Have you priced LTO? They're rather staggeringly expensive for their capacity. The cycle life is excellent, but they excel in very high C-rate applications (10C-20C), which is the opposite of what you need for off-grid systems. If an off grid system is getting anywhere near C/10 discharge rates, you're going to be in the dark awfully soon.
It's old tech, it's boring, but it works fine... flooded lead acid. Don't fully discharge it in the winter, and they won't freeze. They'll cycle just fine in the cold. Well tested, proven, and unless you're full time living and heating an interior space that can be lithium-friendly, they're the right option. Disconnect all the loads and run them on float in the winter with a high, vertical, south facing panel (obviously swap that if you're in the southern hemisphere), and they'll do just fine.
Yeah, lead wins hands down. This is a few years out of date now, but when speccing out my system I did a bit of analysis of battery types. We went with OPzS, and so far, so good.
Recycled Lithium Ion is much cheaper still, but more risky (and less maintenance). You'll have to do some pretty fanatic inbound QA to determine whether all your cells are safe to use. but if you do that and fuse your cells individually you should be able to make that work.
It's old tech, it's boring, but it works fine... flooded lead acid. Don't fully discharge it in the winter, and they won't freeze. They'll cycle just fine in the cold. Well tested, proven, and unless you're full time living and heating an interior space that can be lithium-friendly, they're the right option. Disconnect all the loads and run them on float in the winter with a high, vertical, south facing panel (obviously swap that if you're in the southern hemisphere), and they'll do just fine.