Life and efficiency of Solar Home Batteries

[Bob Smith]

Hello,

I have been trying to find that the manufacturers specs regarding the degradation of the batteries over their life time (or at least once they reached the end of their warranty).

I've only found Sunsynk publishing that information as I mentioned it in another post. They mention SoC @Product End of Life 40%. I rang Sunsynk and to my surprise they confirmed that after 10 years the useable capacity will be 40%. I find this number terrible.
However, I could not find that information on any of other manufacturers specs (Growatter, Tesla, Solax or Pylontech for instance do not publish that information or at least it is not easy to find).

I have sent Growatt and Pylontech an email over a week ago and no answer.
I contacted Batteryfactory who replied for the pylontech
According to Pylontech lifetime is 15 years at which point it will start dropping to around 80% after 10 years it should still be 90%
However, when I asked where they go that information from, they send me a datasheet that does not mention it.

They also send me this link
https://www.solarquotes.com.au/blog/home-battery-testing-results/


Sure this is an Australian website and there could be some differences with how things are done or provided in the UK. Nonetheless, it is somehow scaring the lack of reliability of batteries. The webpage is very detailed and sends back to even more detailed test results. Be warned

This is the problem with "long life" products it is difficult to know how they will actually performed and by the time you reach that age, the technology would have changed completely.

Is there anyone out there with using home batteries for more than 5 years, What is your experience to date?


The article makes a very good point. At the end of the day regardless of the performance the installers/manufacturers are promising you a certain level of performance. It does not meet it, then action your rights and claim on the warranty. As long as they still exist and consequently selecting the right installer/manufacturer is more important than the performance of the battery itself.

What are your thought and experience?
Thank you

 

[johnb2713]

Hi Bob,

Attached is the specs of the EVE cells I'm using along with aging graphs. Temperature of operation is significant.

J

 

[Bob Smith]

Thanks a lot John. Documentation as I like them

Now, I can tell my installer that if he does not provide such curves, I take a different brand!
There is a huge difference between 25°C and 45°C. I thought of putting my batteries in the attic. Maybe best to find a place inside the house!!.

 

[johnb2713]

Mine are going outside in an insulated cabinet with small heater under them. The batteries themselves are going to be in a double wll MDF enclosure within the cabinet. Hopefully I can use effective temperature control with the small 25w heater to keep them at 25 deg C.

 

[Bob Smith]

Do you also had an air con to avoid the temperature to be higher than let's say 30°C in summer?

 

[johnb2713]

Do you also had an air con to avoid the temperature to be higher than let's say 30°C in summer?

I wont be doing that, the number of days at 30 and above are very few. If there were more I would consider either a small chiller unit (probably convert an old fridge or drinks cooler), or a peltier pump.

 

[Bob Smith]

Hi Bob,

Attached is the specs of the EVE cells I'm using along with aging graphs. Temperature of operation is significant.

J

Hi John
just noticed this are only 3.2V battery. I do not think they can really compare in term of aging to the 48V batteries that are used to store leccie from PV Panels.

I recall you are building your own battery. Does that mean you are going to put them in parallel to increase to the require voltage?

I am not as DIY as you. I visited their website but unfortunately I could not find any ready home battery like the pylontech for instance.

Thanks for letting me know about this brand but I'll have to pass.

 

[Ronski]

@Bob Smith Put 16 in series and you have a 48v battery which can store 13.4kWh of leccie from your PV panels

Use the 304Ah version and you get 14.6kWh

 

[johnb2713]

Hi John
just noticed this are only 3.2V battery. I do not think they can really compare in term of aging to the 48V batteries that are used to store leccie from PV Panels.

I recall you are building your own battery. Does that mean you are going to put them in parallel to increase to the require voltage?

I am not as DIY as you. I visited their website but unfortunately I could not find any ready home battery like the pylontech for instance.

Thanks for letting me know about this brand but I'll have to pass.

No, they go in series for many good reasons.

 

[johnb2713]

Hi John
just noticed this are only 3.2V battery. I do not think they can really compare in term of aging to the 48V batteries that are used to store leccie from PV Panels.

LOL oh dear Bob, there's no such thing as a 48v battery, they're all made up of 15 or 16 LifeP04 cells at 3.2v each. So the aging data I supplied is accurate and relevant. Even a car battery isn't 12v, its made up of 6 x 2v cells.

 

[Bob Smith]

LOL oh dear Bob, there's no such thing as a 48v battery, they're all made up of 15 or 16 LifeP04 cells at 3.2v each. So the aging data I supplied is accurate and relevant. Even a car battery isn't 12v, its made up of 6 x 2v cells.

Yep, I am no expert Thanks for baring with me

Thank you for the EVE datasheets. This is very informative. I wish other suppliers were providing similar data. Sunsynk write that SoC will be 40% after the product life. (I assume they mean 10y or 6000 cycles). Pylontech or Growatt have no information on their datasheets and either brand don't mention if their batteries are made up of EVE or else.

Panels manufacturers do provide information about the degradation over time (generally around 0.5% per year), why is that so hard for the batteries manufacturers.

PS:
I came across these videos and thought of you.

 

[johnb2713]

Yep, I am no expert Thanks for baring with me

Thank you for the EVE datasheets. This is very informative. I wish other suppliers were providing similar data. Sunsynk write that SoC will be 40% after the product life. (I assume they mean 10y or 6000 cycles). Pylontech or Growatt have no information on their datasheets and either brand don't mention if their batteries are made up of EVE or else.

Panels manufacturers do provide information about the degradation over time (generally around 0.5% per year), why is that so hard for the batteries manufacturers.

PS:
I came across these videos and thought of you.

Thank you, Ill have a look.

 

[binky]

Yep, I am no expert Thanks for baring with me

Thank you for the EVE datasheets. This is very informative. I wish other suppliers were providing similar data. Sunsynk write that SoC will be 40% after the product life. (I assume they mean 10y or 6000 cycles). Pylontech or Growatt have no information on their datasheets and either brand don't mention if their batteries are made up of EVE or else.

Panels manufacturers do provide information about the degradation over time (generally around 0.5% per year), why is that so hard for the batteries manufacturers.

PS:
I came across these videos and thought of you.

Every time I see stuff like that I can't help thinking home made bomb .
If I could locate the battery out in my garage I would build one myself, but I don't like the idea of a self build battery within my house unless I can find a large steel box to put it in.

 

[johnb2713]

Every time I see stuff like that I can't help thinking home made bomb .
If I could locate the battery out in my garage I would build one myself, but I don't like the idea of a self build battery within my house unless I can find a large steel box to put it in.

Do you think the manufacturers have some magical powers? At least if I make it myself I know that top quality cells have been used, I know it will be built properly, I will have full understanding of whats going on inside the box. Mine is going outside on a wall, if it wants to self combust it wount harm anything other than itself. The enclosure has temperature control keeping the temps above 20 deg C and temperature monitoring fed back to my Home Assistant system. If temperatures reach 30 deg C it will shut down by opening the mains contactor and shutting down the BMS. I am toying with idea of checking pressure across the packs, if any one of them starts swelling again it will be shut down. I dont know of any commercial product that has this level of safety.