Aren’t lead acid batteries great for this purpose? They have advantage over lithium in stationary setups because weight is not an issue and they can be “daisy chained” many many times. I’m unaware of more cutting edge alternatives and the way the electrical companies handle solar is confusing IME
Lead acid batteries don't much like being cycled heavily. Even the ones explicitly designed for it (the average car battery is not) have about a tenth of the lifespan of lithium ion.
LiFePO4 is probably the chemistry best suited to it ATM. Lasts a long time, more stable, pretty cheap, and just a bit less energy density than other lithium ion options. Sodium-ion is looking promising but only just entering the market AFAIK.
Does this mean LA would be a feasible option for longer-cycle storage, IOW keeping a reserve topped up most of the year for those duldrums weeks with little solar or wind?
For long term storage, the right batteries don't exist yet (commercially). The good options are going to be one of sodium ion, flow batteries, or thermal batteries.
In addition to the fact that it doesn't really work better for that either, it's just not as safe as lithium iron phosphate.
I think it still loses out to lithium-ion on cost/kWh, and batteries in general are still a bit expensive for storage on the timescale of months.
I dumped my 24V dual LA battery setup for a single 24V LFP battery for my inverter/UPS backup. LFP supposedly has a 10-15y life based on the 4-5000 charge cycles most cells claim. Sodium ion is on the way as well. My setup gives me about 10-12h of backup for critical loads (my PC, lights, fans).
I have a 5 kWp solar plant that produces ~25kWh per day, but it is grid-tied. I considered a hybrid setup with LFP battery back up, but decided to separate the two systems to avoid a single point of failure.
They're not great.
LiFePo4 however is excellent and reasonably low cost these days
"PO" not "Po" (I was wondering what Polonium was doing in here lol)
Whatever it is doing, it won't be doing it for very long ;-)