Solar charge controllers control the energy coming from the solar panels, adjust the current and voltage, then send it to the batteries. The charge controller protects the system by preventing the batteries from being overcharged and overdischarged. A charge controller is needed in every solar energy system. Charge controllers are divided into two as PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracking).
PWM is an acronym for Pulse Width Modulation. PWM charge controllers can be thought of as an electrical switch between the solar panel and the batteries. The switch is quickly turned on and off to obtain the appropriate voltage to charge the batteries. As the batteries are charged, the charging current is slowly reduced.
MPPT is an acronym for Maximum Power Point Tracking. MPPT is a technique used to monitor and regulate energy from solar panel to batteries. Solar panels give variable output due to weather conditions. MPPT charge controllers can match panel voltage to battery voltage to maximize charging efficiency. In these systems, the full power of the solar panels can be used by establishing a balance between voltage and current according to the equation P = V x A. For example; When the weather is cloudy, the amount of current drawn from the panels is reduced to maintain the voltage. When the sun reappears, more current is allowed again.
The main difference between PWM and MPPT charge controllers is that MPPT devices are more efficient. MPPT charge controllers can provide up to 30 percent increase in charging efficiency over PWM. In PWM systems, panel voltage and battery voltage should be matched. MPPT systems allow the panel array to be at higher voltage than the batteries. This means more flexibility for system growth.
On the other hand, MPPT controllers are more expensive than PWM controllers. Therefore, PWM charge controllers are still used in small systems where efficiency is not critical.
The size of the solar energy system should be considered when choosing a charge controller. MPPT charge controllers are best for professional applications. PWM charge controllers, on the other hand, can provide sufficient performance in small applications that do not need many features. Particularly in small projects, the efficiency gap between MPPT and PWM may not be enough to justify the overprice. In large projects, it plays a big role in how well the system will perform.
