Wants best batteries for solar?? The go for lithium ion batteries with about 17 years life span and use up to 6000 cycles at 100% dod.Gel batteries are a waste of time and money as they last only about 5 years or less and takes more space to build a bigger bank. 2 x 4.8 kw takes the space of about 8-9 of 200ah Gel batteries.