MPPT & PWM: Which Solar Charge Controller is Better?

What’s the solar charge controller?
A solar charge controller (also known as a solar panel voltage regulator) is a controller that regulates the charging and discharging process in a solar power system.
The main function of the charge controller is to control the charging current flowing from the PV panel to the battery, keeping the flowing current from being too high to prevent the battery bank from being overcharged.

Two types of the solar charge controller
Both MPPT and PWM are power control methods used by charge controllers to regulate the flow of current from the solar module to the battery.
While PWM chargers are generally required to be cheap and have a 75% conversion rate, MPPT chargers are a bit more expensive to purchase, the latest MPPT can dramatically even increase the conversion rate by up to 99%.
The PWM controller is essentially a switch that connects the solar array to the battery. The result is that the voltage of the array will be pulled down close to the voltage of the battery.
The MPPT controller is more complex (and more expensive): it will adjust its input voltage to take the maximum power from the solar array, and then translate that power into different voltage requirements for the battery and the load. Thus, it essentially decouples the voltages of the array and the batteries, so that, for example, there is a 12V battery on one side of the MPPT charge controller and panels connected in series to produce 36V on the other side.
The difference between MPPT & PWM solar charge controllers in application
PWM controllers are mainly used for small systems with simple functions and low powers.
MPPT controllers are used for small, medium, and large PV systems, and MPPT controllers are used for medium and large systems with multi-functional requirements, such as power stations.
Special MPPT controllers are used in small off-grid systems, caravans, boats, street lights, electronic eyes, hybrid systems, etc.

Both PWM and MPPT controllers can be used for 12V 24V 48V systems, but when the system wattage is higher, the MPPT controller is a better choice.
MPPT controllers also support large high-voltage systems with solar panels in series, thus maximizing the use of solar panels.
The Charge Difference of MPPT & PWM Solar Charger Controller
Pulse width modulation technology charges the battery in a fixed 3-stage charge (bulk, float, and absorption).
MPPT technology is peak tracking and can be considered multi-stage charging.
The power conversion efficiency of the MPPT generator is 30% higher compared to PWM.
PMW includes 3 levels of charging:
Batch charging; Absorption charging; Float charging

Where float charging is the last of the 3 stages of charging, also known as trickle charging, and is the application of a small amount of charge to the battery at a low rate and in a steady manner.
Most rechargeable batteries lose power after they are fully charged. This is caused by self-discharge. If the charge is maintained at the same low current as the self-discharge rating, the charge can be maintained.
MPPT also has a 3-stage charging process, and unlike PWM, MPPT has the ability to automatically switch charging based on PV conditions.
Unlike PWM, the bulk charging phase has a fixed charging voltage.
When the sunlight is strong, the output power of the PV cell increases greatly and the charging current (Voc) may quickly reach the threshold. After that, it will stop the MPPT charging and switch to the constant current charging method.
When the sunlight becomes weak and it is difficult to maintain constant current charging, it will switch to MPPT charging. and switch freely until the voltage on the battery side rises to the saturation voltage Ur and the battery switches to constant voltage charging.
By combining MPPT charging with constant-current charging and automatic switching, solar energy can be fully utilized.

In summary, I think the MPPT advantage is better, but PWM chargers are also in demand by some people.
Based on what you can see: here is my conclusion:
MPPT charge controllers are best suited for professional owners looking for a controller that can perform demanding tasks (home power, RV power, boats, and grid-tied power plants).
PWM charge controllers are best suited for smaller off-grid power applications that do not require any other features and have a larger budget.
If you just need a simple and economical charge controller for small lighting systems, then PWM controllers are for you.

Post time: May-04-2023