If you want to add solar.

[scrubjaysnest]

Here are some links to review before adding solar. Also do an energy audit.

Introduction to 12 volts, his State of Charge, SOC, chart is wrong for most batteries. The 12volt Side of Life (Part 1)

The next two are battery info sites.

Car and Deep Cycle Battery FAQ, Battery Manufacturers and Brand Names List, and
SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank

And finally the 20 Golden rules of Solar.

RV Electrical