I haven't seen any degradation, but I also haven't really looked or tested. The battery sees only occasional use (mostly weekends these days) and I have the operating voltage window set to a pretty conservative range for longevity of the cells -- something like 3.7 - 4.05v, I think. The battery powers my off-grid barn / workshop, through a Growatt off-grid inverter -- I can't remember if it's a 6kw or an 8kw. The building is 30x50, all steel on a concrete slab, and I believe I have 16 solar panels roof-mounted, 315w apiece, if memory serves. A Batrium BMS keeps an eye on things, but my use makes it little more than a cell monitor and glorified balancer. It does have a shunt and breaker that it can remotely trip, but I don't recall that it has ever had to do that. I'm attaching one photo, but it's not the best -- just the back side of all the cells in the rolling server rack where I mounted them. You can also see the inverter a bit, mounted below the service panel behind the battery.
I have an small office and 3/4 bathroom there, heated and cooled with a 1-ton mini-split. Sometimes I leave it on all the time, sometimes I turn it off. I have a shallow well pump to supply water to the building. Tons of overhead fluorescent tubes. I run all manner of 110v tools at will, and occasionally some 220v tools. (The inverter isn't quite strong enough to start my 80-gallon air compressor, which is kind of disappointing. I haven't looked into a start kit or anything like that for it, because I don't need it badly enough to bother -- I've got an identical unit up at the on-grid garage I can use when needed.) The inverter will run my manual engine lathe and CNC mill, both through a three-phase VFD. There's a standard 40-gallon electric water heater for the office/bath, but I have rewired it down to one element so it doesn't overload the inverter -- and I also have a switch to turn it on and off as needed, since it's pretty rare that I require hot water down there.
For nearly a year, I had someone living down there and using the office as an efficiency/studio sized apartment, so all systems stayed on 24x7. Everything performed flawlessly with the exception of during a blizzard week when Texas got over a foot of snow and temps didn't get above zero for five or six days straight. With the solar panels covered, I ran an 8kw gas generator into the Growatt inverter/charger for a couple of hours during the day to make sure the batteries had enough charge to make it through the nights without generator racket. As soon as things warmed up and the panels melted off, the system went right back to normal operation.
I am keeping the Leaf-based system as-is down at the shop, but I recently bought a couple tons of BYD batteries (LiFePO4 chemistry) that I plan to deploy up at the house -- that's another project for another day and another thread! I am hoping for it to be a hybrid grid-tie / full home backup solution when all is said and done. Hope this info is helpful or at least interesting as you build out your own Leaf-based battery.
Cheers, John
I ordered more of the braided wire mesh. 
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