I'm in Albuquerque, NM, US. I'm most interested in the low-cost DIY-ish approach to this project, and your thread is inspirational along that front. After reading it, I did stumble on a discussion about the use of used UPS batteries,
you may save cash up front, but have endless headaches and short life span as well as ongong range anxiety dealing with use UPS or old golf cart batteries from the golf course or salvage yard..... save up and go with LiFePO4; something like CALBs.
Dan - in santa fe