A solar charge controller, also known as a solar regulator, is a battery charge regulator connected between the solar array and the battery. The charge controller in a solar installation sits between the energy source (solar panel) and storage (battery). Its job is to regulate the solar output to ensure the battery is charged properly and not overcharged, which helps preserve the life and health of the battery. DC-coupled solar charge controllers have been around for decades and are used in most small off-grid solar power systems.
Solar charge controllers work by regulating the voltage and current from the solar panel to the battery. The solar charge controller detects and monitors the battery voltage, reducing the current when the battery is fully charged. The controller remains on a float charge to keep the battery in a ready state.
Charging controls come in all shapes, sizes, features, and price ranges. Cheaper but less efficient Pulse Width Modulation (PWM) charge controllers and efficient and inexpensive Maximum Power Point Tracking (MPPT) charge controllers.