The Solar Charge Controller is an important piece of the Solar Power System, its primary function is to receive power the Solar Panel managing the voltage going into battery storage.
They ensure that the deep cycle batteries connected to the Solar Power System don’t overcharge while the Solar Array collects energy. During the night when there is no longer any power, it prevents current reversing back to the panels.
There are 2 variations:
PWM (Pulse Width Modulation)
This type Charge Controller holds the voltage at a safe maximum until the battery reaches full capacity, after which it will “trickle charge” to simply top it up.
It’s been around for many years and is inexpensive, there are drawbacks to this component, however. Read more about that here.