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Only a licensed electrician can perform permitted work. Otherwise, you're better off doing it yourself, easier to maintain the system if you fully understand how it works.
Gexpro has the best prices period (but they don't do installation). Online vendors have higher prices and expensive shipping (and still don't do installation).
Last I checked, all the "interesting" lithium technologies are only available through an installer, and there are few (if any) options for off-grid. For example, Tesla Powerwall runs at 350VDC, will probably work with a Morningstar HV controller, but now it's all custom ordered parts and expensive shipping.
Lithium ion phosphate: expensive, very low density; the footprint is easily 10x the size of other technologies, and has to be installed with a forklift.
Nickel-iron: yes, an Outback controller will drive these (with custom settings), but the batteries themselves are expensive, custom order, wait for shipping.
Outback NC batteries are available today, and work with any charge controller that can be configured for a gel charge curve.
After buying my system, I was criticized for not "shopping local". Funny thing, I went to the "local" stores first; they all had weird excuses for not being able to sell me what I wanted, said they would call back with a price, etc. Gexpro said "We have everything you need to finish the job. Where can we email your quote?"
(That said, BiG does have the best battery cables, made to order while you wait.)
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I am on my third set of batteries. The first 2 sets were golf cart batteries from Costco. The first set lasted 3 years which was OK but not the 5 or so years normally quoted. the second set lasted less than 2 years. I can't really explain that except that the batteries, bought in September, had dates of July and August on them instead of all September dates. Possibly some of them sat uncharged for a couple of months. I also had installed a new charging system and was experimenting with higher voltages. The water got down to the tops of the plates once. That's not good. In the end the inverter started tripping on low voltage every now and them. That's not good for them either so their demise was being hastened by each event. I had had company a couple of times towards the end there and overworking a small battery bank will have a disproportional effect since it is so bad to let them get down too far.
This last set is a set of Deka L16s from The Off-Grid Store in Kurtistown. They have been champs so far. The electrolyte SG has been higher in these L16s than it ever was for the previous set of golf cart batteries, another hint that there may have been something wrong with them from the beginning.
Anyhow all this talk of alternative battery technologies is fun but the FLA batteries are what is available. I still don't know simple things about the Tesla batteries like can I use my old charge controller, etc. There is nobody on the DIY websites that actually has them. That tells you something.
ETA: Not doubting my ability to kill batteries but the first set should have had a harder life than the second set. I didn't even have my solar set up ready when I bought them so they sat in my container being intermittently charged with a generator for a couple of months. I have a vague memory of having bought two a couple of months earlier then another 6 although even as a noob I should have known better than to do that. Then for over a year I only had 3 panels so they were being charged at a marginal rate. By all accounts they should have died early and the second set should have lasted lots longer.
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For FLA, especially the Interstate GC2's, it seems you are supposed to nuke them above 15v for a full charge. Especially off-grid where you can't rely on consistent sun hours. My first set started getting weak and sulphated until I ramped up the voltage. Of course then you have to check the electrolyte all the time...
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nuke them above 15v ... weak and sulphated ... check the electrolyte all the time ...
So ... the cheap batteries are a great deal, as long as your time is free?
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Perhaps not a good idea but that is a deal many first timers would go for.
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I am not sure what people are doing to them......they are fine if you do your part.
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Probably the best battery one could get is from the solar city guys or someplace else, the tesla powerwall lithium ion.
One 14 kWh Powerwall battery
$5,500
Supporting hardware
$700
Price for Powerwall equipment
$6,200
The good thing about Li ion tech is you can abuse the crap out of them and they will still last a long time. Getting chinese batteries you are taking a risk as the battery is only as good as the power management system. If it doesn't charge correctly or the circuits are cheap the battery loads will never balance out the cells making the battery pretty much useless over time.
I think you're better off going with the outback battery if you can't afford lithium tech, paying a bit more. If you are still on the grid, you could just pay the minimum, and when the batteries get down to 20-25% the grid or a generator could switch on to keep the batteries topped up. You might think that is excessive to recharge the batteries after only using 20%, but, doing this can make a battery last 5-10+++X long as dropping down to say 50%. The lower you take a battery ... The more you abuse any type of battery, you shorten it's life considerably.
There are other factors such as charge rate, maintenance, age, etc...etc but most new people will kill the life of batteries by running them down too far.
Batteries are expensive and you want them to Last for as long as possible.
http://www.mpoweruk.com/life.htm
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other factors such as charge rate, maintenance, age, etc...
Availability is a pretty important factor.
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Ericip- do you have a link for your Powerwall in an off grid system? Would be very interesting in reading it.
As for GC, Interstate here in Hilo used to have a good price, but more than 10 years since I checked.
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Thanks for that link about batteries ericlp. Wow. LOTS of information there!
