What is a solar charge controller and why are they important?
As the name suggests, a solar charge controller is a component of a solar panel system that controls the charging of a battery bank. Solar charge controllers ensure the batteries are charged at the proper rate and to the proper level. Without a charge controller, batteries can be damaged by incoming power, and could also leak power back to the solar panels when the sun isn’t shining.
Solar charge controllers have a simple job, but it’s important to learn about the two main types, how they work, and how to pair them with solar panels and batteries. Armed with that knowledge, you’ll be one step closer to building an off-grid solar system!
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Key takeaways
- Solar charge controllers allow batteries to safely charge and discharge using the output of solar panels.
- A charge controller is needed any time a battery will be connected to the direct current (DC) output of solar panels; most often in small off-grid systems.
- The two kinds of charge controllers are pulse-width modulation (PWM) and maximum power point tracking (MPPT).
- PWM charge controllers are less expensive, but less efficient, and are best suited for small off-grid systems with a few solar panels and batteries.
- MPPT charge controllers are more expensive and more efficient, and are good for larger off-grid systems that can power a small home or cabin.
- The top off-grid charge controllers are made by brands like Victron, EPEVER, and Renogy, but non-brand-name charge controllers can be just fine if you know what to look for.
Who needs a solar charge controller?
A charge controller is necessary any time a battery bank will be connected to the direct current (DC) output of solar panels. In most cases, this means a small off-grid setup like solar panels on an RV or cabin. If you’re looking for information on how to use solar and batteries off the grid, you’re in the right place!
There are also charge controllers aimed at providing battery backup for an existing grid-tied solar system that is on the roof of a home or business. This application requires a high-voltage charge controller and usually involves rewiring the system to direct a portion of the solar output through the charge controller.
How does a solar charge controller work?
Fair warning before we get started: we’re about to discuss voltage, amperage, and wattage. If you need a refresher on how these things work together, check out our article on watts, kilowatts, and kilowatt-hours.
A solar charge controller is connected between solar panels and batteries to ensure power from the panels reaches the battery safely and effectively. The battery feeds into an inverter that changes the DC power into AC to run appliances (aka loads).
How a charge controller works within an off-grid solar system.
The four main functions of a solar charge controller are:
- Accept incoming power from solar panels
- Control the amount of power sent to the battery
- Monitor the voltage of the battery to prevent overcharging
- Allow power to flow only from the solar panels to the batteries
As a battery charges, its voltage increases, up to a limit. The battery can be damaged if an additional charge is applied past this limit. Therefore, the ability of a battery to provide or accept power can be measured by its voltage. For example, a typical 12-volt AGM lead-acid battery will show a voltage of 11.8 volts at 10% charged to 12.9 volts at 100% charge.
The main function of a solar charge controller is to ensure the amount of power that is sent to the battery is enough to charge it, but not so much that it increases the battery voltage above a safe level. It does this by reading the voltage of the battery and calculating how much additional energy is required to fully charge the battery.
Another important function of the charge controller is to prevent current from traveling back into the solar panels. When the sun isn’t shining, the solar panels aren’t producing any voltage. Because electricity flows from high voltage to low voltage, the power in the battery would flow into the solar panels if there was nothing in place to stop it. This could potentially cause damage. The charge controller has a diode that allows power to flow in one direction, preventing electricity from feeding back into the panels.
How solar power gets from panels to batteries
As we mentioned above, power flows from high voltage to low. So, to add energy to the battery, the output voltage of a solar panel must always be a little higher than the voltage of the battery it’s charging. Thankfully, solar panels are designed to put out more voltage than a battery needs at any given time.
Here’s an example: Say you have a single 100-watt solar panel and a 12-volt battery. Remember from above that a 12-volt battery is actually able to charge up to about 12.9 volts. 12 volts is what is called its “nominal voltage,” while the actual voltage of the battery depends on how charged it is. It might sink to 11.8 volts at low charge, and 12.9 volts when full.
The 100-watt solar panel can put out a maximum of 18 volts, which is a little too high for the battery to accept safely. Leaving it connected to the battery too long could result in a dangerous situation, eventually causing pressure to build up inside the battery and vent out the side as chemical steam.
You need a charge controller in between the solar panel and the battery to limit the voltage available to the battery. But it’s not just about the voltage. it also has to withstand a certain amount of current (amperage) flowing through it. That’s where the amperage rating of the charge controller comes in.
Charge controller amperage rating
The number of amps of current a charge controller can handle is called its “rating.” Exceeding the amperage rating can cause damage to the wiring within the charge controller. Let’s consider a charge controller rated to handle 30 amps of current. The single 100- watt solar panel described above puts out 5.5 amps of current at 18 volts. That amperage is much lower than the charge controller’s maximum of 30 amps, so the charge controller can easily handle the output of the singular solar panel.
In fact, it could handle the output of multiple solar panels wired in parallel (which increases current output). But there’s an important rule about charge controller ratings to consider: always make sure your charge controller is rated to handle 25% more amps than your solar panels are supposed to put out. That’s because solar panels can exceed their rated current output under especially bright sun, and you don’t want to fry your charge controller on the rare occasion when that happens.
Keeping that rule in mind, the 30-amp charge controller in our example could accept a nominal output of up to 24 amps. You could wire as many as four of those 5.5-amp solar panels in parallel to create a solar array capable of putting out 22 amps, staying under the charge controller’s rating plus the 25% cushion. If you think you might expand the size of your solar array in the future, get a charge controller rated for 50% more amps than your immediate needs.
Matching voltages
Another consideration when choosing a charge controller is the voltage of the battery bank you want to charge. Wiring batteries in series increases the voltage they can deliver and accept. For example, two 12-volt batteries wired in series will operate at 24 nominal volts. There are charge controllers on the market that can pair with battery banks of 12, 24, 36, and 48 volts. You need to make sure the charge controller you purchase can pair with the voltage of the battery bank.
Battery charging stages
There are three stages of charging a battery: bulk, absorption, and float. They correspond to how full the battery is.
- Bulk: When a battery charge is low, the charge controller can safely push a lot of energy to it, and the battery fills up with charge very quickly.
- Absorption: as the battery nears its full charge (around 90%), the charge controller reduces its current output, and the battery charges more slowly until it’s full.
- Float: when the battery is full, the charge controller lowers its output voltage just a bit to maintain the full charge.
Think of it like pouring water from a pitcher into a cup with a very slow leak: when the cup is empty, you start pouring and quickly increase the amount of water being poured until the cup is nearly full. Then you reduce the flow until the cup is full. In order to keep the cup full despite the leak, you pour just a trickle to keep it topped off.
The bulk/absorption/float process was developed for lead-acid deep cycle batteries. Some newer lithium batteries allow for higher current up until they’re quite full, meaning a charge controller paired with a lithium battery can be set to shorten or eliminate the absorption stage.
Types of charge controller
There are two main ways to control the flow of power to a battery, and they correspond to the two types of charge controller: pulse-width modulation (PWM) and maximum power point tracking (MPPT).
Pulse-width modulation (PWM)
Pulse-width modulation is the simplest and cheapest automatic way to control the flow of power between solar panels and a battery. There are PWM charge controllers on the market for between about 15 to 40.
A PWM charge controller ensures the battery never charges to more than its maximum voltage by switching the power flow on and off hundreds of times per second (i.e. sending “pulses” of power) to reduce the average voltage coming from the solar panels. The width of the pulses reduces the average output voltage.
Here’s an image to illustrate how the pulses work:
For example, if the charge controller accepts 18 volts from the solar panel, it might adjust the pulses so they’re on 82% of the time, and off 18% of the time. This would reduce the average voltage by 18%, down to about 14.8 volts, which can be used to charge a half-full AGM battery. As the battery gets close to a full charge, a PWM charge controller shortens the pulses even further, down to around 77% of the time, or 13.8 volts, to prevent the battery from overcharging.
Unfortunately, the excess energy produced by solar panels is wasted to reduce the output voltage. In our example, the charge controller would average around 80% efficiency. This means it’s very important to make sure the output voltage of the solar panels is not too much higher than the voltage of your battery bank with a PWM charge controller to minimize wasted energy. If your solar array outputs a much higher voltage, the PWM charge controller will cut that voltage down to what the battery can accept, and waste the rest.
Something like 80% efficiency is fine for small off-grid applications like a few solar panels hooked up to a couple of batteries, especially at the low cost of a PWM charge controller. For larger systems with much higher output, it is generally preferable to use the other kind of charge controller technology known as maximum power point tracking, or MPPT.
Maximum power point tracking (MPPT)
An MPPT solar charge controller operates by converting the incoming power from solar panels to match the theoretical highest-efficiency output at the right input voltage for the battery. The charge controller does this by calculating the point at which the maximum current can flow at a voltage the battery can accept, then converting the solar panel output to that mixture of voltage and current.
The major advantages of MPPT charge controllers are greater efficiency and compatibility with higher voltage solar arrays. This means that you can charge a 12V battery bank with a larger solar array wired in series, as long as you stay within the limits of the controller’s amperage rating. You can calculate this limit by taking the total wattage of the solar array and dividing it by the voltage of the battery bank to get the maximum possible output in amps.
Let’s use the same example numbers as before. The solar panel is putting out 100 watts, or about 5.5 amps into 18 volts. The MPPT charge controller converts the output to 14.8 volts but loses about 5% of the power in the conversion process. So the MPPT controller’s output current is about 6.4 amps, times the 14.8 volts, or 95 watts.
Theoretically, in an hour of full sun, the MPPT charge controller will have delivered 95 amp-hours of energy to the batteries, compared to the PWM charge controller’s energy output of about 80 amp-hours. In practice, it isn’t quite that simple, as solar pro Will Prowse discovered in this video:
Common features and settings on a charge controller
The basic features of the simplest PWM charge controller include the ability to set the type of battery and battery bank voltage, and lights indicating the phase of charging (bulk, absorption, and float). advanced PWM and MPPT models come with a small LCD display for programming and data display, a heat sensor port to monitor battery temperature, and a communications port to connect the charge controller to an external display or computer. The most advanced charge controllers offer Bluetooth connectivity and an app for customizing settings.
Recommended prodcuts
There are tons of fine charge controllers available on the market. Search any solar supply or online marketplace like Amazon and you’re bound to turn up dozens of results.
The cheapest PWM charge controllers can be had for around 15, and are often rebranded versions of the same design. These lack many features but are relatively reliable for how inexpensive they are. expensive PWM charge controllers built with better quality materials can be had for under 50, while full-featured MPPT charge controllers are priced anywhere from 100 to 200.
Below are a few of our recommended charge controllers at different price points for a medium-sized off-grid setup.
Renogy Wanderer 30A 12V PWM
The Renogy Wanderer 30A PWM charge controller is a solid choice for a smaller off-grid setup. It can handle up to 30A of current at 12V, so it’s not meant for a large system.
It doesn’t have a screen, but it does pair with the three main kinds of lead-acid batteries as well as lithium ones. It has a connector port for an optional temperature sensor and includes an RS232 port that can be used to program the charge controller or even to add Renogy’s BT-1 Bluetooth module for connecting to the Renogy app on your smartphone.
The Wanderer can be had for about 40 from Amazon or Renogy direct.
EPEVER Tracer BN 30A 12V/24V MPPT
The EPEVER Tracer BN MPPT 30A charge controller is not the cheapest MPPT charge controller on the market, but it’s a very good one. With a die-cast aluminum body, sturdy connectors, and a DC output to power loads like DC appliances or LED lights, the Tracer BN is a robust piece of equipment perfect for handling solar charging of lead-acid batteries in 12- and 24-volt banks. It can accept an incoming power output of up to 2,340 watts of solar panels (that’s equal to three parallel strings of four 60-cell solar panels wired in series). The Tracer can be programmed to charge lithium batteries, but it doesn’t come with a preset charging profile for them.
This EPEVER Tracer BN kit at Amazon includes a temperature sensor, mounting hardware, and a separate screen for programming and monitoring the health and state of charge of your battery system. Price at the time of publishing was 179.99.
Victron Energy SmartSolar 30A 100V MPPT
Victron is one of the most trusted solar brands in the world, and its technology is now becoming more widely available in the United States. This 30A, 100V charge controller is known as one of the best on market. Just like the EPEVER controller, it works with 12- or 24-volt battery banks but allows for slightly lower voltage solar input. To stay under this charger’s rating, you could run as many as three parallel strings of three 60-cell solar panels in series to achieve an output of 90 volts at around 20 amps (1,800 watts of solar output).
It’s made with quality components, calculates maximum power point quickly and with high efficiency, and is very easy to use. The SmartSolar line of charge controllers all come with Bluetooth connectivity on board and can connect to the VictronConnect app on Android, iOS, macOS, and Windows for easy programming. Perhaps most importantly, you get a 5-year limited warranty that protects you against defects in materials and workmanship.
The SmartSolar 30A is the most expensive product on our list at around 225 on Amazon, but reading the reviews from its users, you can see why the expense might be worth it.
Solar charge controllers: are they right for you?
All the information above should give you a good basis of knowledge about how solar charge controllers work and how to pair them with solar panels and batteries, but there’s no substitute for practical, hands-on experience! If you have a few bucks to spend, you can set up a pretty simple off-grid solar “generator” using a single solar panel, a charge controller, a battery, and a cheap inverter. Choosing a charge controller that’s oversized for a small application gives you a chance to increase the size of the solar array and battery bank as you gain experience or find new ways to use the stored solar energy.
Now go out there and start making solar and batteries work for you!
Solar Charge Controllers: Guide for Beginners
When learning about solar power one of the first things most realize is that solar power cannot be used directly. Because of its fluctuations throughout the day and weather conditions, solar power is not constant and requires some electronics to control it. When using solar to charge batteries they cannot be connected directly and need a solar charge controller installed.
So let’s shine a light on this device and what solar owners need to know when picking one.
Table of contents
- Pulse Width Modulation (PWM)
- Maximum Power Point Tracking (MPPT)
- Prevents Overcharging
- Prevents Reverse Currents
- Budget
- Equipment Quality
- Size
- Programming Capabilities
- PWM
- MPPT
What Does a Solar Charge Controller Do?
Solar charge controllers are always needed in systems that have batteries. Battle Born’s lithium battery line is an excellent choice for solar energy storage, but a solar charge controller is needed to hook up panels.
To understand what solar charge controllers do and why they’re critical to any solar power system, we should start with the solar panels themselves. Solar panels generate power when light shines on them, but they have no internal control over their power. Frequently, a solar panel will generate a voltage much higher than what a battery can handle and they will not stop producing power when batteries are full. Both of these conditions can severely damage a battery.
To prevent this, solar charge controllers regulate the flow of electricity from the panels. Solar charge controllers feed electricity to the batteries at the proper voltage until they’ve reached an optimal level and then close off the flow.
A charge controller also helps prevent power from flowing back to the solar panels. While most panels have diodes that prevent this, some power can “leak” back to the panels at night. So they’re like a traffic cop, ensuring the flow of electricity goes in the correct direction in the right volume at the right time.
How Does a Solar Charge Controller Work?
Now that you know what solar charge controllers do, we can dive into how exactly they do it. There are two main types that function in different ways: the pulse width modulation (PWM) and the more advanced maximum power point tracking (MPPT).
Pulse Width Modulation (PWM)
Pulse Width Modulation is like an electronic switch that sits between the solar panels and batteries. This switch can quickly move on and off to control the flow of electricity based on the voltage in the batteries.
Typically, they operate by slowly reducing the strength of the charge as the batteries fill up until eventually closing it off entirely when fully charged. They’ll work best in sunny climates where solar energy generation is relatively constant.
PWM charge controllers can not control voltage well because all they do is switch power on and off. Because of this you need to run solar panels that are closely matched to the battery’s voltage.
This is an older, more standard technology. It is less costly than MPPT controllers and may also have a longer lifespan in many cases.
Maximum Power Point Tracking (MPPT)
Maximum Power Point Tracking (MPPT) solar charge controllers have much more sophisticated technology within them. They are basically DC-DC converters that have the capability to change the voltage and current of the output. This enables much more flexibility with running higher voltage solar panels or a series setup.
MPPT’s are designed with efficiency in mind. Since solar panels produce different levels of energy from day to day and hour to hour depending on weather and other conditions, MPPT technology tweaks the voltage and current from the panels as it regulates the energy flow. This helps keep the solar panels operating in their most efficient power range depending on the conditions and can improve output by up to 30% over a PWM model.
This can dramatically increase power output in charging, something especially critical for large systems or entirely off-grid homes. The higher voltages from the solar panels also allow for less loss in lines to the solar panels and longer runs are possible. MPPT units are generally more expensive than PWM controllers, they’ll work better in most situations.
Solar Charge Controller Features
As you can see, solar charge controllers are a crucial part of any solar power system. Here’s a closer look at some of the most significant benefits of this humble piece of technology.
Maintains Charge
A solar charge controller can maintain a charge on the batteries even if they are being used. If batteries are full, the power used will flow directly through the charge controller and not discharge the battery.
Solar charge controllers also can maintain a healthy battery charge even if the system is not being used so that the batteries are ready to go next time they are needed.
Prevents Overcharging
Again, solar panels simply feed electricity as long as they generate it from the sun. In many locations, this will lead to overcharging long before the sun goes down. Solar charge controllers monitor charge levels in batteries to prevent overcharging. This can save you hundreds of dollars in replacement batteries and countless hours of frustration or annoyance.
Prevents Reverse Currents
One of the main functions of a solar charge controller is to close off the flow of electricity between the panels and batteries. This closed-off connection works both ways. At night, solar charge controllers prevent energy from flowing out of the batteries back toward the panels. These reverse currents don’t only leave batteries drained. They can also seriously damage panels, leaving them operating at reduced efficiency.
Do You Need a Solar Charge Controller?
The answer to this question is a resounding yes. Solar charge controllers are just as integral a part of a solar power system as the panels and batteries. In fact, both of these other components wouldn’t function properly and may even face permanent damage without the work of solar charge controllers. This damage could even lead to potentially unsafe situations for owners.
However, you can avoid all of this using a simple, relatively affordable solar charge controller. Along with its other valuable features, solar charge controllers can help keep your system humming for years to come.
100Ah 12V LiFePO4 Deep Cycle Battery
Prevent the overcharging of batteries and maximize energy from the sun with these regulating solar devices.
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When installing off-grid solar power, a solar charge controller (or solar regulator) will function as the brain of your solar system. This necessary device connects the solar panels to the batteries, so as energy is produced from sunlight, a controller regulates this flow to prevent the panels from overcharging the batteries.
By monitoring high and variable voltage, the charge controller also protects your batteries from damage and even fires. Whether you’re installing solar power in your tiny home, shed or off-grid cabin, or are using it to power backyard lighting and water-pumping applications. a solar controller is an integral piece of your renewable energy system. A high-quality controller will help to maximize the efficiency of your panels so less energy is wasted.
We’ve sorted through many types of controllers that are available from top-rated companies, and present the best solar charge controllers to meet your system’s needs and your budget.
- BEST OVERALL:DIY Solar For U Sól Buck Boost 20 Amp MPPT
- BEST BANG FOR THE BUCK:WindyNation TrakMax 40 Amp MPPT
- BEST WATERPROOF:Renogy Voyager 10 Amp PWM
- BEST 30 AMP:Victron Energy SmartSolar 30 Amp MPPT
- BEST 60 AMP:Renogy Rover 60 Amp MPPT
What to Look For When Choosing the Best Solar Charge Controller
Off-grid solar power systems have four major components : a solar panel for collecting energy. a charge controller for regulating it, a battery for storage, and an inverter for use. If a solar controller is the missing part of this equation to install your system, there are several things to consider before purchasing one.
Size
The size of the solar charge controller will depend on how many watts you need to collect from the sun. To calculate the current capacity required, figure out how many amps your system normally produces and add 25 percent to account for temporary increases in current levels. When in doubt, it’s always better to go too big than too small. Using a solar charge controller with too few amps can negatively affect the system, but using a controller that’s larger than you need will not cause any issues.
Type
The charge controller’s technology is available in two options: pulse width modulation ( PWM) and maximum power point tracker ( MPPT). A PWM controller works by establishing a direct connection between the solar panels and the battery. On the other hand, MPPT controllers measure the solar panel’s voltage which is then down-converted to match the battery’s voltage, helping to increase the current.
Batteries
It’s important to consider what type of battery you’ll be charging. Whether it’s lead acid, sealed lead acid (AGM and Gel), or lithium-ion, you’ll want to ensure that the solar charge controller is compatible in order for the controller to function.
Added Features
There are several additional features that can enhance a solar controller and add convenience for the user. For example, multi-voltage function-enabled controllers let you adjust the charging voltage set point so the device operates more effectively. Or, if you’re willing to pay a little extra, some controllers have remote access so you can control the device from any location.
Load control is another important feature to look for, and refers to the ability to turn off your battery’s output when the charge controller senses the battery bank is too low. Most charge controllers have this function, so it’s mostly a matter of whether you want a controller with automatic load control or if you prefer to do it manually.
Lastly, it’s essential to monitor your system’s charge, current, voltage (including open-circuit voltage), and temperature, so choose a controller with an easy-to-read display.
Our Top Picks
When shopping for a solar charge controller, keep an eye out for the amperage rating, durable construction, warranty, type (PWM or MPPT), added benefits like digital display screens, and if the company offers resources to guide you with installation.
Sól Buck Boost 20 Amp MPPT
DIY Solar For U is a small, mom-and-pop business that delivers high-quality products with features not found in other solar charge controllers. Case in point: the global MPPT tracking in the Sol Buck Boost 20 Amp MPPT controller. This added feature finds the global MPPT operating point and then ignores the false maximum that is often triggered by partially-shaded panels, resulting in overall gains in the charge current. While some solar-powered systems struggle in cloudy weather, Sól still manages to extract power from low-light conditions, utilizing all available energy.
For maximum efficiency, it can both lower (buck) and raise (boost) solar voltage to battery voltage, increasing daily total energy input by 29 percent. This unique buck-boost technology allows the controller to operate where buck-only converters aren’t able to.
DIY Solar For U uses automotive and/or military-grade materials wherever possible, and this controller is made in the U.S., (with all parts sourced in the U.S.) with a rugged cast aluminum enclosure. It’s shipped in recycled materials and includes a 5-year warranty.
- Type:20amp MPPT
- Dimensions: 5.8 by 3.7 by 1.6 inches
- Weight: 1 pound
- Warranty: 5-year limited
- Made in the USA
- Designed for a service life of 40 years
- Responsive customer service from knowledgeable people
- LCD display
- Small business
Get the Sól Buck Boost 20 Amp MPPT at DIY Solar For U.
WindyNation TrakMax 40 Amp MPPT
If you’re looking for an MPPT controller at a bargain rate, the WindyNation TrakMax40 Amp controller utilizes a software algorithm to maximize the energy production for your solar panels. Compatible with flooded lead acid, sealed lead acid (AGM), gel and lithium 12V or 24V batteries, this charge controller offers adjustable settings for fine-tuning to a specific battery manufacturer’s algorithms.
An LCD display provides all system information such as amps, volts, solar voltage, battery temperature and load control. The TrakMax is made with virgin PC and ABS plastic and features electronic protection against overvoltage, reverse polarity, overcurrent, excessive temperature and short circuits. This fast sweeping controller optimizes the maximum power point in a short time period, allowing for efficiency of up to 99.9 percent.
Other accessories can be added separately like an optional remote monitor that can be mounted up to 20 feet from the controller and can be especially useful if your solar system is located in a difficult place to reach. Or, there’s a wireless communication adapter (Bluetooth) that can sync with a smartphone or tablet by downloading the free app.
Headquartered in California, Windy Nation was founded in 2009 to offer DIY solutions to solar installation. The company manufactures the TrakMax controller in China with parts sourced globally, and it’s shipped using packaging and printing made from recycled materials. If you have any questions about installation or other solar-related questions, WindyNation has several helpful resource guides available online.
- Type:40 amp MPPT
- Dimensions: 9 by 6 by 4 inches
- Weight: 4.4 pounds
- Warranty: 1 year
- North American-based company
- Thorough, well-written product manual
- Fine-tuning to specific battery brand
- Uses recycled packaging materials
- Add-on module required for Wi-Fi and Bluetooth
- Lower input 100v (voltage at open circuit)
- No end-of-life recycling or buyback options
Get the WindyNation TrakMax 40 Amp MPPT at Amazon.
Renogy Voyager 10 Amp PWM
If you have a smaller budget but are looking for a solar controller for a simple off-grid solar system (like a sailboat or powerboat) the Renogy 10A Voyager is a great option with a simple interface that’s easy for beginners to use. However, if you do need guidance on installation, Renogy has a number of resources on the website (but it’s worth noting that the company’s customer service is slow to respond to inquiries).
With a compact size, it can be installed almost anywhere, and to prevent damage from installation mistakes or system faults, the controller includes built-in, self-diagnostics and electronic protections.
Although PWM controllers are not as efficient as MPPT controllers, the Voyager does have a Smart four-stage charging system (bulk, boost, float, and equalization) and temperature compensation. These features can help to increase battery life, and enhance the overall system performance. However, if you have a larger, more complicated system, this 10amp, PWM controller wouldn’t be the best choice.
Like similar Renogy controllers, it also offers protection against reverse polarity, overcharging, short-circuit, and reverse current and can be used on many types of batteries (including lithium). However, the Voyager has the added advantage of being iP67 waterproof rated, so it can be installed outdoors.
Renogy is headquartered in California and manufactures the controllers in China. The company performs life cycle assessments on products to determine the overall environmental impact of production, however, no end-of-product life disposal services are available for consumers.
- Type:10amp PWM (20amp also available)
- Dimensions: 6.08 x 3.83 x 1.4 inches
- Weight:.55 pounds
- Warranty:2 years
- (PWM) controllers are not as efficient as (MPPT) controllers
- Limited to smaller solar energy systems
- No USB ports
Get the Renogy Voyager 10 Amp PWM at Amazon or Renogy.
Check for a used Renogy Voyager on Amazon.
Victron Energy SmartSolar 30 Amp MPPT
Headquartered in the Netherlands. Victron Energy is considered a world leader in power electronics and specializes in manufacturing equipment required for off-grid and stand-alone power systems. Victron has been building solar energy system components for 45 years and offers well-built quality devices using the latest technology.
The SmartSolar 30 Amp MPPT controller maximizes the energy harvested from the sun to quickly recharge a battery, while at the same time maintaining battery health and extending its life. The SmartSolar charge controller can also recharge depleted batteries with voltages as low as zero (as long as the cells aren’t damaged or permanently sulphated).
Victron has by far the most advanced system monitoring with an inbuilt Bluetooth connection offering easy programming and configuration, plus remote firmware updates which add extra features and options. The display-less controller design may not please all users, but the fast, accurate MPPT tracking, high build quality, and V.E. Smart networking options are stand-out features. In addition, the company offers online training courses about MPPT controllers and other information about solar installation (free signup required).
- Size:30amp MPPT
- Dimensions: 7.25 by 5 by 2.5 inches
- Weight: 2.82 pounds
- Warranty: 5 years
- Advanced monitoring app
- Built-in temperature sensor
- Super fast maximum power point tracking
- No display on unit, requires a Smart device or separate display unit
- No load control
- Expensive
Get the Victron Energy SmartSolar 30 Amp MPPT at Amazon.
Check for a refurbished Victron 30 AMP controller on Ebay.
Renogy Rover 60 Amp MPPT
Renogy is a leading manufacturer of solar panels, batteries, accessories and controllers and the 60 AMP Rover MPPT controller is a solid choice for larger off-grid systems. The versatile unit can be used with sealed lead acid batteries, Gel flooded and lithium batteries, and automatically detects 12V/24V/36V/48V DC systems, making it suitable for RVs, commercial vehicles, boats or other systems.
In the event of an error, this MPPT controller has self-diagnosing capabilities in place to safeguard your system. The Renogy 60A Rover is an intelligent negative ground controller. able to assess and protect against a number of potential problems such as battery overcharging (and over-discharging), reverse polarity, short-circuiting, overload, overheating and reverse current.
The device is made in China from a PC and ABS plastic shell and an aluminum alloy chassis with an integrated heat sink. It has an easy-to-use LCD screen display and multiple LED indicators for displaying system operation information, customizable parameters and error codes. Renogy also offers a Smart performance reader (sold separately) that can be used in conjunction with the controller, allowing you to monitor the system’s performance from your phone.
- Type:60amp MPPT
- Dimensions: 11.22 by 8.07 by 4 inches
- Weight: 9.53 pounds
- Warranty:2 years
- Self-diagnostic for safety
- Suitable for any off-grid system
- Video tutorials offer ease of setup
- Compatible with 12V–48V DC input
- Company routinely participates in charitable initiatives
- Customer support is slow to respond
- App to adjust parameters can glitch
- Misreads battery voltage at times.
- Not waterproof (IP32 rating)
Get the Renogy Rover 60 Amp MPPT at Amazon or Renogy.
Check for a refurbished Renogy Rover on eBay
Our Verdict
The Sól Buck Boost 20 Amp MPPT is the perfect fit for a variety of solar energy system sizes and off-grid applications. It’s in a class all its own with buck-boost technology, top-notch customer service, and its rugged, built-to-last craftsmanship—and unlike most other charge controllers out there, it’s made in the USA. The only downside seems to be the price point, but with a service life expectancy of over 40 years, you should get your money’s worth. If your solar energy system (and budget) is smaller, the waterproof Renogy Voyager 10 Amp PWM is a great place to start and the company is based in the United States with lots of videos and diagrams to make installation easier.
How We Chose the Best Solar Charge Controllers
In determining the best solar charge controllers, we looked at more than 40 solar charge controllers from 20 different companies, factoring in customer reviews, efficiency, durable materials, and warranty repair programs from established brands.
Priority was given to North American-based companies offering accessible customer support and online resources, but we also paid particular attention to the quality of the build for longevity—better for your budget and the environment. We also searched for companies that offered buy-back or recycling programs to ensure a closed-loop production system, but couldn’t find any.
Most of our choices were MPPT controllers because they allow your solar panels to operate at an optimum power output voltage, improving their performance by as much as 30 percent (compared to PWM solar controllers).
FAQs
The following section aims to answer any remaining questions you may have about the best solar charger controllers. Look for the answers to your questions below.
Q: How much do solar charge controllers cost?
Solar charge controllers range from 15 up to 800, depending upon the features, power rating (from 10 amps to 100 amps), and type—with PWM being cheaper than MPPT controllers.
Q: How do I choose the right sized solar charge controller?
In selecting a controller, you must first determine how much power your panels will be producing before evaluating the size of the controller needed. To do this, add up the watts produced by your solar panels (if you have more than one) and divide by the type of voltage your system is using (usually 12, 24, or 48 volts) to get the amperage. However, it is advisable to add a cushion of 25 percent to this number so that you purchase a controller with a slightly higher amperage than estimated. It’s crucial to select the right size controller for your system or it will not function to its full potential. If you need help determining your energy needs, Renogy has a handy solar calculator. and in-depth, step-by-step guidance about sizing a controller for your solar system.
Q: Which is better PWM or MPPT?
Determining what type of solar controller is better depends on the size of your system and your budget. MPPT charge controllers are highly recommended for most large solar power systems. PWM charge controllers are often used in portable applications such as RVs, sailboats, or even conversion vans, as well as smaller immobile structures like a shed, tiny home or an off-grid cottage. However, they’re relatively inexpensive—perfect for upfront savings.
MPPT charge controllers deliver superior performance, with the only real downside being the additional cost compared to more basic options. However, MPPT controllers may provide more savings over the long term, depending on how frequently you use your system.
Q: How do I connect the solar charge controller to the inverter?
You should never plug a power inverter directly into a solar charge controller because they need a battery for reference to control the solar panel’s input. Connecting the controller and inverter directly without a battery can cause severe damage to the components of your solar energy system. To install the controller, you’ll need to connect a battery to the charge controller first and then connect a power inverter to the battery. If you’re a visual learner, this installation video explains how to set up a solar-powered system that uses a controller and an inverter.
Q: What should I do with my old solar controller?
If you no longer have a need for your old solar charge controller, it’s important that it doesn’t end up in a landfill. If it’s still in good working condition, you can offer it for sale on Ebay or a local Yard Sale page. If it cannot be repaired and is no longer functional, some solar manufacturers can assist with the disposal of the units, or you can check with companies that specialize in recycling solar equipment and electronics, such as Zeep Technology.
What Is Solar Charge Controller? Do You Need One?
Depending on the kind of solarstorage system you have, you may or may not need one.
David Kuchta, Ph.D. has 10 years of experience in gardening and has read widely in environmental history and the energy transition. An environmental activist since the 1970s, he is also a historian, author, gardener, and educator.
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A solar charge controller benefits a solarstorage system. The solarstorage system allows customers to use solar off-grid, either full-time or as a backup during power outages. The controller controls the amount of energy being sent into the battery backup so that the battery doesn’t exceed its voltage capacity—thereby extending the life of the battery and avoiding any damage to it.
Depending on the kind of solarstorage system you have, you may or may not need a solar charge controller. In this article, we’ll go through everything you need to know about this tool.
Benefits and Types
The output of a solar panel can vary depending on levels of sunlight, ambient temperature, the quality of the solar cells in the panel, and other factors. All of these factors affect the efficiency of the panels in converting sunlight into electricity.
A solar charge controller smooths out that variability so that batteries receive power at a constant and safe rate. It also sends a “trickle charge” when the battery is nearly full. Since batteries regularly lose a small amount of charge, a trickle charge keeps the battery topped off without overcharging it.
If you have a grid-tied solarstorage system, either ground-mounted or on your roof, you most likely have no need for a solar charge controller. Your excess solar energy will automatically flow into the grid when your battery is full. But if your solar system is operating off-grid, a controller might be a wise investment.
There are two main types of solar charge controllers, Pulse Width Modulated (PWM) and Maximum Power Point Tracking (MPPT). PWM controllers are better suited for small solarstorage systems with low voltage panels and small batteries. MPPT controllers are more expensive, but have more features and advantages; they are recommended for any solar system over 170 watts.
PWM Controllers
The main function of a PWM controller is to protect your battery by making sure solar panels have the same voltage as the battery. The voltage of the battery must match the “nominal voltage” of a solar panel—that is, the voltage the panel is marketed as having, even if the actual voltage can vary and often be slightly higher.
As its name suggests, a PWM controller controls the flow by pulsing the power sent to the battery to slow down or speed up the charging. Some PWM controllers can only handle one voltage level, while others can handle different levels. Either way, the voltage of both battery and panel must still be the same.
PWM controllers are uncomplicated devices, though some can have additional features added to their essentially basic systems.
MPPT Controllers
Unlike PWM systems, where the voltage of battery and panels must be the same, MPPT controllers can charge a lower voltage battery from a higher voltage solar array and, in some cases, a higher voltage battery from a lower voltage solar array.
In electrical systems, voltage and amperage are inversely related: The higher the voltage, the lower the current (amperage), and vice versa. Since an MPPT controller controls the rate and current of the voltage flowing from solar panels to a battery, off-grid solarstorage systems can have panels of different voltage than their batteries.
So while a solar panel by itself with a nominal voltage of 24 volts is insufficient to power a 48-volt battery, an MPPT controller allows it to work by halving the amperage, thereby doubling the voltage flowing into the battery.
Treehugger Tip
For fans of golfing or boondocking (off-grid RV living), an MPPT controller allows you to charge a 36-volt or 48-volt battery with a single flexible 12-volt solar panel attached to the roof of your RV or golf cart.
MPPT controllers can increase the efficiency of your solar panels by 20% to 30% by tracking the optimal voltage-to-current ratio to maximize output to a battery. It’s their increased efficiency that can make their higher cost worth it.
Costs
The simplest PWM controllers can cost as little as 20. Those with additional features can cost up to 200 or more.
MPPT controllers can do more, but cost more, running from 50 to over 1,000, depending on the features. If there is a long distance between your panels and battery, however, you can save money by using lower-gauge electrical wiring between the two, since MPPT controllers modulate current and voltage.
And because MPPT controllers can convert the higher output of a solar array to the lower voltage of a battery, a battery can capture more of the sun’s energy. This will increase its efficiency and potentially shorten the payback time of the more expensive system, as well as increase your ability to rely solely on solar energy.
Some optional controller features that come at additional costs include:
- LEDs to allow users to monitor the voltage and amperage of the system.
- Internet-enabled controllers to allow for remote monitoring.
- Multiple outputs to allow for charging two separate batteries.
- Longer cables for greater distances between panels and battery.
- Temperature sensors, which will maximize the efficiency of charging since batteries charge at different rates during different temperatures.
- Low voltage disconnects, which will automatically disconnect an attached DC-operated device (such as a golf cart) when the battery is low.
As always with solar products, anticipate your solar needs and capabilities, and calculate the costs and payback time to see what kind of system works best for you.