The main type of energy storage device used in most modern off grid solar power systems is the deep cycle battery. A deep cycle battery is designed to be deeply discharged over a long period of time unlike a car starter battery which is more suited to delivering short bursts of power such as that needed to crank over a cars starter motor.
Off-grid power systems are usually installed in locations that have no access to a larger public power network. These types of systems are also refereed to as "remote area power systems" (RAPS) or "stand-alone power systems" (SAPS) and most often consist of solar panels or wind turbines or a combination of both.
A Solar regulator aka charge controller is used with a stand alone or off grid solar power system or in a hybrid grid connect system with batteries, in a grid connect solar power system with no batteries there is no need for a charge controller.
Going off grid and freeing yourself from the eternal cycle of monthly electricity bills is a very appealing idea, and at least on the surface its seems like a viable power generating option.