 4:02pm

samdeluxjones wrote: »

Orders of 10 or more and they will pay for shipping.

I'm in Donegal, so I've asked them for a delivery estimate to NI as well as to ROI. God knows how that would work, maybe worse. But might as well get the option.

Definitely could look into a bit of haggling if there were a number of people looking at it.

sebdavis · 05-03-2021 4:56pm

The BSL battery would be something I would interested in as it would seem more plug & play than buying in from Aliexpress? or am I wrong

DrPhilG · 05-03-2021 5:03pm

sebdavis wrote: »

The BSL battery would be something I would interested in as it would seem more plug & play than buying in from Aliexpress? or am I wrong

I don't know to be honest, at least 2 if not 3 folk here have the AliExpress batteries.

lightson · 05-03-2021 5:24pm

I ordered as a test to build first battey which I would use for van work. b4 investing in larger cells for house about 4 weeks ago.

4pcs 3.2V 100Ah LiFePO4 battery pack Lithium iron phospha.

I just chased them up and was told they failed security check and to open a dispute to get refund.

Think they never left china! wondering if anyone had similar problem or what sellers people have used and they have got to Ireland. bit shocked they didn't even get out of china and no idea what failed security check means?

https://www.aliexpress.com/item/1005001651207341.html?spm=a2g0s.9042311.0.0.27424c4dYg7KX5

keen to order some more as I have loads of other bits on way in post from China.

unkel · 05-03-2021 5:42pm

DrPhilG wrote: »

1 - Leaf cells. I can get a friend's 9kWh pack plus full BMS for a bit under €2.5k

Your "friend" is charging you quite a lot for that, is his paid time to build it for you included?

Leaf packs (24kWh minus degradation) go for about €1500 whole, so say about €110/kWh usable so a bit cheaper than CALB cells (€130/kWh), but the latter are brand new, much safer, not a hassle to get at and super easy to combine into a pack.

unkel · 05-03-2021 5:52pm

lightson wrote: »

I ordered as a test to build first battey which I would use for van work. b4 investing in larger cells for house about 4 weeks ago.

4pcs 3.2V 100Ah LiFePO4 battery pack Lithium iron phospha.

I just chased them up and was told they failed security check and to open a dispute to get refund.

Major problems getting these out of China for all sorts of reasons. I've had numerous orders cancelled on me, failed to ship, etc. with all sorts of excuses or lack of any communication. You'll get your money back though. Eventually. AliExpress customer service is no help at all though.

Best order from a reputable seller with loads of sales who preferably have a European distribution centre and who guarantee all taxes are pre-paid (otherwise it is likely you will get a nasty surprise of 23% VAT, plus import duty and admin clearing charges)

DrPhilG · 05-03-2021 6:14pm

unkel wrote: »

Your "friend" is charging you quite a lot for that, is his paid time to build it for you included?

That includes the pack, cabinet, all connections, and a brand new Batrium BMS which costs about €800 by itself.

unkel wrote: »

Leaf packs (24kWh minus degradation) go for about €1500 whole

Do they? Cheapest I've found was £2k sterling.

unkel · 05-03-2021 7:00pm

Batrium BMS are top notch.

Not sure about the wisdom of sticking an €800 BMS on a €750 battery though. I'd pick a €50 Daly BMS and chances are your pay back time will be half. These are fairly competent yokes. Batrium had its day back when batteries were very expensive and it made sense to invest heavily to protect them.

DrPhilG · 05-03-2021 7:03pm

unkel wrote: »

Not sure about the wisdom of sticking an €800 BMS on a €750 battery though.

It wouldn't be a €750 battery if I had 30kWh worth. And if the Leaf cells can be a fire risk, I wouldn't cheap out on a BMS.

Also these BSL-battery crowd seem interesting, if indeed the LiFePo4 batteries aren't a fire risk.

unkel · 05-03-2021 7:22pm

DrPhilG wrote: »

It wouldn't be a €750 battery if I had 30kWh worth.

I thought you said 9kWh?

Obviously a €3000 battery should get different considerations for a BMS than a €750 battery.

lightson · 05-03-2021 7:32pm

unkel wrote: »

Major problems getting these out of China for all sorts of reasons. I've had numerous orders cancelled on me, failed to ship, etc. with all sorts of excuses or lack of any communication. You'll get your money back though. Eventually. AliExpress customer service is no help at all though.

Best order from a reputable seller with loads of sales who preferably have a European distribution centre and who guarantee all taxes are pre-paid (otherwise it is likely you will get a nasty surprise of 23% VAT, plus import duty and admin clearing charges)

OK thanks

But I guess people are having success

ill try again so

DrPhilG · 05-03-2021 8:15pm

unkel wrote: »

I thought you said 9kWh?

Tut tut, pay attention young man!

DrPhilG wrote: »

I'm interested in expanding to 20-30kWh in the long run, and then doubling my panels to 12.5kWp.

unkel · 05-03-2021 8:26pm

DrPhilG wrote: »

Tut tut, pay attention young man!

Eh yeah, you can't just mix and match batteries and add to your existing ones whenever you feel like it.

And if a 9kWh pack based on degraded Leaf batteries costs you €2.5k I guess a 30kWh newish Leaf pack will cost you a good €7k to setup. That will never ever pay for itself man, don't kid yourself again with overly optimistic figures or figures that can even be proven to be technically impossible.

DrPhilG · 05-03-2021 9:17pm

unkel wrote: »

Eh yeah, you can't just mix and match batteries and add to your existing ones whenever you feel like it.

And if a 9kWh pack based on degraded Leaf batteries costs you €2.5k I guess a 30kWh newish Leaf pack will cost you a good €7k to setup. That will never ever pay for itself man.

Eh yeah, like I said, pay attention...

* I'm not paying €2.5k for a 9kWh battery
(I'm paying, if I went ahead, €2.5k for a 9kWh battery already stripped and built, along with a Batrium BMS. Cut the BMS out of it as you suggested and the pack is €1.7k.)

* I'm not buying a 30kWh Leaf pack
(I would be buying a 24kWh pack of the same chemistry as the original one. You already acknowledged this when you said I'd pay €1500 for a 24kWh so why are you now changing to a 30?)

* I'm not mixing and matching batteries
(see above)

* payback time is not the priority

unkel wrote: »

don't kid yourself again with overly optimistic figures

Now that's just rude. I was hoping that this thread would be a useful resource for those interested in various large battery options, not for you to have a jab at me over past disagreements.

Let's keep on topic?

Plus the Leaf cell battery is one option. I started this thread in order to discuss the others.

sebdavis · 05-03-2021 9:48pm

Back on topic. So I have 2.6kWh. Now really I would want at least 10kWh along with the 2kWh. My understanding is my 5kW invertor can support more. I have gone back to my supplier but as mentioned it was 2k for another 2kWh and I think 4k for a 4kWh.

If I could get 10kWh for 2k then I would be very happy.
In my limited knowledge I thought I could just buy more batteries and hook them up, but from what people are saying I will need BMS etc.

Has anyone asked if the BSL battery setup can just hook up? If not I wil email and post info

DrPhilG · 05-03-2021 9:53pm

I've sent an initial enquiry too, I'll report back.

graememk · 06-03-2021 12:13am

sebdavis wrote: »

Back on topic. So I have 2.6kWh. Now really I would want at least 10kWh along with the 2kWh. My understanding is my 5kW invertor can support more. I have gone back to my supplier but as mentioned it was 2k for another 2kWh and I think 4k for a 4kWh.

If I could get 10kWh for 2k then I would be very happy.
In my limited knowledge I thought I could just buy more batteries and hook them up, but from what people are saying I will need BMS etc.

Has anyone asked if the BSL battery setup can just hook up? If not I wil email and post info

There doesnt seem to be a standard bms communication protocol. For any of the inverters!

So if the inverter is looking to chat to a bms and dont follow the same protocol, Nothing will happen.

With my setup, the ME3000, in the default profile, it doesnt look for a bms. it just charges and discharges according to its own rules.
the SOC can sometimes get out of whack depending on where it is on the scale and current settings.

mp3guy · 06-03-2021 12:30am

graememk wrote: »

There doesnt seem to be a standard bms communication protocol. For any of the inverters!

So if the inverter is looking to chat to a bms and dont follow the same protocol, Nothing will happen.

With my setup, the ME3000, in the default profile, it doesnt look for a bms. it just charges and discharges according to its own rules.
the SOC can sometimes get out of whack depending on where it is on the scale and current settings.

I think this is the key message here, there's no common BMS/Inverter protocol, even if they happen to use CANbus.

DrPhilG · 06-03-2021 9:33am

mp3guy wrote: »

I think this is the key message here, there's no common BMS/Inverter protocol, even if they happen to use CANbus.

That's what attracts me to the BSL-battery crowd. They seem to have a lot of support and advice available before you shell out.

sebdavis · 06-03-2021 9:43am

DrPhilG wrote: »

That's what attracts me to the BSL-battery crowd. They seem to have a lot of support and advice available before you shell out.

I am a simple man, some might say very simple :-)
Some items I have no issues with trying to do a solo job and 9.5 times out of 10 I am successful but on the PV System if I can pay a few extra quid so it is easier to hook up great

Or even better if I can pay someone to do it for me. But I am not paying 2k for 2kWh. Complete rip off

DrPhilG · 06-03-2021 10:29am

sebdavis wrote: »

I am a simple man, some might say very simple :-)
Some items I have no issues with trying to do a solo job and 9.5 times out of 10 I am successful but on the PV System if I can pay a few extra quid so it is easier to hook up great

Or even better if I can pay someone to do it for me. But I am not paying 2k for 2kWh. Complete rip off

Similar position to me then lol.

The standard options around here are nuts. €1k seems the norm for a single 2.4kWh battery from the usual suppliers like the PylonTech that I have currently.

I know it might be a bit cheaper going the Leaf cell route, but it's also a lot more hands on and potentially a fire risk if its not done right.

Same with the cheaper LiFePo4 batteries on AliExpress. Bit cheaper, but still a bit of DIY involved.

The BSL batteries seem to be basically the best of both worlds. The ease of use of Pylontech etc, but with the cheap Chinese pricing.

samdeluxjones · 06-03-2021 1:11pm

Quote BLS Powerwall.jpg

The e-mail domain is not same as website domain. sales07@bullsbattery.com

https://www.bullsbattery.com/

but seems to be same company as BLS as both located at the same address.

unkel · 06-03-2021 1:18pm

DrPhilG wrote: »

Now that's just rude. I was hoping that this thread would be a useful resource for those interested in various large battery options

Some of us have looked into this stuff for years on renewable forums, etc. and have done our own home attached battery installs and our experience might help people who want to do the same to prevent them from making mistakes or from wasting money

I'm not the most diplomatic in expressing myself but if you can't take any criticism of the plans that you have (that are wasteful in my opinion), maybe you should just go ahead and not ask people's opinions...

DrPhilG · 06-03-2021 1:31pm

unkel wrote: »

Some of us have looked into this stuff for years on renewable forums, etc. and have done our own home attached battery installs and our experience might help people who want to do the same to prevent them from making mistakes or from wasting money

Precisely why I started this thread. Because the likes of yourself, mp3guy, championc and others have a wealth of experience in this field.

unkel wrote: »

I'm not the most diplomatic in expressing myself but if you can't take any criticism of the plans that you have (that are wasteful in my opinion), maybe you should just go ahead and not ask people's opinions...

I have no problem taking criticism and I admit to getting my wires crossed entirely in the previous "annual savings" discussion. Constructive criticism is the most likely thing to help in getting the right solution.

But you didn't just criticise my plans, you misunderstood them, jumped to conclusions, criticised my "friend", then had a dig at me over a previous discussion. You seem to be taking/making this very personal and I'm not sure why.

It was simply uncalled for.

However this thread is not just my plans, there are others here who are interested in the same thing so I don't see the point in derailing the whole thing just because you think I'm an eejit.

unkel · 06-03-2021 2:06pm

DrPhilG wrote: »

But you didn't just criticise my plans, you misunderstood them, jumped to conclusions

Yeah your digs there about me having to get with the program didn't help. It was you who talked about a 9kWh setup and then all of a sudden 30kWh. As if you can just change your battery or add to it. You can't. I had to force myself not to use a rolleyes there but instead use a more civil answer

For someone using this forum as a vehicle for learning and for extracting help and advice from others, you should really tone down your attitude or there won't be many people left willing to help you...

DrPhilG · 06-03-2021 3:09pm

For God sake man will you reel in the aggression for a second and realise that you're wrong here?

unkel wrote: »

Yeah your digs there about me having to get with the program didn't help.

If you're referring to the "pay attention" comment, that was clearly meant in humour. I thought the "tut tut young man" would have made that clear. However if that's what has kicked this off, I do apologise. The comment was meant in jest as I thought you had skimmed and misunderstood what I was talking about.

unkel wrote: »

It was you who talked about a 9kWh setup and then all of a sudden 30kWh.

No, I didn't. I made it crystal clear that I was looking at 9kWh initially, then adding another battery for about 15kWh usable, and later increasing to "20 to 30kWh". It is perfectly possible to add more Leaf cells to an existing DIY battery provided that they are the same chemistry and added in the correct numbers. I never at any point mentioned adding a 30kWh pack or mixing different types of battery.

unkel wrote: »

you should really tone down your attitude or there won't be many people left willing to help you...

What attitude? I have not been aggressive at all in this exchange. You have, and I have no idea why you're flying off the handle so much. The only attitude I've shown is in response to your belligerent attacks.

1 - You snidely accused my friend of overcharging me by ignoring the inclusion of the BMS in the price, and also (falsely imo) claiming that you can get a 24kWh pack for €1500.

2 - you then mocked me for wanting to add a 30kWh pack and mixing batteries, (which I had never suggested doing) and told me to "stop kidding myself".

I've tried repeatedly to steer this back on topic, but you've taken offence over something and are determined to be aggressive and put me in my place.

If so, consider me suitably berated. Now can we get back on topic?

DrPhilG · 06-03-2021 3:33pm

@samdeluxjones - how long did you wait for a response from China?

I've dropped them an email looking for some prices and some more info on compatability with my current system.

Their website says 24 hours so I'll report back once I hear.

samdeluxjones · 06-03-2021 5:23pm

DrPhilG wrote: »

@samdeluxjones - how long did you wait for a response from China?

I've dropped them an email looking for some prices and some more info on compatability with my current system.

Their website says 24 hours so I'll report back once I hear.

Almost instant on WhatsApp, they ask for your number on the inquiry page.

Scarlett's number is on the invoice you can WhatsApp her directly.Quote BLS Powerwall.jpg

samdeluxjones · 06-03-2021 5:42pm

BSL Cert.jpg

No idea how legit this is with EU standards.

They can't give me a straight answer on import duty or getting caught for VAT on customs clearance.

championc · 06-03-2021 5:48pm

DrPhilG wrote: »

I know it might be a bit cheaper going the Leaf cell route, but it's also a lot more hands on and potentially a fire risk if its not done right.

For starters, LiFePO4's are one of the safest compositions of battery. If a case ruptured in any way, you don't have the corrosive acid or Lead-Acid's nor the explosive possibilities of 18650's

But you have to understand where the danger comes from - which is either short circuits, inadequately sized wires and busbars or heat due to loose joints.

Therefore, I would trust my DIY POWERWALL every day of the week over a packaged up cell, where you have no knowledge of how well any connections were made, how adequate the cables used are for the charge and discharge, and how well the pack has been assembled.

With a DIY POWERWALL, you can overspec components to your hearts content. I bought a 100A BMS and I use 10m² DC cable. Both may well be overkill, but I felt worth the extra to be well within the limits of what I used.

I have also been very specific to recommend the CALB Cells rather than any of the Littokala cells which have inadequate (IMO) positive and negative terminals on each cell

graememk · 06-03-2021 6:25pm

samdeluxjones wrote: »

BSL Cert.jpg

No idea how legit this is with EU standards.

They can't give me a straight answer on import duty or getting caught for VAT on customs clearance.

It will be liable for 23% vat, not sure about import duties.

A 100kg box doesn't just slip past.

DrPhilG · 06-03-2021 7:23pm

graememk wrote: »

It will be liable for 23% vat, not sure about import duties.

A 100kg box doesn't just slip past.

Did you get the same cells as championc? Am I right in thinking that the prices you paid included import duties?

DrPhilG · 06-03-2021 7:30pm

championc wrote: »

For starters, LiFePO4's are one of the safest compositions of battery. If a case ruptured in any way, you don't have the corrosive acid or Lead-Acid's nor the explosive possibilities of 18650's

Thanks. This is the main thing turning me off the idea of a Leaf cell battery. With the best will in the world and a good BMS etc, there still remains the possibility of something going belly up and worst case scenario would be a serious fire/explosion.

LiFePo4 worse case scenario is presumably that it just stops working and you have a very expensive paperweight that you can't exactly take back to the shop. But that risk exists with any of these options.

championc wrote: »

I have also been very specific to recommend the CALB Cells rather than any of the Littokala cells which have inadequate (IMO) positive and negative terminals on each cell

Thanks again, I'll have another look at the stuff you have linked.

The BSL-battery site looked promising as a nicely packaged plug and play option, but the reality is that it's still a cheap Chinese battery shipped from the other side of the world with realistically no warranty or comeback.

Plus as samdeluxjones is now finding out, they are very vague on import duty, which means that the €2k estimate for a 10kWh battery would very quickly become €2.5k, compared to the €1.4k that you've paid including import.

graememk · 06-03-2021 8:12pm

DrPhilG wrote: »

Did you get the same cells as championc? Am I right in thinking that the prices you paid included import duties?

Yep they come via poland, and cleared there,

DrPhilG · 06-03-2021 8:18pm

graememk wrote: »

Yep they come via poland, and cleared there,

It's funny, being a mile from the border I'm used to getting stuff shipped to NI and collecting it there as its cheaper for postage.

Likely the complete opposite now due to Brexit.

graememk · 06-03-2021 8:58pm

For the Solis hybrid inverters, in the manual, look around pages 38-40, it gives all the custom settings for batteries on it.

The float is for lead acids, - ie you dont want to be doing that with the LiFePo4 - so current + time would be set to 0.

My experience is with the sofar, but that has a lot of similar settings, Mx charging voltage, minimum voltage, etc.

The last 2 "full and empty voltage" in the sofar is what is uses to calculate the SOC from the resting voltage, after an hour of sitting idle.
The calculation inbetween is sort of a dead reckoning. ie you tell it you have a 10kwh battery, it takes out 5kw, so it must be at 50%

If then you discharge to your minimum SOC... or hit a voltage limit. It goes into standby, after an hour it will read the voltage and then recalculate the SOC. The Me3000 calculates that more or less on a line from the empty voltage to the full voltage.

The curve for lifepo4 is very flat with 2 "flicks" at each end. So I've ignored them and with a lot of trial and error have a few different settings.
I can have the high % accurate, or the lower range accurate.

High comes at a cost of accuracy in the mid range(40-60%)- it tends to recalculate high

low end accuracy in the 30-50% which pushes the top end to be inaccurate - recalculates low

DrPhilG · 06-03-2021 9:18pm

Great details, thanks.

The Sofar is 3kw isn't it?

I'm planning to eventually increase to 12.5kWp across 2 inverters. Was looking at another Solis partly as its what I'm familiar with and partly to ensure that the 2 of them talk to each other for the purpose of export limitation.

championc · 06-03-2021 9:40pm

DrPhilG wrote: »

Thanks. This is the main thing turning me off the idea of a Leaf cell battery. With the best will in the world and a good BMS etc, there still remains the possibility of something going belly up and worst case scenario would be a serious fire/explosion.

LiFePo4 worse case scenario is presumably that it just stops working and you have a very expensive paperweight that you can't exactly take back to the shop. But that risk exists with any of these options.

I expect the leaf cells to de safe enough, but while voltages may look ok, the capacity might be degraded (and which is well documented for Leaf Gen 1's).

I assume that the Leaf setup needs a special BMS since the cells are 7.6v in 7s configuration. With the AliExpress cells, you simply buy a standard off the shelf 15s or 16s LiFePO4 BMS. The only thing I had to configure was the Capacity and the Low Temp Cutoff level. I bought the HEYO, but most buy the DALY.

Once the BMS is correctly configured and working, that will stop damage to the cells. The only thing, imo, that will leave you with a paperweight is simply a dud cell.

Just to clarify, I knew nothing about Solar this time 2 years ago. I know how to use a multimeter, spanners and a drill. Remember, the voltage is still only 48v DC, so it's all quite safe. Sometimes being inexperienced makes you pay more attention to what you are doing.

championc · 06-03-2021 11:17pm

For those seeing this thread for the first time, here are the AliExpress "CALB 200A LiFePO4" Cells -

This is how they would be connected to a Solis (or any other) inverter, and here is how the BMS is wired. This diagram is made up from a photograph of my ACTUAL Batteries, in place (you can see the tops of the row of Lead-Acid's below them). I made a frams for the Lead-Acids with Unistrut

[/QUOTE]

€ 1.389,00 30%OFF | NEW 16PCS CALB 3.2v 200Ah LiFePO4 Rechargeable Battery brand new 200AH 24V 48V 200AH Lithium iron Phosphate Packs Solar Battery
https://a.aliexpress.com/_mtLHTeb

sebdavis · 06-03-2021 11:31pm

championc wrote: »

For those seeing this thread for the first time, here are the AliExpress "CALB 200A LiFePO4" Cells -

This is how they would be connected to a Solis (or any other) inverter, and here is how the BMS is wired. This diagram is made up from a photograph of my ACTUAL Batteries, in place (you can see the tops of the row of Lead-Acid's below them). I made a frams for the Lead-Acids with Unistrut

€ 1.389,00 30%OFF | NEW 16PCS CALB 3.2v 200Ah LiFePO4 Rechargeable Battery brand new 200AH 24V 48V 200AH Lithium iron Phosphate Packs Solar Battery
https://a.aliexpress.com/_mtLHTeb

Which provides 10kWh?

DrPhilG · 06-03-2021 11:45pm

championc wrote: »

With the AliExpress cells, you simply buy a standard off the shelf 15s or 16s LiFePO4 BMS. The only thing I had to configure was the Capacity and the Low Temp Cutoff level. I bought the HEYO, but most buy the DALY.

So the inbuilt BMS of the inverter isn't sufficient?
The HEYO isn't that much more pricey than the DALY anyway.

Ps I notice there's a discount voucher for €17 off a single pack, and €51 off if buying 2.

Think I'd stay at 1 for now though. Would be different if I stood to save a lot on shipping but the shipping cost is inclusive anyway.

championc · 07-03-2021 12:21am

sebdavis wrote: »

Which provides 10kWh?

3.2v x 16 x 200A = 10240w

championc · 07-03-2021 12:25am

DrPhilG wrote: »

So the inbuilt BMS of the inverter isn't sufficient?

There is NO inbuilt BMS in any inverter. The Pylontech sends the details to the Inverter over the comms cable link. If this cable is disconnected or miswired, it simply will not work

graememk · 07-03-2021 12:28am

DrPhilG wrote: »

So the inbuilt BMS of the inverter isn't sufficient?
The HEYO isn't that much more pricey than the DALY anyway.

Ps I notice there's a discount voucher for €17 off a single pack, and €51 off if buying 2.

Think I'd stay at 1 for now though. Would be different if I stood to save a lot on shipping but the shipping cost is inclusive anyway.

Inverter cant keep the pack balanced.

Advantage of the Heyo is the low temp cutoff and individual cell monitoring.

I'm currently using just a passive balancer https://www.aliexpress.com/item/1005001356613723.html?spm=a2g0s.9042311.0.0.65fe4c4dretD5X

I check each cell with a multimeter every so often too just to be sure,

With all BMS's make sure you have it wired up correctly, 1 wrong wire can fry it.

Running the math, and knowing pylontech is a 15S (15 cells in series)

a 2.4kwh battery uses 50ah cells.

The above cells are 200ah.

A charge/discharge rate of 1C on a 50 ah battery is 50Amps
so the pylon tech is limited at 0.5 c on the charge/discharge.

I think on the 5kw inverters they can pull 5kw from the batteries.
with a 16S, 5kw, is 97 amps from the battery, 16mm2 cable will be the minimum.

so on a 200ah pack, that is still only 0.5 c.

a Plus with the bare cells, you could drop in another pack in parallel without any complications, just a change in settings.

Solar PV battery options

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