We know there are two types of charge controller of Maximum Power Point Tracking charge controllers (MPPT) and Pulse Width Modulation (PWM). But which type do i need?
MPPT charge controllers
are the most efficient type on the market but are also more expensive. MPPT and PWM technologies are not mutually exclusive, you do not have to use one or the other.
MPPT charge controllers have the best performance, but they are more expensive
Why do MPPT charge controllers have the best performance? Because they allow your solar panels to operate at their optimum voltage levels in varying light conditions; summer, winter, morning, noon, cloudy etc… The MPPT charge controller takes the voltage output of the solar panels, and compares it to the battery voltage. It then figures out what is the best voltage to get maximum AMPS into the battery. Remember it’s the AMPS that matter. Said another way, the MPPT controller tracks the best voltage level and then down converts it to the voltage of your system (12, 24, 48VDC). This “tracking” of the optimal power point improves performance by as much as 30%. PWM charge controllers
on the other hand, reduce the voltage from the solar panel to that of the battery bank resulting in a decrease in efficiency. The efficiency loss depends on the size of the voltage mismatch between your panels and batteries.
Another benefit of MPPT charge controllers is that many can accept high input voltages (up to 120+V DC) and efficiently down convert the DC voltage to that of your system (e.g. 12, 24, 48VDC, etc) which means you aren’t losing any generated power and you are able to use what you generate more efficiently. Additionally, using a much higher DC voltage on the input side allows you to use thinner wire, decreasing your wire cost and making installation easier.
PWM charge controllers are less expensive and you will find a wider selection of models available. They are ideal for smaller systems where price point is critical or where the additional power is not really needed. Remember, your solar charge controller is an integral part of your system, stick with the brand names from reputable dealers for safe, long term success with your solar electric project!