What’s the Difference between MPPT and PWM Controller In Solar Energy System?

What’s the Difference between MPPT and PWM Controller In Solar Energy System?

If you plan to install an off-grid solar system with a battery pack, you will need a solar charge controller. It is a device placed between the solar panel and the storage battery to control the electricity generated by the solar panel into the battery. The main function is to ensure that the battery is properly charged and prevent overcharging. Whether you want to live a off grid life, or you just go to travel with RV, you must need to take care of the connection between solar panel and storage battery.

Basic Principle of Charge Controller

  1. PWM

Pulse width modulation (PWM) is the digital output of the microprocessor to control the analog circuit, is a method of digital encoding of the analog signal level. Digital control of analog circuits can greatly reduce the cost and power consumption of the system. Many microcontrollers include PWM controllers.

The basic principle of PWM control is that narrow pulses of the same impulse but different shapes have the same effect when applied to the inertial link. PWM control principle, the waveform is divided into 6 equal parts, which can be replaced by 6 square waves.

  1. MPPT

MPPT control is generally completed through the DC conversion circuit, the photovoltaic cell array and the load are connected through the DC circuit, the maximum power tracking device constantly detects the current and voltage changes of the photovoltaic array, and adjusts the PWM drive signal duty ratio of the DC converter according to the changes. Overall, the MPPT controller tracks the maximum power points in the solar panel in real time to maximize the efficiency of the solar panel. The higher the voltage, the more power can be output through the maximum power tracking, thus improving the charging efficiency.


What do MPPT & PWM for?

  • Output power adjustment function.
  • Communication function: identity function and protocol communication function, such as RS485 Ethernet, wireless network and other background management functions
  • Protection function: electrical protection, reverse connection protection, short circuit protection, over charge protection, over discharge protection, etc.


Difference between MPPT & PWM 

1) MPPT controller is more expensive than PWM controller, but MPPT controller has higher charging efficiency, especially in cold weather conditions. The MPPT controller also allows more photovoltaic (PV) panels to be wired in series (high voltage differential), which is another big advantage. In this case, the cross-sectional area of the connecting cable can be greatly reduced, resulting in a corresponding reduction in the overall system cost.


2) Compared with MPPT controller, the biggest disadvantage of PWM controller is its efficiency. PWM charging controller cannot charge the maximum power generated by PV array, and its overall efficiency is usually between 65-85%. On the other hand, MPPT controller can ensure that the solar array is always in the best running state. In some cases, such as when the weather is cold, MPPT provides a 30% higher charging efficiency than PWM (high charging efficiency).

3) PWM mode technology is mature, the circuit is simple and reliable, the price is cheap, but the component utilization rate is low, suitable for small systems, the temperature range of the solar charging unit is 45-75℃. MPPT controllers are a better choice for large systems, and their higher efficiency means good economic benefits. In addition, the MPPT controller enables the user to obtain the maximum power from the PV array, which is an obvious advantage when there is additional power demand and limited space to expand the size of the PV array.


It is a must when you are frequently using solar energy system, which can be a guard of you safety. So which one do you prefer? In the solar battery energy storage system industry, Huarigorenegy has extensive experience in solar storage batteries, solar inverters and solar panels and continues to innovate itself to help customers achieve their goals. It provides integrated solutions for customers to create and transform scenarios. If you have the need to customize solar panels and solar charge controller, please don’t hesitate to get a free quote.

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