diy solar

diy solar

This, or that, or wait, maybe that?

Lightning29

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Joined
May 9, 2024
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CO
Firstly, what a great resource this forum is, I’ve scrolled quite a bit and learned lots, thank you all who contribute!

My why and some details: I live in a mountain town in Colorado at around 8,500’, so plenty of sunshine here. I rent a house, so I’m not doing a full array here. I do plan on buying our own place somewhere in the country in the next year or so, where I would want a good off grid setup. In the event of a power grid failure I want to keep the fridge and 2 freezers going at a minimum. That’s the starting why that will grow into being off grid once we get our own place. I also don’t want to rely on a gasoline or propane generator and have to store the fuel, hence solar.

I’ll buy used solar panels semi locally. I’m thinking 750-1,000w total for this location. I’d like to just take over the breaker for the garage with solar as the 2 freezers are in there. If there’s power left to spare, great!

My question: AIO vs itemized system, and 12v, 24v, or 48v? We err on the ‘buy once cry once’ side of things and I’d like good components even if they aren’t the cheapest. I’m mechanically inclined, work in construction, but green with electrical. I’ve seen opinions that 12v is good till 3,000w, but I thought I’d go 24v to reduce wire size and cut amps in half. Then I read more and get the feeling some are of the opinion that if you go 24v you really just might as well go 48v right away.

I like the idea of being able to grow into it, but not sure if I need to go all out and start a small 48v system that can move to the future place and take on everything, or should I stay minimal and do a larger 12v system? Or 24v?
Future place would have workshop with welder etc.

Also AIO’s… I don’t mind building out an itemized system instead of an AIO, especially if that means it would help answer the voltage question in some way.

Was thinking LiTime batteries.

Thanks in advance!
 
With new solar panels being so low cost I would suggest not buying used unless they were practically free for the taking. Go 48vDC battery since you are likely to expand the loads you wish to power in the future. Since you are only going to be temporary at first going the component route for SCC and inverter/charger may be a better option initially though there are some decent low cost AIO's available.
 
Outback is high quality on and off-grid components. But expensive.

Buy a flexmax charge controller. The 60 and 80 versions are 12v to 48v. The 100 is 24v-48v. Buy that to charge your battery.

Buy four 12v lifepo4 batteries you can put in series or parallel.

Buy a cheap 12v inverter.

Throw the inverter away when you are ready to upgrade to a 48v system. Rewire the batteries from parallel to serial.

If you buy the flexmax off ebay, maybe when you upgrade, sell it on ebay and buy an AIO.

Note the startup amps you will need to run the freezers.
 
Great title for this post:
This, or that, or wait, maybe that?

Dre, creep to the mic like a phantom
 
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48v 100%

Just consider 1 Lifepower4 a minimum starting point for battery capacity. Then as big as the system grows, it will always be a helpful addition in parallel. I gave 1 Lifepower4 now paralleled to my DIY 304Ah pack.
 
48v 100%

Just consider 1 Lifepower4 a minimum starting point for battery capacity. Then as big as the system grows, it will always be a helpful addition in parallel. I gave 1 Lifepower4 now paralleled to my DIY 304Ah pack.
Rather one 48v battery vs 4 12v 100ah batteries? If I would get a CC that could handle 12v-48v and 80a then I could even start with 2 12v 100ah's and get 200ah's wired together, on 750w worth of panels. Am I missing something or would that not be more economical and allow a lower cost of entry but big growth in the future? Or is it super beneficial to have the same voltage batteries as what your system is instead of wired together batteries?
 
Rather one 48v battery vs 4 12v 100ah batteries?
Absolutely 1 48v battery super beneficial. The BMS must be able to see all cells at once to work well. 12v in series have a permanent disadvantage that has to be addressed with another balancer or manual balancing.

I know it's a financial hurdle, I was there too and I was stuck on it for months. But 1 Lifepower4 really is the only good minimum place to start and no less than that. I say Lifepower4 because I think they're the best value, but any other 100Ah 48v can be considered as well. I would not consider the Ecoworthy 48v 50Ah.

Will's Hand Truck build is probably the cheapest fastest way to get running, but if you plan to wire up a panel that's already 240v split phase then the 3k being 120v is a shortcoming to consider. It can be worked around if you have no 120v loads.
 
Rather one 48v battery vs 4 12v 100ah batteries? If I would get a CC that could handle 12v-48v and 80a then I could even start with 2 12v 100ah's and get 200ah's wired together, on 750w worth of panels.

DIY an 8 cell 24v lifepo4 battery. Get an 8-17 or 8-24 bms. You can buy more cells later to grow to 48v.
 
Seems like I'm the only one on this forum with this opinion, so feel free to ignore me, but don't DIY your battery, period. Unless you want to spend 3 months researching, buying parts, and tinkering. It's way more work than it looks, and way more work than most here are willing to admit. When you include the cost of your time, you're paying more for DIY batteries than finished batteries. After you build your first battery, it gets a lot faster, but still....

Just as 1 example, in my case, first I bought 2 Daly BMS because I saw Will testing one in his videos.
"Welp, @Will Prowse is testing one, so must be real good."
Then I realized Daly was no good and bought 3 JK-BMS because people seem to like those. Then I discover that I need communications between my inverter and battery and I should have bought a Seplos BMS. Right there I wasted $700 plus, not including my research time and now I have to list all my unwanted BMS's for sale. This is the nitty gritty that people on this forum forget to tell you about when you're just getting started and have no idea what you're doing.
 
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Seems like I'm the only one on this forum with this opinion, so feel free to ignore me, but don't DIY your battery, period. Unless you want to spend 3 months researching, buying parts, and tinkering. It's way more work than it looks, and way more work than most here are willing to admit.
3 months? It took me 6!
 
Meh, I would disagree but then I only build 12v and 24v batteries and don't care about communications. Since this is a hobby my time is my own so zero cost to me AND relieves boredom (boredom and I are NOT friends, I get dangerous) with something useable.

The tools are like any other tools, an investment that you'll use for years. I'd guesstimate as many batteries as I've built and as much as I've spent I'm already less than $20/battery so getting cheaper with every build.

Yes, the 100ah batteries are cheaper now to buy than build, but 280 or 304ah batteries are a SIGNIFICANT savings to DIY plus knowing I have a good BMS and wires is reassuring.

But that's my $0.02, YMMV.

Also, just to have an unpopular opinion, I'll never waste money on a JK again. My Daly's have ALL outperformed my JK's, and they're my #2 pick if JBD doesn't have what I want.
 
3 months? It took me 6!
Yeah exactly. Well, 3 months, if you don't count the 2 years my batteries spent sitting in their boxes unopened because I didn't have the time to do the project or I was waiting for one part or another.
 
I only build 12v and 24v batteries and don't care about communications
I didn't even know batteries communicated to inverters until after I had bought the wrong BMS's twice.
Since this is a hobby my time is my own so zero cost
Sure, if your time has a value of 0, or if this is a fun hobby to you, that changes things drastically.
The tools are like any other tools, an investment that you'll use for years.
Either that or you'll never use them again. Like I bought a pretty expensive (used) battery charger I'm probably only going to use twice. I spent hours custom cutting and putting ring terminals on about 60 pieces of thick expensive wire just to top balance my battery and I'll probably only use them twice as well. I bought a $145 crimper I probably won't use again after this project is done. If you're going to keep building batteries every couple years, maybe in 10 years your initial investment will pay off.

And he's absolutely right, after you build the first battery and make all your mistakes and learn what you're doing, then it gets much much faster and you can start building batteries pretty fast and cheaply. The question is, are you going to be doing that or not.
 
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Seems like I'm the only one on this forum with this opinion, so feel free to ignore me, but don't DIY your battery, period. Unless you want to spend 3 months researching, buying parts, and tinkering. It's way more work than it looks, and way more work than most here are willing to admit. When you include the cost of your time, you're paying more for DIY batteries than finished batteries. After you build your first battery, it gets a lot faster, but still....
Poster has a special case of wanting to start with a 12v system and grow to a 48v system. People raised the concern of keeping balanced 12v batteries in series. The easy solution is to build a battery and reconfigure.
 
Just because you had a bad experience....

I said it took me 3 months. @hwy17 just said it took him 6:
3 months? It took me 6!

When you say "easy" some people think of easy as like ordering a burger at McDonalds.
If something takes some folks 3-6 months, would you consider it easy?
"I just spent 6 months on an easy project" - Makes no sense, does it?
 
I said it took me 3 months. @hwy17 just said it took him 6:


When you say "easy" some people think of easy as like ordering a burger at McDonalds.
If something takes some folks 3-6 months, would you consider it easy?
"I just spent 6 months on an easy project" - Makes no sense, does it?
If you are DIY a solar power system, the additional work to DIY a battery is not much more. You back out the research part because that is required whether he builds or buys. Also by DIY, you learn a lot about how batteries integrate into the system. Plus, safety: proper wire sizing, class t fuse, etc.
 
the additional work to DIY a battery is not much more
You didn't answer my question, and 3-6 months is much more no matter how you slice it. Why do you want to minimize it or call it easy when it's not easy for the vast majority of the population?

But anyway, the OP can do whatever he wants, I've made my point. Good luck OP!
 
Aside from the time it takes to top balance the cells a 16 cell, 48 volt battery, it takes me a couple hours to assemble. Granted, I've built a few batteries in the last couple years but I have to say, your remarks are only going to dissuade people from doing the DIY approach and they aren't accurate as to building batteries.
 
"I just spent 6 months on an easy project" - Makes no sense, does it?
My Favorite Wife and I have a saying "That is/was an Easy Task", by which we mean it will (or has) eaten up way more time/effort/energy/resources than anyone could have imagined.
 
I certainly see the allure in building your own battery, and would kinda like to give it a try just for the learning experience. However, the system that's going to be running my house is all going to be COTS hardware (mostly from EG4), so it'll just work (yes, once I get the commissioning done and the bugs worked out). The DIY part (for me) is determining what modules I need and how they are mounted, interconnected, and operated, not what my BMS wiring looks like. I also don't build my own inverters, or circuit breakers, nor do I draw and insulate my own wire. 8*)

Everything's modular, it just depends what your modules are.
 
"Tack tack tack" is what my dad used to tell my mom when she described what she wanted and said it was easy. She had once said 'a little tack tack tack and it is done'....


Battery building is 'tack tack tack', but the difference is the time learning to do it right.

But, I agree unless your end goal is building large scale batteries it is best to buy pre-made batteries.
 
You didn't answer my question, and 3-6 months is much more no matter how you slice it. Why do you want to minimize it or call it easy when it's not easy for the vast majority of the population?

But anyway, the OP can do whatever he wants, I've made my point. Good luck OP!
Took me less than a month from when I ordered the parts to getting it working with my inverter. I only had time to play on weekends, and I took it slowly (measure twice, cut once). I would have spent at least 2 weeks installing a COTS battery (wire, fuses, switches, initial charge, building the rack to hold the battery, etc). Also integrated a generator and chargeverter during that month.

If you can install panels yourself, wire an inverter into the house yourself, it doesn't take much more to build a battery yourself.
 
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DIY an 8 cell 24v lifepo4 battery. Get an 8-17 or 8-24 bms. You can buy more cells later to grow to 48v.
Except mixing used cells and new cells might be a recipe for disaster (or at least suboptimal functioning)
 
Except mixing used cells and new cells might be a recipe for disaster (or at least suboptimal functioning)
Sub optimal 16 cell 48v, or throw away 8 cells? Even if you get 90% of the use of the additional 8 new cells, it is cheaper than buying 16 new.
 
Outback is high quality on and off-grid components. But expensive.

Buy a flexmax charge controller. The 60 and 80 versions are 12v to 48v. The 100 is 24v-48v. Buy that to charge your battery.

The FlexMax 60/80 are limited to 150 VOC, so the FlexMax 100 with 300 VOC is certainly a better choice.

The FlexMax 100 quite pricy for a single input MPPT solar inverter (See powerstore.com)

However the FlexMax 100 is AFCI detection compliant and provides Rapid Shutdown control (2017 NEC 690.12).
 
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