mppt vs pwm

MPPT vs PWM : Which Charge Controller is Better?

In this post, I’m going to compare MPPT and PWM charge controllers.

So if you’re looking for a DEEP comparison of these two types of charge controllers/regulators, you’ve come to the right place.

Because in today’s post I’m going to compare MPPT vs. PWM in terms of

  • Working Principle
  • Operation
  • Performance
  • Pricing and value
  • Unique features
  • Expert Recommendation
  • And lots more

What a Solar Charge Controller do?

A solar charge controller (also known as a solar panel voltage regulator) is a type of controller that regulates the charging and discharging process in the solar power system.

The main function of the charge controller is to control the charge current flowing from the PV panels to the battery, keeping the current flowing not too large to prevent the battery pack from overcharging.

There are 2 types of charge controllers on the market:

  1. MPPT Solar Charge Controller
  2. PWM Solar Charge Controller
mppt vs pwm comparison
mppt vs pwm comparison

MPPT vs PWM: Principle

MPPT and PWM are both power control methods used by the charge controller to regulate the current flowing from the solar module to the battery.

PWM charger is usually asked for a cheap price and has a 75% percent conversion rate, buying an MPPT charger is a little expensive.

However, the latest MPPT can massively improve the conversion rate, up to 99%.

What is MPPT

MPPT stands for Maximum Power Point Tracking. It is a technique for tracking and regulating the output energy from the solar panel to the battery.

MPPT detects the solar panel output voltage and current in real time and continuously tracks the maximum power (P=U*I).

It regulates the power output voltage accordingly so that the system can always charge the battery with the maximum power.

MPPT Charge Advantage
MPPT Charge Advantage

What is PWM

PWM is short for Pulse Width Modulation, it’s a technique to modulate the width of the pulse according to certain rules, thus changing the voltage and frequency of the energy outputted by the solar panel to charge the battery.

The PWM controller can be considered as an electrical switch between the solar panel and the battery packs.

pwm charge controller in small solar power system
pwm charge controller in small solar power system

MPPT vs PWM: Charge Difference

Pulse Width Modulation charges the battery with fixed 3-stage charging (bulk, float and absorb).

The MPPT technology is Peak Power Point Tracking and can be thought of as multi-stage charging.

Compared to PWM, MPPT Generator is 30% more efficient at converting power.

PMW 3 Stage Charging:

Bulk Charge: The bulk generation stage indicates that the PV system is delivering the most power to the solar battery, at this time, the battery voltage is low, the system is supplying the battery with high current and voltage.

There is a maintenance point (overcharge protection setpoint) and if battery voltage is higher than this value, bulk charging should stop.

Absorbing Charge: After the first stage of charging, the battery waits for a period of time to allow the voltage to drop, and then it enters the balanced charging stage. This stage is also known as fixed voltage charging.

Float Charge: Float charge is the final stage of a 3-stage charge, also known as trickle charge, which is a small amount of charge applied to a battery at a low rate and in a steady manner.

Most rechargeable batteries lose power after being fully charged. This is due to self-discharge. The charge can be maintained if the charge is maintained at the same low current as the self-discharge rate.

MPPT Multi-Stage Charging:

MPPT also has a 3 stage charging process, unlike PWM, MPPT has the ability to automatically switch the charging based on the PV condition. here is how:

Bulk Charge: In the bulk charge stage, the mppt controller operates in Vmpp mode and actively adjusts the output voltage, allowing the system to harvest the most power from the PV array.

Unlike PWM, the bulk charge stage has a fixed charge voltage.

When the sunlight is strong, the output power of the photovoltaic cells increases greatly, and the charging current (Voc) may soon 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 difficult to maintain constant current charging, it will switch to MPPT charging.

and freely switch until the voltage on the battery side rises to the saturation voltage Ur, and the battery switches to constant-voltage charging.

By combining MPPT charge with constant current charge and automatic switching, it is possible to fully utilize solar energy to charge the battery quickly.

Balanced charge / boost charge: As the battery voltage reaches the boost voltage set point, the solar controller gradually adjusts the charging current to keep the battery in the charging process without overvoltage.

Absorb Charge: In the Absorb Charge stage, as the battery voltage increases, the charge current gradually decreases, when the charge current drops to about 0.01C, the constant voltage charge ends.

Float charge: The charging voltage (Uf) in floating charging is slightly lower than in constant charging.

The main purpose of this charge is to compensate the battery voltage drop to fully charge the battery.

MPPT Charging Advantages:

  1. MPPT Charger Fast scan of the whole I-V curve and tracking of the panel power point in seconds.
  2. It has the ability to maximize solar system energy utilization rate and makes conversion efficiency up to 97%.
  3. Increase charge efficiency by at least 20% percent over PWM charge controller
  4. Enable the solar energy systems to gain larger amount of power.
  5. With the same load, the use of MPPT charging method can lower the power of PV modules and reduce module cost.

the MPPT Charge Curve is shown below:

mppt charge curve
mppt charge curve

MPPT vs PWM Solar Charge Controller: Application

The PWM controller is mainly used in small systems with simple functions and low power applications.

MPPT controllers are available for small, medium and large PV systems, and MPPT controllers are used for medium to large systems with multi-function requirements, such as power farms.

In small off-grid systems, caravans, boats, street lights, electronic eyes and hybrid systems, etc., dedicated MPPT controllers are used.

Both pmw and mppt controllers are available for 12V 24V 48V systems, but when the system watts is higher, mppt controllers are the better choice.

The MPPT controller also supports large high-voltage systems with solar panels connected in series, thus maximizing the use of solar panels.

MPPT vs. PWM: Pros and Cons

MPPT and PWM charge controllers perform the same tasks in a solar power system, and the advantages and disadvantages of both technologies are discussed below.

MPPT Charge Controller Pros

  • Maximum power voltage tracking algorithm increase power conversion rate up to 99%.
  • 4-stage charging
  • Stackable for large off-grid power systems
  • Max current handled up to 150 Amps
  • Max input voltage up to 400 volts
  • Provides flexibility as the system grows
  • Equipped with multiple protection
  • Multiple modes for load configuration
  • Remote monitoring or Bluetooth connection
  • Capable of charging lithium battery (Lifepo4)
  • Integrated with wind power system

MPPT Regulator Cons

  • Higher price (typically twice the cost of a PWM regulator)
  • Heavier and larger than a PWM controller

PWM Solar Controller Pros:

  • PWM Regulator has mature and proven techniques
  • PWM Regulator has a simple structure and low cost.
  • Easy to use in smaller systems
  • Smaller budget for a small tiny house project
  • Support charge lithium batteries

PWM Solar Charge Controller Cons:

  • Low conversion rate
  • Input voltage must match battery bank voltage
  • Low scalability for system growth
  • Inability to handle higher voltages
  • Less load mode
  • Less protection

MPPT vs PWM Charge Controllers: MPPT Advantages

In order to charge the battery, the output of the solar array voltage must higher than the input voltage of the battery.

The charging current will be close to 0 (zero) if the solar panel output voltage is lower than the input voltage.

The output of the solar panel is not a fixed value, the curve changes a lot during the day, many factors such as sunshine intensity, ambient temperature, even humidity can affect the solar conversion.

When using a PWM regulator, due to the PWM system lacks flexibility, the output voltage and current remain constant even if the solar input changes.

This results in a great waste of energy.

A PWM controller acts like a switch and connects the solar array directly to the battery during charging. This requires the solar array to operate in a voltage range typically below Vmp.

In a 12V solar system, the battery voltage range is typically 11-15V, but the array Vmp voltage is typically around 16 or 17V.

Since PWM controllers don’t always work at PV array Vmp, this will cause energy loss.

The greater the difference between the battery voltage and the array Vmp, the more energy is wasted.

Thanks to the invention of the MPPT controller, through the MPPT algorithm, the controller automatically monitors the high power points of the PV to ensure maximum energy extracted.

In a solar power system, the cost of solar panels and batteries make up 80-90% of the total budget.

And the controller only takes up the other 5%-10%.

However, a solar controller with a 5% budget can optimize the system to its best performance if you choose the right solar chargers.

Here is an example for you to better understand the MPPT advantages: If you have a 1000W panel system, if you upgrade the PWM controller to an MPPT type, you only need to use 700W solar panels to get the same power.

The price of solar panels in the market is about $2/W. Then the total cost of solar panels can be reduced to $650.

In such cases, in larger systems, the savings can be greater, including the cost of upgrading the panels, wiring cables, solar inverter and more.

In addition, the amorphous silicon solar panels work better with an MPPT controller.

MPPT vs. PWM: Circuit Board Differences


Conclusion: Which Charge Controller Is Best For You?

There you have it – an MPPT vs. PWM showdown on a feature-by-feature basis.

MPPT wins for me, but the PWM charger still has room to run.

Based on what you’ve seen: Here’s my conclusion:

MPPT Charge Controller is best for professional owners who are looking for a controller that can perform demanding tasks (home power supply, RV power supply, boat, hybrid wind solar power and on grid power station).

PWM Charge Controller is best for small off-grid power applications that don’t need any other features and have a large budget.

If you just need a simple and economical charge controller for a small lighting system, the PWM controller is the way to go.

What do you think? Are you going with PWM or MPPT? Did I miss any major features? Let me know in the comments!

Related Questions:

[saswp_tiny_multiple_faq headline-0=”h4″ question-0=”Why is it better to use mppt than pwm?” answer-0=”In terms of energy efficiency, investment-output ratio, quality, additional features and many other factors, mppt controller is more worth buying than pmw controller. A large number of mppt controllers are coupled with Bluetooth remote control, which can read and adjust the controller remotely. There are many review videos on youtube, under standard test conditions (STC), MPPT charge controller bring more than 30% charging efficiency.” image-0=”” headline-1=”h4″ question-1=”Which is better: PWM or MPPT for solar panels?” answer-1=”From the working principle, no matter mppt or PWM, their work is to regulate the current from the energy source (Solar Array) to the battery to prevent the current from overcharging the battery. Whether you choose mppt or pmw, be sure to choose a big brand, high quality, widely reviewed charger.” image-1=”” headline-2=”h4″ question-2=”Is it better to use mppt or pwm?” answer-2=”Is more recommended to use mppt, MPPT can convert solar energy with high efficiency, better battery protection, convenient remote control, and more setting functions. MPPT’s temperature compensating function supports monitoring the solar panel temperature, battery temperature and ambient temperature to automatically adjust the charging process to store additional energy. It is more beneficial to the health of the battery.” image-2=”” headline-3=”h4″ question-3=”What is the difference between mppt and pwm?” answer-3=”Both MPPT and PWM work to regulate the charging from the panel to the battery, thus maintaining and protecting the battery. MPPT uses the Most Power Point Tracking operating mechanism to control this process. The PWM charger, also does the control work but is more similar to the role of a circuit breakers.” image-3=”” headline-4=”h4″ question-4=”MPPT vs PWM for small 12v system?” answer-4=”MPPT controllers and PWM controllers can both support 12V systems very well, but in general, MPPT controllers perform better and have a higher ROI.” image-4=”” headline-5=”h4″ question-5=”What are the factors in choosing a Charge controller? ” answer-5=”There are many factors that go into selecting a solar controller, including brand, quality, additional features, size, and so on. The most important thing is to pick the right amperage according to panel watt, and battery voltage of solar systems.” image-5=”” headline-6=”h4″ question-6=”Are MPPT controller worth it for 12v panel system? ” answer-6=”an mppt controller is a good choice for 12v panel system, MPPT brings a lot of advantage compare to PWM charge controller such as energy transfer efficiency.” image-6=”” headline-7=”h4″ question-7=”Is there such thing as auto PWM/MPPT switch in solar charge?” answer-7=”in rumors it does, but actually no such kind of PWM/MPPT switch in solar charge controller.” image-7=”” headline-8=”h4″ question-8=”Are PWM controllers any good?” answer-8=”The biggest advantage of PWM is the low price, there are many good quality PWM controller on the market, if the system requirements are not high, the overall budget is low, PWM controller is also a good choice.” image-8=”” headline-9=”h4″ question-9=”How can you tell PWM from MPPT?” answer-9=”when you buy a solar charge controller, whether is a PWM or MPPT, you can find such specs on the product description, text on boxes and user manuals.” image-9=”” count=”10″ html=”true”]

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