Deep Cycle batteries are used for solar panel installations.
Deep cycling batteries are specifically designed for solar systems, NOT car batteries. Deep Cycle batteries are designed to deliver a small amount of current over a long period of time. Always go for the best batteries you can afford and as many amp hours as you can store.
A car battery is designed to give a massive surge of current in a few seconds. So a car battery has thin plates for minimal internal resistance, while a Deep Cycle battery has thick plates for longevity.