Surrette Battery Company, makers of Rolls deep cycle lead-acid batteries, offers their S4000 and S5000 lines which are specifically tailored for use in off-grid renewable energy systems. Available in 2, 4, 6, 8 and 12 volts, and from 80 to 2430 amp hour capacity at the 20 hour rate. For reliability, durability, easy maintenance and ongoing product support, think Surrette