DIY battery or just go off the shelf?

[arfbarkyPrime]

So now that an attractive (to me) split phase solution has come out (EG4 6000XP) for a good price, I'm ready to add battery backup to my house. I currently have 39 Mage 230w panels grid tied with Enphase M190. I am in SE Michigan so for now, I'm not going to hook up any solar to the inverter since I don't want to go on the roof in the cold/snow and peel away 5-6 panels from the Enphase system.

Anyway, my question is: there are a million battery options! I am a skilled DIYer, so should I build up my own 48v batteries (looking to start with about 200AH), or should I not bother and get something off the shelf. For either option, what is the most economical? The inverter price I am fine with, but still, battery prices are hard to swallow! Thanks!

 

[Wjm1964]

Battery prices are dropping which is great but when you consider a DIY build there are many additional costs such as tools, wires, bms, power supply for top balancing etc which soon add up and as such I'd say buy a pre built unit to meet your demands. Added bonus is a warranty if you buy from a reputable company.

 

[400bird]

I realize this question is about batteries, and I don't have an answer there. I'd DIY, but I also wouldn't buy anything from Signature Solar/EG4.

Anyways, if you are planning to leave the Enphase micro inverters in place, that would mean AC coupling between them and the battery inverter.

Based on this older thread, AC coupling wasn't implemented yet. Also, most inverters max out at a 1:1 ratio for battery inverter to AC solar. You've got over 7,000 watts up there and are looking at a 6kW inverter. So, unless things have changed in the past year, I doubt that inverter is a good choice.

EG4 6000EX AC Coupling?

I notice in the manual for the 6000EX model that there might be an AC coupling option? Is anybody using this? Is it to AC Couple to another inverter, or to be AC Coupled to?

diysolarforum.com

 

[arfbarkyPrime]

I'm going to leave most of the Enphase connected they way it is. I'll have a subpanel on the other side of the inverter. In the spring I was planning on peeling off 5-7 solar panels, remove the Enphase inverters and run them as a string into the inverter.

I heard Signature Solar was bad, I was going to buy from Current Connected.

 

[hardtop]

I'm enjoying the DIY route. Even after all tool purchases, mistakes and shit purchases, I'm still way under a store bought battery like Battle Born. I didn't top balance so I'm surely going to hell so there is that and I saved by not buying a one-time-use power supply.

 

[arfbarkyPrime]

I'm enjoying the DIY route. Even after all tool purchases, mistakes and shit purchases, I'm still way under a store bought battery like Battle Born. I didn't top balance so I'm surely going to hell so there is that and I saved by not buying a one-time-use power supply.

What did you build, like with what cells and BMS and all that, and were did you get it? I'd enjoy doing it too ... but there's so much info it's hard to know where to start.

 

[Bob B]

Who is still building DIY batteries

Ok. There are plenty of discussions on UL ratings and cost comparisons of DIY vs prebuilt batteries. What I want to know is who is still doing DIY and the reasons you chose this approach. I will go first. At first it was the only thing going. Later it was for the challenge and satisfaction...

diysolarforum.com

 

[Quattrohead]

I realize this question is about batteries, and I don't have an answer there. I'd DIY, but I also wouldn't buy anything from Signature Solar/EG4.

I don't think this opinion is particularly helpful.
And he is asking about the 6000XP not the 6000EX.

 

[Quattrohead]

I enjoyed DIY batteries and the savings appeared to be considerable, but at the end of the day my home built wooden cases with open tops etc were woefully unprofessional. I have ended up rehousing all those cells in proper metal cases.
I am also under the impression that AC coupling will be coming for the 6000XP.

 

[hardtop]

What did you build, like with what cells and BMS and all that, and were did you get it? I'd enjoy doing it too ... but there's so much info it's hard to know where to start.

I built a 12V pack of EVE 304 cells. The BMS was JK and it was DOA. Then I bought a JDB and it cuts off 12V out sometimes after the charge is finishes so I have another JK on order. My only vendor recommendation so far would be to stay away from the 18650 battery store.

 

[featherlite]

stay away from the 18650 battery store.

Could you please expand and let us know the reasons why?

 

[400bird]

I don't think this opinion is particularly helpful.

That's fine, just making sure the OP is aware of the reputation Signature Solar has around these places. Entirely hit or miss and the misses seem to be really far from a good interaction.

And he is asking about the 6000XP not the 6000EX.

I'll I did was Google that inverter, saw nothing about AC coupling on the correct Signature Solar page. Then I clicked on the wrong forum link, good catch, thanks.

I enjoyed DIY batteries and the savings appeared to be considerable, but at the end of the day my home built wooden cases with open tops etc were woefully unprofessional. I have ended up rehousing all those cells in proper metal cases.

Diy with metal case is the way I went. I'm happy with my decision. I don't think it's the right decision for many.

I am also under the impression that AC coupling will be coming for the 6000XP.

My strongest recommendation is not to buy based on a future capability that may never happen, then you're stuck with something that doesn't have a feature you have the perception of having paid for. In their case, it wouldn't work for the application.

I'm going to leave most of the Enphase connected they way it is. I'll have a subpanel on the other side of the inverter.

What is "the other side"?
I'm guessing you're talking about a critical loads panel on the inverter output. Where will you connect the Enphase system? If you choose an inverter capable of AC coupling, you can put the Enphase output in the CLP or directly to an AC input of the inverter and charge the battery from AC and have your full Enphase system online and producing when the grid is down.

In the spring I was planning on peeling off 5-7 solar panels, remove the Enphase inverters and run them as a string into the inverter.

I like that plan.

I heard Signature Solar was bad, I was going to buy from Current Connected.

Is it worth pointing out that EG4 is basically the Signature Solar house brand that can also be purchased from other vendors?

 

[SignatureSolarJess]

I heard Signature Solar was bad

If you ever decide otherwise, you're welcome to reach out to me at engagement@signaturesolar.com and I can ensure you are taken care of!

 

[Alkaline]

My only vendor recommendation so far would be to stay away from the 18650 battery store.

So you are saying to with 18650 or do not, the way you worded is creating confusion.