My wife and I are building our retirement home in Maine and opted for "off grid" considering the federal tax rebate, the cost of connecting to commercial power and the bills going ahead.
When I looked at the different battery chemistries, I decided that either flow batteries or NiFe would be the direction that made the most sense to me.
The designer/salesman I dealt with did a wonderful job designing a system which he felt would serve our needs. He suggested a 7.6Kw solar array and a 400ah lithium ion 48V battery. I was told to expect a 7-to-9-year service life for the battery at a cost of $17,000. Best case, a couple of thousand dollars a year for power storage. I found that unacceptable.
I modified the system to a 10.4 Kw array with a 500ah 48V NiFe battery system. I liked the concept of the flow batteries, but at the time (three years ago) I could not find a vendor who would sell the product I was looking for into the US.
When I went looking for NiFe batteries, I found CIYI battery in China. From my "research" there are no longer any manufacturers of NiFe batteries in North America. There are a couple of companies selling NiFe batteries in the US, but they are buying them from China with a substantial mark-up.
These batteries are large and heavy (3,800# filled) and require watering with demineralized water (shopping for a batery watering system now), but even with the tariff imposed by the former resident of the White House (cost me an extra $2,000) I was able to acquire my batteries for around $13,000 including shipping, tariff and import agent fees. For the same batteries a distributor in Colorado wanted $22,000.
So far, I am really pleased with my decision. The batteries arrived already filled with electrolyte.
The fact that these batteries will outlast me is a major plus to me.