The number of times is called hertz. Battery - A device for storing and generating electricity. The purpose is to prevent over charging of the batteries and disconnect the bank at night.
Some controllers also disconnect the load from the battery when the battery is empty.
Conductor - A substance or medium which conducts electrical charge. DC - Direct Current. A flow of electricity in one direction and of substantially constant value. Deep Cycle - The class of battery that can be drawn down relatively deeply without harm. Electron - A subatomic particle of energy charge.