The early pwm solar controllers are generally like this. The electrical structure is relatively simple. It is composed of a power main switch, a capacitor, a driver and a protection circuit. It is actually equivalent to a switch, connecting the components and the battery. At the same time, the voltage of the components will be pulled down close to the voltage of the battery pack. This controller adopts the three-stage charging method of strong charge, balanced charge and floating charge.

The controller of this charging method can solve the problem that the battery is not fully charged and ensure the service life of the battery. But it should be noted that the charging efficiency of the PWM solar controller will be affected by the temperature. When the temperature of the solar cell is around 45~75℃, the charging efficiency is the best.
The PWM solar controller can only be matched with the relevant voltage. For example, the 12V system panel can only be matched with the 12V controller and battery, which is suitable for some small off-grid systems below 2kw. The structure is simple, the user wiring is convenient, and the price is relatively cheap.