MPPT vs PWM Charge Controllers? How To Choose in 3 Quick Steps (See Chart)

Georgette Kilgore headshot, wearing 8 Billion Trees shirt with forest in the background.Written by Georgette Kilgore

Solar Panels | March 15, 2024

Woman confused, raising her hands while examining mppt vs pwm charge controllers above her head, wondering how to choose between pwm vs mppt charge controllers for solar panel installation for home or rv.

When choosing to install solar panels in your home, whether it’s for a localized energy source (like an AC unit or a electric vehicle), choosing between an MPPT vs PWM charge controller may seem confusing.

However, as an integral part of each photovoltaic system, deciding between charge controllers can mean all the difference in your power output.

Solar charge controllers act as electrical gatekeepers. Though MPPT and PWM solar charge controllers operate differently, both regulate the flow of energy from solar panels to the batteries that they charge.

Although more sophisticated or complex solar charge controllers offer functionality that simplifies monitoring the photovoltaic system, both MPPT charge controllers and PWM charge controllers have notable advantages and drawbacks.

This guide outlines how to choose between MPPT vs PWM charge controllers using 3 quick steps that chart their benefits and drawbacks.

MPPT Vs PWM Charge Controllers

To choose the best charge controller for your specific system, follow these three steps.

Step 1. Ascertain Your Needs

Solar charge controllers should be chosen based on the needs of your system. For example, if the panels will be powering your entire home, that’s considered a large residential application.

However, if you’re using the system to provide energy to a small, one room workshop or RV, efficiency isn’t as important.

Step 2. Consider Your Location

Which charge controller you choose will have a lot to do with where the solar panel system will be located.

If the area gets more than 8 hours of sunlight (average) a day, you may not need a MPPT controller. Whereas if you live in an colder, cloudier region, you will likely need a charge controller that maximizes the sunlight hours.

Step 3. Compare Using the Charts Below

The following charts list the positive and negative sides to each charge controller based on a number of factors.

PWM Charge Controllers

Pros Cons
Low Cost Batteries and System must have matching voltages
Perfect for smaller systems (RV’s, one room) Not suitable for larger systems
Less moving parts Not as Efficient
Longer lifespan
Works best in sunny, warm regions


Pros Cons
More efficient on cloudy days Higher Cost
Better for larger systems (full residential) Shorter lifespan
Solar array voltage can be higher than battery More components
Best for low charge state batteries (adaptable)
Best for colder, less sunlight hour locations

Types of Solar Charge Controllers: MPPT vs PWM as Primary Options

The two most prevalent types of solar charge controllers are maximum power point tracking (MPPT) and pulse width modulation (PMW).

Shunt charge controllers and series charge controllers are also available, though their low energy efficiency limits their practicality.

It cannot be overemphasized that different manufacturers and models can make solar charge controllers vary significantly.

This is to say that not all MPPT charge controllers are alike, nor are all PWM controllers the same.

MPPT Meaning: Definition of MPPT

The term MPPT is an acronym for “maximum power point tracking.”

MPPT charge controllers adjust a solar power system’s impedance, alternately called the load characteristic, in response to factors that change the efficiency of transferring power from the solar panels to their destinations.

The MPPT meaning derives from the maximum power point, which is the most efficient impedance which yields maximum energy transfer.1

What Is a PWM Controller?

PWM is an acronym for “pulse width modulation.” Pulse width modulation is analogous to a power switch that can turn on and turn off within milliseconds.

To protect charging batteries from excess voltage, PWM controllers shut down and restart the solar panels to which they are connected rapidly, reacting to voltage-changing changes in direct and indirect light.

A simplistic answer to “What is a PWM Controller?” is a high-speed, rapid-fire electric switch. Its ability to switch off within a few milliseconds is what makes the switching a viable and effective option.


MPPT charge controllers are a good selection for large-scale solar power collection systems. MPPT is also a good option for solar power operators whose panels have a maximum power voltage above 18 volts.

Solar panel operators deciding between MPPT vs PWM should choose MPPT for systems where energy efficiency and high volumes of energy are a critical or high priority. MPPT charge controllers also allow solar panel operators flexibility when pairing controllers with batteries.

The array voltage of PWM charge controllers must match the voltage of the batteries that they charge for optimal operations. MPPT charge controllers, however, can have an array voltage that is higher than the batteries to which they will be connected.

Since MPPT charge controllers have higher average energy efficiencies than PWT charge controllers, solar panel operators with limited space for solar panels should favor MPPT vs PWM. The high energy capture rates of MPPT charge controllers will allow solar panel operators to make the most use of their space restrictions.

PWM vs MPPT Charge Controllers

PWM charge controllers are a sound economical option for small or underdeveloped solar power collection systems.

Solar panel operators torn between PWM vs MPPT should consider the former when the maximum power voltage of their solar panels is under 18 volts or where efficiency is not a critical or high priority.

The climate where the charge controllers will operate is an important factor when choosing between PWM vs MPPT charge controllers. MPPT controllers can charge batteries faster when they operate at cooler temperatures.

When the temperature rises, the MPPT controllers stop collecting the excess energy, which could make PWM charge controllers a cheaper and equally-effective alternative for solar panel operators in warm and hot climates.

Solar Charge Regulator vs Controller

There is no difference between solar charge regulator vs controller.

They refer to the exact same type of device, so the two terms are synonymous.

How To Wire Solar Panels

It is advisable to hire certified or trained professionals to set up solar panels. They have the tools and experience regarding how to wire solar panels safely and effectively.

The two most common methods of wiring solar panels together are series and parallel.

Series wiring has a simpler setup, though the current generated is the same as the lowest current among the individual panels.

A worker connecting wires underneath a solar panel.

(Image: Chrischesneau7)

Parallel wiring is more complex to set up properly, but its current is unchanged when one of the solar panels yields a low current. The series method of wiring solar panels connects solar panels together one line at a time.

Series wiring involves connecting the positive terminal of a solar panel to the negative terminal of a neighboring panel. The terminals of the solar charge regulator are connected to the negative terminal of the first panel and the positive terminal of the second panel.

Parallel stringing focuses on connecting one wire to the positive terminals of all the solar panels and a second wire to all the negative terminals of the solar panels.

The terminals of the solar charge regulator are connected to the dedicated positive wire and the dedicated negative wire.

Regarding MPPT vs PWM, solar panel operators wiring multiple solar panels together are advised to favor MPPT.

Since multiple panels will face several factors causing their energy output to fluctuate, tracking and responding to the maximum power point will be more effective than rapid-fire deactivation and reactivation.

How To Test a Solar Panel

Many modern solar charge controllers have built-in functionality which simplifies how to test a solar panel.

Solar charge controllers with functionality like Bluetooth compatibility or clear LCD displays can provide solar panel operators with real-time information.

Solar panel operators fortunate enough to have a solar charge controller with monitoring tools can connect a battery and a solar panel to their solar charge controller.

Sophisticated monitoring tools can tell solar panel operators the watts that the solar panel yields.6

If the wattage is not directly available, solar panel operators can calculate it by accessing the PV voltage and the PV current, then multiplying the two values.

A working on the roof as it tests the solar panels if they are working.

(Image: Trinh Tran8)

Solar panel operators can also use a multimeter to test their solar panels. The process of using multimeters to test solar panels is not simple, but multimeters allow solar panel operators to determine a solar panel’s open circuit voltage, short circuit current, and operating current.

This method requires solar panel operators to compare the data they collect with the manufacturer-provided specifications, which are often found on a label on the back of the solar panel. You can also use a watt meter to determine the watt output of a solar panel.

This involves connecting a solar charge controller to a battery, then to the watt controller, then finally to the solar panel being tested. The watt meter will display the watts that the solar panel yields.

Charging Tesla With Solar Panels

Charging Tesla with solar panels is possible, though this requires acquiring additional tools.

Specifically, Tesla owners will need to purchase additional solar panels to compensate for the additional electricity usage, battery packs to facilitate charging during the night or indirect light, and a charging point to which to attach the car.

Knowing how many solar panels are needed to fully charge a Tesla is essential to ensure that charging the Tesla doesn’t overburden the photovoltaic system or render it carbon-negative.

Carbon Footprint Solar Panels

Though solar power is more environmentally friendly, the carbon footprint solar panels is four times larger than the carbon footprint of nuclear power.

Solar power still has a smaller carbon footprint than fossil fuels, but solar power does pose problems that, if left unchecked, can undercut or negate its benefits.

The most carbon-unfriendly aspect of solar power lies within the processes used in manufacturing and maintaining solar panels and related infrastructure. Depending on the type and efficiency of the solar panels, a photovoltaic system can take approximately four years to offset the carbon dioxide released and energy spent in creating the solar panels.2

Complicating matters further is that expired or irreparable solar panels that contain toxic components such as cadmium or lead are hazardous waste and require special handling to safely recycle or process.3,5

Turning a photovoltaic system into a net positive for reducing carbon footprint solar panels requires planning and long-term investments.

And solar power is only one part of a comprehensive solution to the climate change crisis; other vital measures include planting new trees and drastically reducing our global, industrial, and individual carbon footprints.

How Much Power Does a Solar Panel Produce?

When asking how much power does a solar panel produce, know that an individual photovoltaic cell generates roughly 0.5 volts and between 1 and 2 amps.4

However, since solar panel manufacturers create solar panels with varying cell counts and underlying technology that can vary the solar panel’s operations and output, there is no singular answer to how much power does a solar panel produce.

Solar panel operators can generate a reasonable estimate by using the number of cells to calculate the estimated voltage, then multiplying that by the amperage to estimate the wattage. An estimate for a 60-cell solar panel would be 30 volts and between 1 and 2 amps, yielding a range between 30 and 60 watts.

The most effective way to determine how much power does a solar panel produce is to test the solar panel with a solar charge controller, a multimeter, or a watt meter.

Comparing these values with the manufacturer’s specifications will give indicators of the panel’s effectiveness and operability.

What Size Solar Panel To Charge 100Ah Battery?

The number of factors that govern battery charging means that there is no uniform answer to what size solar panel to charge 100ah battery.

The remaining charge in the battery, the battery voltage, the battery type, the battery depth of discharge, the solar charge controller type, the desired charge time, the number of hours in peak sun time, and the manufacturer-driven differences in solar panels means that even two solar panels of the same size may have different charging results.

A small 12v batter being used to charge a device.

(Image: Newpowa9)

One could argue that what size solar panel to charge 100ah battery is a trick question. Often, charging a 100ah battery within a reasonable amount of time requires multiple solar panels.

Also, solar panel operators will have to choose between mppt vs pwm charge controllers, deciding whether the higher efficiency of MPPT is more important than the simplicity and lower cost of PVM.

How Many MPPT Do I Need?

One MPPT solar charge controller is sufficient for most photovoltaic systems. The question how many mppt do I need becomes relevant only when the photovoltaic system becomes large (i.e. a high number of solar panels) or complex (i.e. varying voltages and amperages).

Setting up a photovoltaic system can be complex. And even the best-maintained and high-efficiency photovoltaic systems can take years to offset the carbon dioxide emitted and energy spent in manufacturing the components that make up the system.

An image that shows the examples of building-integrated and ancillary structure photovoltaic applications of roof awning, facade, balustrade, window, and shade canopy.

(Image: Solar Energy Technologies Office10)

Complicating matters further is that there is no one-size-fits-all approach; a solar panel operator that wants to charge their RV battery will need different equipment than a solar panel operator installing solar panels on their corporate headquarters as part of a green energy initiative.

Solar charge controllers protect the components to which they are attached while increasing the efficiency of the energy that is passed from the solar panels to the batteries or other energy repositories.

But not only are there significant differences between MPPT vs PWM, the number of manufacturers and models means that there are several significant differences between charge controllers of the same type.

There are no easy answers, but there are guidelines. PVM charge controllers are a good choice for small, simple photovoltaic systems and for systems that do not generate large amounts of power.

MPPT controllers are a preferable option for large, complex photovoltaic systems and systems that generate large quantities of power.

Understanding your goals, restrictions, and the budgets that govern your photovoltaic systems provides the best and only way to make the correct decision between MPPT vs PWM.


1Wikipedia. (2023, February 12). Maximum power point tracking. Wikipedia. Retrieved March 10, 2023, from <>

2PV FAQs. Washington, D.C.: U.S. Department of Energy. Retrieved March 10, 2023, from <>

3The National Renewable Energy Laboratory. (2022, August 28). End-of-Life Solar Panels: Regulations and Management. United States Environmental Protection Agency. Retrieved March 10, 2023, from <>

4Arizona State University. (2023). How Solar Works. Business and Finance. Retrieved March 10, 2023, from <>

5National Center for Biotechnology Information. (2020, October 13). Cadmium and Lead Exposure, Nephrotoxicity, and Mortality. National Library of Medicine. Retrieved March 16, 2023, from <>

6US Department of Energy. (2023). Electric Meters. Energy Saver. Retrieved March 16, 2023, from <>

7chrischesneau. Pixabay. Retrieved from <>

8Trinh Tran. Pexels. Retrieved from <>

9Newpowa. Unsplash. Retrieved from <>

10Solar Energy Technologies Office. US Department of Energy. Retrieved from <>