primarily for small scale DIY
Cost effective?
Used electric car batteries.
I think you’ll need to be more specific.
Batteries that are ready to wire together and integrate into a small solar system?
A battery station with inverter and charge controller built in, designed to replace a backup generator?
Individual 18650s that are best for building a battery bank to store up solar power?
Well whatever the most cost effective method of storing DC power from solar panels would be. I figure deep cycle lead-acid is probably still the cost per watt leader, but was just pondering the question who anyone who knows a bit about the topic.
Hmm, so it’s a question of what gets the most watt-hours stored for the least money?
Is there a size limit to the total battery pack?
Is the solar controller part of the budget or already paid for?
I hope I’m not being overly pedantic, we may have already narrowed it down to where someone can jump in with a recommendation.
From what I’ve seen, the controller is the expensive part. If you have that, then it’s a search for the cheapest battery type that is compatible with the controller. If it is made to take care of lead acid, then those are probably your best route for less expensive storage.
Downsides are that they do need maintenance and some knowledge of how they work to keep lead acid going for the long haul with top performance, and they take up more space than lithium based batteries.
They also have a shorter lifetime and perhaps more importantly, worse max depth of discharge. Compared to more modern battery chemistries, I suspect you end up paying more with lead acid to get the same amount of available power (just not up front) over a similar battery lifespan.
You’re right! A lead acid battery should not be discharged past half of its capacity, it shortened the lifespan of the battery if you do.
So, you need at least double your regular watt-hours that you use overnight in storage plus the batteries will need ongoing maintenance for it to last as long as possible.
I’d probably go with a renology battery via amazon or an eg4 battery from signature solar or from solar sovereign for lithium Ion batteries for long term use.
I second u/seth’s recommendation on Will Prowse as a good source of knowledge on this topic. I agree with avoiding lead acid as it’s less cost effective for a long term solution. I think they also have some more maintenance involved with them compared to li ion.
Don’t the lead-acid have better longetivity tho, since you can change the acid?
Yeah, I guess you could recondition one kinda like how this guy does it. I had never heard of doing that before. Thanks for the info.
I would still opt for li ion even with that though. Lithium Ion has a 2x greater depth of discharge(usable stored power) and 2-3x the lifetime (not taking into account any reconditioning) when compared to lead acid. That equals 4-6x the utility theoretically at around double the cost. That would make li ion 2-3x more bang for your buck compared to lead acid.
But there may be some case, for using a cheaper lead acid on a small scale project. Just be aware of the maintenance requirements of them and the increased cost if you do end up using it on a long term project.
The acid is not the problem. It’s the sulfation of the plates (or mats) in flooded cell (and absorbent glass mat) batteries that ruins the batteries.
If you want off-the-shelf, check out Will Prowse’s channel on yt, he explains in great detail the good and bad points of a lot of commercial batteries, inverters, panels, and updates his recommendations as new ones come out. It really depends on what your power needs are, but in general, today’s 48V server rack LiFePO4 batteries are pretty safe and easy to set up, don’t take up much room, can discharge even down to 0% for thousands of cycles, and can charge quickly.
The site I mostly end up back at for detailed technical information, bugs, updates, and DIY support is his forum, diysolarforum.com . There are a number of technical support employees from different solar vendors who have accounts there and occasionally respond to questions about their companies’ products, and there are forum rules to prevent them from marketing there. I’ve seen a few companies raked over the coals in those forums for poor phone or email support/response times, and some have even improved their support in response.
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The most cost effective ones are not exactly on the market.
You order the parts and the needed tools/devices from the land of the free mail order businesses, and then you follow some youtube tutorial for instructions how to build your battery. Saves you thousands.
It is a good way to have a fire hazard at home, if you don’t know what you’re doing.
lithium ferrophosphate type battery for deep cycling
What is this even
