DIY Power Wall

[Guille2212]

Hello, Im a beginner in this power wall thing, I would like to build one myself in order to store the energy produced by my panels but I don't have a clue on where to start this project. After some researches, I found that I could use a battery module instead of all the little batteries. Do you think that this one would suit: https://ebay.us/m/AjF6uU
Do you think that this option is good or it is too expensive ?
Thx

 

[paulie]

you need to read and/or search the forum. Personally I found the 18650 cell route too time consuming and whilst i have about 1500 cells in operation (24 volt system). I would personally choose lifepo 4 cells with a good bms if now starting from scratch. Depends how cheap and how much time you have. HB powerwall on You tube (Pete) is a good place to start if you want to re cycle 18650 cells. Best of British old chap. "La mejor de las suertes"

 

[OffGridInTheCity]

The battery you show is priced well (11.3kwh / 600 = 54Euro/kwh) but is 24s - meaning 24 LifePo4s in series which give a higher than normal operating voltage range of 48v low to 91.2v hi.

When I say 'higher than normal' it means that normal (best priced) equipment such as inverters or AIOs are more difficult to find so if you find something compatible, the savings in 'battery' may be lost due to higher priced equipment. This leads to customizing the battery to 16s (best number in series for normal, good priced, equipment). Customization means pulling out the individual cells or cutting things at 16s and rewiring - for example if you got 2 of these you could do 16s3p with some rewiring to get in the neighborhood of 22Kwh. The cost of cutting/rewiring/adding-BMS/building-shelving etc depends on you're personal situation and may also add to the cost.

As an alternative, especially for a newer DIY'er, here's an example of buying a reasonably priced 'kit' ($106/kwh) with 16Kwh that you can assemble as illustrated by a legitimate youtuber (@Lithium Solar one of the founders of this forum - e.g. @TheBatteries handle). There are other kits as well if you search a bit.

View: https://youtu.be/asdC9fT1aSM?si=vSG9ocVXaZCRQIuc

The customization depends on what level and kind DIY'ing you want to do.

No matter what route you go - the basics are to charge/discharge each cell to verify what you have. When buying an already together battery like you picture above you can try charge/discharge the overall battery with a BMS and see if you can get the cells balanced etc / all is good. But you need to settle on you're design - e.g. 16s or 24s as discussed above - and then get the matching equipment.

 

[Korishan]

I would recommend if you can financially is to get 2 units. Altho looks like they have only 1 available. They have a pretty decent amount of EV components, so ask if they have, or will have, another one.
Then, if you have 2 units, you could rewire the packs and get 3 batteries of 16s.

But ultimately I would go the route of OffGridInTheCity recommends with those boxes pretty much ready to go. Just don't get a unit that is already assembled as you will pay a fortune for shipping or they will have the sale price very high. Get the cells separate from the box to get the best deals.