PWM vs MPPT

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PWM technology has reached the end of its rope. Or has it?  MPPT is the only way when going solar. Is that really true? 

When we talk about PWM vs MPPT, it comes down to the method of powering a solar panel. It depends on whether the solar panel is in parallel or in series with the system. In the former case, it is called the PWM or Pulse-Width Modulation technique, and in the latter case it is called the MPPT or Maximum Power Point Tracking technique.

Each method has some advantages and disadvantages, but is one method really better than the other? 

This review article will help you find out the truth behind both methods and which is better for you. We review products day in and day out. Our readers appreciate our honest perspective and we value their loyalty. 

What Are the Significant Differences Between MPPT and PWM?

PWM DC Motor Speed Controller, DC 10-55V/60A, LED Display Stepless DC Motor Speed Controller with Adjustable Potentiometer and Forward-Brake-Reverse Switch

Renogy Rover 40 Amp 12V/24V DC Input MPPT Solar Charge Controller Auto Parameter Adjustable LCD Display Solar Panel Regulator fit for Gel Sealed Flooded and Lithium Battery

What is MPPT?

MPPT (Maximum Power Point Tracking) is a technique that attempts to optimize the charging algorithms to extract the maximum power from a solar panel by placing the solar panel in the sun at the optimal angle to maximize its output.

What is PWM? 

PWM stands for Pulse Width Modulation and is a technique used in traditional solar panels. In PWM, the solar panels are connected to a controller. The controller detects the sun’s elevation and sets the panels’ output (voltage) accordingly. 

MPPT vs PWM: Comparison

Temperature Conditions

PWM has a much better tolerance for high temperatures than MPPT, but it can’t reroute additional voltage. MPPT wins in the cooler temperature range plus it has the ability to route additional voltage. 

Array to Load Ratio

Both PWM and MPPT can produce more power without increasing load, but PWM does this at a lower cost than MPPT can.

Size of the System

PWM systems are hands down more suited to low power solar systems. Their price point and efficiency are acceptable for the type of equipment it is. But MPPT can handle larger solar set ups.

Type of Solar Module

Both PWM and MPPT systems are compatible with nearly any solar equipment. MPPT shines in this area because its technology is able to determine exactly what a system needs and charge it with no problems. 

Cost

If this were just a pure monetary comparison then PWM wins by a mile. It simply is a much less expensive option over MPPT. But in the end you get what you pay for.

With MPPT, even though the initial costs are more than PWM, you get a wide range of technologies that let you take full advantage of what solar charging should really be like. 

MPPT vs PWM: Charge Differences

PMW 3 Stage Charging

Bulk Charge

Solar chargers inherently use bulk charging, which is a method of charging that uses a solar panel to charge a battery from a larger source of power.

Absorb Charge

This method will allow a battery to fully charge to a preset level. Even if the battery is left plugged in, it will keep whatever preset voltage is allowed until it’s needed. 

Also Read: Best Solar Charge Controller in 2021

Float Charge

When a battery is fully charged, it has a high voltage with a relatively small current. At this point, the battery is known as float charge. The battery will hold this voltage even if the charger is not connected or if the charger is not turned on. 

MPPT Multi-Stage Charging

MPPT systems also use bulk, absorb and float charging, but at a much higher efficiency rate versus PWM. The main difference is that MPPT uses sophisticated algorithms combined with top notch technology to handle those charging methods. 

In addition, MPPT uses one more charging method called Balance charge. It’s also known as boost charge. 

Balance Charge / Boost Charge

Boost charging  is designed to capture as much of the photo-voltaic energy from the sun as possible. Typical solar chargers are characterized by their ability to work with different PV modules. MPPT boost charging can charge more than one type of solar panel at the same time.

MPPT vs PWM Solar Charger: Application

MPPT Charger Pros

  • At least a 30% charging efficiency over PWM
  • More generous warranties
  • Grid connect modules can only be controlled through MPPT

MPPT Charger Cons

  • Difficult to maintain efficiency in very high temperatures
  • Solar panel / array has to be configured in a specific way

PWM Solar Charger Pros

  • Extremely reliable
  • Very little maintenance has to be performed as they are very rugged
  • Much less expensive versus MPPT

PWM Solar Charger Cons

  • Capacity limits, you can only grow your system so far
  • Some PWM controllers are not UL listed
  • The voltage from the battery bank has to match the voltage from the controller

MPPT vs PWM Charging Technology: MPPT Advantages

PWM definitely still has its uses, but it’ll never be able to catch up to MPPT due to how technology is always advancing. MPPT is more flexible and able to charge more systems than PWM. 

MPPT is also able to grow in scale farther than its predecessor thanks to its ability to produce more AMPS than PWM.  The MPPT controller is able to sense your system, scan it, adjust for efficiency and start charging within a few seconds. PWM doesn’t have the technology for this.

Conclusion – MPPT Is Worth Every Cent

We really hope you enjoyed our review about PWM vs MPPT. In the end, we feel MPPT will be the best choice for solar charging no matter the situation. 

PWM has its advantages, but there’s not enough reason besides price to consider PWM when the technology is not there to support the cost. MPPT wins.

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