PWM or MPPT: Which Solar Charge Controller Should I Buy?

Are you thinking about going solar, but aren’t sure which type of charge controller to buy? You’re not alone. Many have or are currently grappling with that question. Fortunately, when it comes to makes, models, and types of controllers there’s much to choose from. The problem is that this can make things more difficult. Having so many choices can “muddy the waters,” so to speak, and can make the task of making a decision more difficult. Fortunately, you’ve come to the right place to gain some clarity. In layman terms, I’ll explain in this short article the pros and cons of each type of controller, which makes are best, and what features to look for to ensure that you make the right choice.

Goto KINGSUN to know more.

Simply put, the solar charge controller acts as the “brain” for the solar power system. It harvests and regulates the voltage from the solar panels to prevent your batteries from being overcharged, and in the case of wet cell batteries, boiled dry (note: a charge controller isn’t needed for small 1 to 5 watt trickle charge panels). The solar charge controller provides effective three-stage or four-stage battery charging just like the 110 volt AC battery chargers found in your RVs. Unlike solar panels, which are sized by watt, solar charge controllers are sized by amps with higher amperage models generally costing more. While charge controller features vary by make and manufacturer, there are two primary types of charge controllers used in the industry today: Pulse Width Modulation and Maximum Point Power Tracking. Let’s take a closer look at each.

Pulse Width Modulation (PWM):

A simple, yet proven, time-tested design, the PWM charge controller works by sending a series of short, variable duty cycle charging pulses to the battery–like a very rapid “on-off” switch. The controller constantly checks the state of the battery and automatically adjusts how long the charging pulses will be to the battery. When the battery is fully charged the duty cycle almost falls to zero or “off” nearly 99 percent of the time. Conversely, when the battery is fully discharged, the pulses of the battery stay “on” nearly 99 percent of the time. This controller is generally used in RV solar power systems using 12 volt solar panels wired in parallel.

Strengths of the PWM charge controller design include the fact that it is built on a time-tested and proven technology, is inexpensive–a single unit capable of handling 25 amps can be purchased for less than $100–and is durable. The PWM charge controller comes in various sizes up to 60 amps and can be used in all but the largest systems found in an RV (to give you an idea how large a 60 amp system is, a single 120 watt solar panel generates about 6.5 amps). Most PWM controllers being built today provide three-stage battery charging, though some companies, like Zamp, are touting five-stage battery charging.

While the PWM design is simple and rugged, there are some inherent flaws with the design. For one, the PWM charge controller is less efficient since the controller connects the solar panel to the battery directly. This reduces the voltage developed by the solar panel from the nominal 17 volt output to the battery’s voltage, which lowers the power available from the solar panel. Another flaw with the design is that the pulses generated by the device can create interference in radios and TVs. This is due to the lower frequencies typically used in the PWM charge controller compared to the higher frequencies used in the MPPT controller.

Maximum Power Point Tracking (MPPT):

The newest technology and the latest rage, the MPPT charge controller combines the most effective features of a PWM controller with additional functionality–a PWM controller on steroids, if you will. Instead of connecting the solar panel directly to the battery like a PWM controller, it uses a DC to DC “buck converter” stage before the PWM charging stage. The buck converter ingests the solar panel voltage and transforms it to the optimum battery voltage or “Maximum Power Point.” Secondly, the MPPT charge controller uses an embedded microprocessor driven algorithm to scan or track the solar panel for where the voltage and current are optimized between the solar panel and the battery (the Tracking portion of Maximum Power Point).

The pros of the MPPT charge controller are pretty significant. It harvests at a high-efficiency rate, generally between 94 and 98 percent, and can save considerable money on larger systems since they can provide up to 30 percent more power to the battery in cold weather when solar panels generate their highest voltages. Moreover, the MPPT charge controller is totally compatible with solar panels of various voltages, such as 24 volt and 36 volt models (just make sure all the solar panel sizes and voltages are the same in order for the tracking function to properly work). These higher voltage solar panels can be wired in series or parallel and are generally less expensive per watt than 12 volt models, thus giving you greater flexibility in the panels you can buy. The MPPT charge controller can also be sized up to 80 amps and beyond, providing greater flexibility for system growth. Most MPPT controllers available in today’s market provide four-stage battery charging.

Cons of the MPPT controller include greater cost, two to four times more to a comparably sized PMW controller, and greater physical size. However, the pros associated with the unit’s efficiency and features far outweigh the cons. If you use solar power a significant amount of time throughout the year, and size and cost isn’t an issue, then the MPPT controller is the way to go. If your system is generally small and is used perhaps six to eight times a year on weekend trips, then a PWM controller will more than suffice and will give you years of excellent service.

More Considerations

Now that you’ve chosen the type and style of charge controller, its time to choose the actual make and model. Fortunately, there’s no right or wrong when it comes to the make. Top solar companies include Morningstar, Rogue, and Out Back as well as Blue Sky Energy, Zamp, and Renogy. As for the model, it’s important to size your charge controller for the system you plan on installing in your rig. For example, don’t waste your money on a 60 amp charge controller for a three-panel, 360 watt system that will never generate more than 20 amps of power. Spend that money on something else. However, it’s important not to size your controller too small either. This is especially true if you’re considering adding another panel or two sometime in the future. Always plan for potential future growth when buying your charge controller.

PWM and MPPT solar charge controllers come in two basic styles: flush mount and wall mount. The style that’s best for you is usually determined by how much space you have in your rig and the size of your solar power system. Flush mount PWM and MPPT controllers are typically smaller, are better suited for smaller systems of around 340 watts (20 amps) or less, and are ideal for those situations when space is limited like in a truck camper. On the other hand, if you have a large solar power system, of say, 960 watts (50 amps), and you are planning on installing an MPPT type of controller, then you’ll need to mount it in either a large storage compartment or a large closet because of the controller’s physical size. Whatever you decide, whether it’s a flush mount or wall mount, PWM or MPPT, you’ll want to make sure that the controller is mounted in a location that is dry, has access to wiring, and can easily be viewed and accessed for maintenance.

Unless your rig already has a battery monitoring system like a Trimetric or Xantrex Link+, then it’s absolutely essential to have some kind of digital display meter. The meter allows you to see, at a glance, the voltage state of your batteries and the amperage being generated by your solar panels. This meter can either be on the controller itself, like many flush mount styles, or connected to the controller via an RJ-40 style cable for remote monitoring. Having a remote meter is especially handy for those situations when the controller is wall mounted in a difficult, hard to reach location.

One valuable charge controller feature is the so-called battery temperature sensor. This requires the use of a special wire lead that attaches to both the battery and the controller. This feature automatically adjusts or compensates the charge voltage based upon the temperature of the battery. A cooler battery requires a higher charge voltage whereas a warmer battery requires a lower charge voltage. Applying the proper charge voltage improves battery performance and life, and minimizes battery maintenance. Obviously, this feature is particularly valuable for RVs with outside battery compartments and not so much for those compartments that are found inside.

Solar power systems are growing in popularity, and a key part of these systems is the charge controller. PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracking) are the two primary varieties that rule the market. Although they function differently, these controllers are essential for controlling the energy flow from your solar panels to your batteries. This post will evaluate the advantages and disadvantages of PWM and MPPT controllers and assist you in deciding which could be best for your particular solar setup.

What is PWM Technology?

PWM stands for Pulse Width Modulation. This is one of the methods used in regulating power to the solar panel in the solar charge controller. As a matter of fact, PWM is an electronic method that increases efficiency by switching the power supply on and off at rapid times. So, as technology advanced better than other older charging ways that relied on an ON/OFF power supply, PWM gained a market in the solar systems of the s.

How PWM Charge Controllers Work

PWM controllers match voltage from the solar panels with that of the batteries. The controller will start to pulse the power from the panels once the battery reaches a pre-set voltage. This helps in keeping the battery fully charged without overcharging.

The PWM controllers typically operate on three stages of charging: bulk, absorption, and float. During the bulk stage, the maximum current flows to the battery. In the absorption stage, when the battery reaches near full charge, the current to the battery is decreased. In its final stage, float keeps the charge in the battery at a lower voltage. The controller switches between these stages by adjusting the time spent turned on versus off.

Benefits of PWM Controllers

PWM controllers have several advantages:

• Simple Design: They're reliable and easy to maintain.
• Lower Cost: They're usually cheaper than more advanced controllers.
• Good for Small Systems: They work well in smaller solar setups.

Limitations of PWM Controllers

PWM controllers also have some drawbacks:

Contact us to discuss your requirements of PWM MPPT Charge Controller. Our experienced sales team can help you identify the options that best suit your needs.

• Less Efficient in Changing Conditions: They may not perform as well on cloudy days or in areas with inconsistent sunlight.
• Not Ideal for High Voltage Panels: They're less effective with higher voltage solar panels, which can lead to power loss.

These aspects go hand in glove to establish a basis of carrying out comparisons among various solar charge controllers. A proper understanding of strengths and weaknesses of the PWM technology helps in picking the right controller for particular solar energy requirements.

What is MPPT Technology?

MPPT stands for Maximum Power Point Tracking. It is a high-level technique used by solar charge controllers to obtain maximum power from the solar panels. MPPT controllers are those that are able to continuously adjust themselves in such a way that they constantly extract the maximum available power from the solar panels even when conditions change.

The Maximum Power Point is the voltage and current combination that yields the highest amount of power from a solar panel, and it shifts all day with changing sunlight and temperature. MPPT controllers work to stay at this point for the best energy production.

How MPPT Charge Controllers Work

The MPPT controllers utilize smart computer programs to search and stay at the Maximum Power Point continuously. It adjusts the electrical settings of the solar panels in real time, thereby converting extra voltage into more charging current. Therefore, they can draw more power out of solar panels compared to simpler controllers.

These controllers can work with many different solar panel types. They are able to process higher voltages from panels and convert them to the correct voltage for battery charging. Because of this, MPPT controllers find their applications in everything from home installations to large commercial systems.

Advantages of MPPT Controllers

• More efficient: They often get 20-30% more power from solar panels than simpler controllers.
• Work well in different weather: They can get more power even when it's cloudy or the light is low.
• Flexible for system size: They can handle higher voltages, making it easier to add more solar panels later.

Drawbacks of MPPT Controllers

• More expensive: They cost more to buy at first than simpler controllers.
• More complex: Their advanced features mean they have more complicated parts, which can make fixing problems harder.

The choice between an MPPT and simpler controllers should, therefore, be informed by what your solar system requires, how much you want to spend, and also the kind of performance that you want from such a system. Application of both kinds of controllers would, therefore, depend on what people need and prefer for their solar energy systems.

Which is Better: PWM or MPPT?

Both PWM and MPPT controllers are used in solar power systems. They function a little differently, however.

1. Efficiency in Different Weather

PWM controllers work best during warm, sunny days when the voltage from the solar panels is near the voltage of the battery. MPPT controllers work well during cooler temperatures and when the panel voltage is much higher than battery voltage.

MPPT controllers are able to generate more power from the panels during overcast conditions. They adapt better to changing light than PWM controllers. What this means in practice is that MPPT often produces more energy during a year, especially where the weather is very changeable.

2. Cost and Energy Benefits

PWM controllers are cheaper upfront. They are okay for a very small system on an extremely tight budget. MPPT controllers have a higher upfront cost, but more power comes out of them over time. For bigger systems or those with less hours of sunlight, it may be worth the extra upfront cost for the extra power available with an MPPT system.

Which one to choose between PWM and MPPT is a matter of system size and your budget. Smaller systems in sunny locations may be sufficient with PWM. With larger systems, or in less sunny locations, MPPT will give more advantage.

3. Best Fit for System Size

PWM controllers do an excellent job in small to medium systems, especially when panel voltage is near the battery voltage. They are normally applied in home systems or small off-grid setups.

MPPT controllers are better for big systems. They can handle higher voltages, so you can have more panels or put them far from the batteries. Therefore, MPPT is good to use if systems are large for homes, businesses, or solar farms.

4. Durability and Maintenance

PWM controllers are less complicated and may thus tend to last longer and be easier to repair. MPPT controllers contain more intricate parts and require more careful maintenance. Good quality MPPT controllers, however, are built to last and can be very reliable.

While both can serve for many years if installed and treated accordingly, the ordinary period of their service is of no great significance when choosing between them. It's more about functionality in accordance with the solar system type.

Real-world Uses of PWM and MPPT Controllers

Different solar setups work better with either PWM or MPPT controllers. Here's when to use each type:

When to Use PWM Controllers

• Small home solar systems: Good for setups with a few panels on your roof, powering lights and small appliances.
• Budget-friendly projects: Costs less than MPPT controllers, suitable for simple, low-cost solar setups in sunny areas.

When to Choose MPPT Controllers

• Large commercial installations: Ideal for business or large building solar systems, handling high voltages from many connected panels.
• Areas with challenging light conditions: Better for places with frequent cloudy weather or short winter days, squeezing more power out of available light.

Your choice between PWM and MPPT should consider your system size, budget, and location. Each has its strengths in different situations.

Which to Choose Between PWM and MPPT

Selecting between PWM and MPPT controllers is an important decision for your solar system.

Important Factors to Consider

• System Requirements: Think about the size of your solar setup and what you need it to do. PWM controllers work well for small, simple systems. MPPT controllers are better for larger or more complex setups.
• Location and Weather: Your local climate plays a big role. Sunny areas might do fine with PWM controllers. Places with less sun or changing weather often benefit more from MPPT controllers.
• Cost and Long-term Value: PWM controllers are cheaper to buy at first. MPPT controllers cost more upfront but can save money over time by producing more power. Think about both your current budget and future savings.

Making Your Decision

• List your energy needs and system size.
• Check your local weather patterns.
• Set a budget for both short-term and long-term.
• Compare the features of PWM and MPPT controllers against your needs.

For a small system in a sunny area with a tight budget, PWM might be best. For larger systems, less sunny places, or if you want to get the most energy possible, MPPT is usually better.

Get the Best Solar Controller for Your Needs!

The choice between PWM and MPPT controllers for your solar system would not be a difficult one: PWM works great on small setups, for sunny areas, and is cheaper. MPPT works with bigger systems, well for cloudy areas, getting most of the power out of it. It is, however, much more expensive. Compare your size of the system, your local weather, and how much you can spend. There is no ideal choice for everybody. Choose the right controller according to your situation. This way, your solar system will work great and can provide you with clean energy for several years.

If you want to learn more, please visit our website Waterproof MPPT Charge Controller.