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!
Find out how much you can save by installing solar
- 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.
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.
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!
All about solar charge controllers
Also called charge controllers, solar charge controllers have been around for decades. They are used in almost all solar energy systems to optimize the charge of batteries from PV panels. Find out everything there is to know about solar charge controllers in this article.
What is a solar charge controller?
The solar charge controller is an electronic device connected between the solar panels and the battery. Its role is to regulate the charging process of the battery and ensure that the battery is properly charged, more importantly, that it is not overcharged.
Solar charge controllers are classified according to the maximum input voltage (V) and the maximum charge current (A). These two values determine the number of solar panels that can be connected to the charge controller.
While this technology has been around for many years, modern solar charge controllers have more advanced features. They ensure that the battery system is charged accurately and efficiently. The controllers also manage various functions such as the DC charge output used for lighting.
Most small charge controllers (12V-24V up to 30A) are designed to charge battery only. They are used for special vehicles, van, sailing boats. For large installation MPPT solar charge controllers above 60A also includes a built-in inverter starting from 3KVA. They are specifically designed for small isolated off-grid power systems.
Read also: Alternator, charger, solar panel. Which solutions to adopt to produce electricity while protecting my battery park?
MPPT and PWM solar charge controllers
There are two types of solar charge controllers, the PWM and the MPPT. The latest are much more efficient especially in cold weather. It allows a much better quality of charge starting from 170W PV.
PWM solar charge controllers
Many solar chargers used simple PWM, or pulse width modulation technology. In this case solar charge controllers operate as a switch between the solar array and the battery. They use a basic quick switch to modulate or control the battery charge. The switch is then opened until the battery reaches the absorption charge voltage. Then the switch begins to open and close rapidly (hundreds of times per second) to modulate the current and maintain a constant battery voltage.
If this system works, the solar panel voltage is pulled down to match the battery voltage because PWM controllers cannot modulate the voltage. This has the effect of moving the panel voltage away from its optimum operating voltage (Vmp). This reduces the power of the panel and, therefore, its efficiency.
PWM solar charge controllers are cost effective option for small 12V systems. They are effective when one or two solar panels are used. That is, for simple applications such as solar lighting, camping and small device uses such as USB phone chargers. Note that if more than one panel is used, they should be connected in parallel, not in series.
MPPT solar charge controllers
MPPTs or maximum power point tracking are much more advanced than PWM controllers. They allow the solar panel to operate at its maximum power point, or more precisely, at the optimal voltage for maximum power output. With this Smart technology, MPPT solar charge controllers can be up to 30% more efficient, depending on the battery voltage and the operating voltage (Vmp) of the solar panel.
As a general rule, MPPT charge controllers should be used
:- On all higher power systems using two or more solar panels
What is an MPPT (Maximum Power Point Tracking)?
An MPPT is an efficient DC-DC converter used to maximize the power output of a PV solar panels or turbines. The first “Power Optimizer” the world’s first Maximum Power Point Tracker was invented in Australia in 1985 by Australian Energy Research Laboratories (AERL), and this technology is now used in virtually all grid-connected solar inverters and many solar charge controllers.
The principle of operation of an MPPT solar charge controller is quite simple: due to the variation in the amount of sunlight (irradiance) on a solar panel throughout the day, the panel voltage and current change continuously. In order to produce more power, the maximum power point tracker scans the PV voltage to find the sweet spot or best combination of voltage and current. The MPPT is designed to continuously track and adjust the voltage to generate the maximum power, regardless of the time of day or weather conditions.
Note: Typically, only high-end MPPT controllers can detect partial shadows or are capable of tracking multiple power points. With this Smart technology, the efficiency of the solar panel increases and the amount of energy generated can be up to 30% higher than a PWM solar charge controller.
Dolphin Charger® products are suitable for a wide application such as backup power systems and solar and wind power. AC/DC battery chargers, DC/DC boosters, DC/AC inverters/chargers, batteries, battery managers, man-machine dialogue interfaces (HMI), as well as many accessories such as automatic Smart relays, dc/dc converters, solar regulators, load balancers. Dolphin Charger designs, manufactures and distributes a complete range of robust and Smart power conversion products and solutions. With our own team of engineers, we operate especially for the OEM and ODM market, with custom and communicating solutions perfectly adapted to your needs. You want to realize a project? Please contact us!
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Solar Charge Controller: 5 Tips to Help You Avoid Oversizing
Estimated Read Time: 10 minutes
TL;DR: Choose the right-sized solar charge controller by considering your system’s energy needs, operating temperature, battery chemistry, and professional advice. Off Grid Direct offers a range of controllers with free shipping, price match guarantees, and a 30-day return policy.
Table of Contents
When it comes to solar charge controllers, bigger isn’t always better.
Unless you’re planning to fit more solar panels into your system, an oversized charge controller will be underutilised and a waste of money.
You’re better off to purchase a smaller and more affordable controller that suits your setup and performs all the necessary functions, including:
- Solar output monitoring to ensure charge effectiveness
- State of charge monitoring to prevent overcharging
- Auto shutdown in case of voltage spikes to protect your devices
- MPPT Technology (Maximum Power Point Tracking)
We’ve gathered five tips to keep you informed and help you avoid oversizing. As we delve into each idea, you’ll also learn:
- Why battery chemistry matters
- Why it’s important to consider your panel’s current output
- How temperature affects a charge controller
- The best place to find the perfect sized charge controller
Determine Your System’s Energy Needs
To determine a system’s energy needs, you need to compare the maximum power output (wattage) of the solar panels relative to the nominal voltage of your batteries.
The division of these values (wattage/nominal voltage) results in a system’s power rating and an effective way of sizing your charge controller.
This equation accurately predicts the energy level your charge controller will have to cope with, thereby guiding your choice in terms of size and preventing a mismatch.
The best-sized device should be equally rated with an additional 25 percent safety factor for unexpected conditions, such as current-raising temperature drops.
Let’s put this into perspective.
Suppose your panels have a maximum output of 300 watts and your battery has a 12V nominal voltage. What is the optimum size for your charge controller?
- The system’s energy rating will be 25 Amps (from a division of 300 watts by 12 volts).
- The best-sized controller will be equal to 25 Amps plus a 25 percent safety factor.
- A 25 percent safety factor of 25 Amps is 6.25A (from the multiplication of 0.25 by 25 Amps).
- As a result, the optimum size for your charge controller will be 31.25 Amps (from a sum of 25 and 6.25 Amps).
Take Into Account the Operating Temperature
As mentioned earlier, temperature can affect a solar panel’s output current, hence the 25 percent safety factor when calculating the energy level a your controller will be handling.
However, a device’s rated operating temperature range is also important.
When conditions exceed this temperature range, a charge controller will suffer in its ability to regulate panel output.
The transistors within the device that acts as switches malfunction from the heat and experience current leakage. This results in improper energy regulation and charging inefficiencies as is the case with an oversized charge controller.
Take the instance of a 50A charge controller regulating a 10A solar panel. The unutilized 40A charging potential means a longer charge time for your battery and an overall inefficient solar setup.
Similarly, when conditions fall below the specified operating temperature, the components within your controller malfunction from the cold.
The transistors lose conductivity and experience delayed on-off switching times. This creates sensor inaccuracies and impacts the voltage regulation ability of your charge controller. As a result, your solar charging system becomes ineffective.
Choose a solar controller with a wide operating temperature range for optimal results. This ensures resilience and enables your solar system to work efficiently in various environments and conditions.
The Victron BlueSolar MPPT Charge Controller, for instance, has an impressive operating temperature of between.30 to 60°C.
This device can therefore withstand the scorching conditions of the Pilbara region of Western Australia, known to hit 50°C in the summer. You can be confident that it’ll put up with any condition you throw at it.
“It rapidly finds the maximum power point and seems to build local profiles to swap back to in rapidly changing conditions, from direct sun to dark rain and in the middle.”. Neil F. reviewing Victron BlueSolar MPPT
Choose the Right Type of Charge Controller
There are two main types of charge controllers: Maximum Power Point Tracking (MPPT) and Pulse-Width Modulation (PWM).
Both prevent overcharging and undercharging, but they have distinct technologies with size implications that must be considered to avoid oversizing.
A PWM controller uses a simple on-off transistor technology to regulate the voltage sent to your batteries. As such, it’s cheaper and highly robust, but better suited for smaller solar setups.
Its simplicity is such that a PWM controller will always limit energy to its rated voltage, regardless of panel output.
So, a 13V PWM controller will limit charge flow to 13 volts even if you connect it to an 18-volt panel output. The extra energy is simply dissipated as heat, making this controller inefficient for larger solar setups.
An MPPT controller, on the other hand, uses a more sophisticated voltage monitoring technology to extract maximum power from your panels. This makes it pricier, but more efficient for larger solar setups.
When connected to a large solar array, an MPPT controller will drop the panel output voltage to match your battery while increasing the charging current in the same ratio.
This adjustment allows it to draw maximum power from all your panels, speeding up charge time and enhancing efficiency.
The following table highlights the major differences between PWM and MPPT charge controllers to help you make the right choice.
|Solar Charge Controller||Application||Price|
|PWM||For smaller systems (under 200W) where efficiency isn’t critical such as trickle chargers||From 50|
|MPPT||Essential for larger systems (over 200W) where the extra energy yield from efficiency is worthwhile such as house panels. Still beneficial in smaller systems||From 150|
Consider Your Battery Chemistry
Batteries have different chemistries and a distinct charging profile with implications for your solar charge controller and its size. Therefore, it’s crucial that you understand your battery and its charging requirements to avoid oversizing.
Lead-acid batteries have a complex multistage charging profile requiring various current levels. These stages include a bulk charge, taking up 70 percent of battery capacity, and the absorption and float charge, using the remaining 30 percent.
This chemistry requires a multistage charge controller with a matching current rating (size) to deliver the right charge at each stage—preferably an MPPT controller because of its current adjusting capability.
Lithium-ion phosphate batteries (LiFePO4) have a simpler charging profile and don’t require voltage adjustments. However, they’re incapable of overcharging and only take what they can absorb.
Therefore, a simple on-off PWM controller of the right voltage will be effective at delivering a constant charge and switching off once your battery is full. However for Maximum charge efficiency a MPPT should be used.
Get Professional Advice
Getting professional advice will help you size your charge controller based on the critical aspects discussed above. It also ensures you pick the best model for your specific system and location.
But the biggest advantage is that a solar expert will help you get the most out of the properly sized components through proper installation.
The DIY videos certainly make it look easy, but proper installation goes beyond standard screws and wrenches. It takes specialised equipment to ensure each component is primed to deliver maximum efficiency. For example:
- A solar pathfinder to assess the shading on your rooftop and determine the best placement for maximum solar exposure
- A multimeter to test the overall efficiency of your system by monitoring current flow from panels to batteries and by showing readings on electrical resistance
- A tiltmeter to test the angle placement of your panels to ensure maximum sun exposure
- An infrared camera to spot temperature differences across your panels before they cause system failure
When it comes to solar charge controllers, it’s easier and faster to consult a professional.
Get the Right-Sized Charge Controller From Off Grid Direct
So there you have it. Five tips to help you avoid oversizing your solar charge controller. With these ideas in mind, here’s why we think you should shop at Off Grid Direct.
We’re passionate about bringing value to the marketplace and excited when the customer (you) gets the best deal for bringing sustainability to their home or business.
- Free shipping for orders above 300
- Price match guarantees if you can find a better offer out there
- 30-day easy returns if you’re not happy with your purchase
Contact us today or check out our solar solutions and take advantage of our incredible offers.
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
- Equipment Quality
- Programming Capabilities
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.
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.
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
Ultimate Guide to MPPT VS. PWM
Both MPPT and PWM charge controllers are frequently employed when using solar energy to recharge batteries. The terms MPPT and PWM may be familiar to you if you’re interested in solar power for the off-grid building, camping, or home power backup.
While managing off-grid PV systems, adequate battery charging is a crucial factor to consider. Hence, it is much more critical than you might realize to include the proper solar charge controller in your system. On this page, you will discover what MPPT and PWM are, MPPT vs. PWM, and how to select the best solar charge controller.
What Are The MPPT and PWM Controller
By controlling the amount and rate of charge to your batteries, the solar charge controller, located between the energy source and storage, avoids overcharging batteries. Additionally, they stop battery drain by turning off the device if the amount of power stored drops below 50% of its maximum level and charge the batteries at the proper voltage. The batteries’ life and health are preserved as a result.
MPPT Solar Charge Controller
Maximum Power Point Tracker controllers are typically more expensive than PWM controllers because they are more efficient and complicated. The electronics enable MPPT controllers to control the solar panel’s Maximum Power Voltage (Vmp). Our Tracer 3210An series has a reported efficiency of 98% thanks to this, which offers 5-25% greater efficiency than the PWM.
Also, using an MPPT charge controller when your PV arrays are more significant is more economical because they often operate at a greater voltage than your batteries. It allows the controller to capture more solar energy by turning all the excess voltage into the current.
PWM Solar Charge Controller
Compared to the MPPT, a PWM charge controller has a simpler charging function. Due to the charging function’s simplification in design, an average PWM charge controller will only have 75–80% efficiency, which means it will not convert all of the solar panel’s higher voltage potential into the current.
Pulse Width Modulation is abbreviated as PWM. PWM charge management devices can be considered electrical switches between batteries, which can be turned on and off rapidly. As a result, the batteries can be charged at the specified voltage. A gradual reduction in charge current will occur as the batteries charge.
MPPT VS. PWM: What Differences
Everyone would use MPPT controllers if maximizing charging capacity were the only consideration when choosing a solar controller. Nonetheless, the two technologies are distinct, and each has unique benefits. Concerning MPPT vs. PWM, the choice is based on the site’s characteristics, the components of the system, the size of the array, and the cost.
MPPT VS. PWM: Appearance
Both MPPT and PWM controllers include electrical connectors for connecting the batteries and solar panels, and they look very similar. Both also have LED lights to check how things are working. The size and weight of MPPT charge controllers are greater. Because they don’t require large DC-DC convertor coils, PWM charge controllers are typically smaller.
MPPT VS. PWM: Working Principle
The technology in the MPPT controller is more advanced and effective. The MPPT charge controller converts high to low-voltage power using a DC-to-DC converter. To always supply the batteries with the maximum power point, it monitors the maximum power point that the solar array can produce and balances voltage and current by the P = V x I equation. The voltage will equal the battery bank, as shown in the image below, but the current will rise.
- The panel’s open circuit (Voc) voltage must be lower than the allowed value.
- For the controller to kick in, the VOC must be higher than the start voltage.
- The maximum panel short circuit current (Isc) has to fall within the predetermined range.
- The maximum array wattage. some controllers let this be oversized, for instance, the Redarc Manager 30 can have up to 520W attached.
The PWM controller acts as an electrical switch to connect the batteries and the solar panel directly. When the battery has to be charged, the switch can open and close at predetermined intervals. When the switch is completed, the PV array’s voltage is forced to match the battery’s voltage. Thus, utilizing a PWM controller will result in a significantly reduced power output. The voltage is concentrated in the diagram below to match the battery voltage, but the current remains unchanged. This is due to the PWM’s need for current adjustment.
- When the charger mode is set to bulk charge, the switch is ON.
- To maintain the battery voltage at the absorption voltage, the switch is flicked ON and OFF as necessary.
- After absorption is complete and the battery voltage reaches the float voltage, the switch is turned off.
- To maintain the battery voltage at the float voltage, the switch is once more flicked ON and OFF as necessary.
MPPT VS. PWM: Temperature
The PV system gets hotter when the sun shines on the solar panel. The open-circuit and maximum power point voltage decrease when a solar-heated panel warms up, but the current stays constant.
An MPPT controller may extract more power from a solar array under colder temperatures than a PWM model can since the operating voltage at maximum power point at Standard Testing Conditions (25C°) is approximately 20V, and the battery voltage is about 13.5V. In chilly temperatures, an MPPT controller can generate up to 20–25% more than a PWM controller.
A PWM controller, in contrast, is unable to change either the voltage or the current because the pulse width modulation technology meets the low battery voltage and the corresponding current in the I-V curve.
MPPT VS. PWM: Costs
PWM charge controllers cost little money. Several inexpensive PWMs are available online for 15–25. However, when purchasing one, caveat emptor is unquestionably in effect. Better ones start at roughly 40 to 50. Yet, the price of the more effective MPPT charge controllers can range from 80 to 500, depending on the voltage and current (A) rating. The cost will play a significant role in your choice.
MPPT VS. PWM: Shading of Panels
The P-V curve has just one maximum power point (MPP) when a solar array runs with evenly distributed solar radiation over its surface. Trees, clouds, or other objects may block some sun rays outdoors. The MPPT controllers can track the several maximum power points that the partial shade produces and set the highest MPP as the operation point. Still, the fundamental operation of a PWM cannot manage this scenario.
MPPT VS. PWM: PV or Battery Voltage
With both varieties of charge controllers, for the battery to charge, the PV voltage must be higher than the battery voltage. Regardless of the PV voltage and battery voltage differences, MPPT charge controllers perform effectively. For instance, with an MPPT, a 36V solar array may effectively charge a 12V battery.
When the solar panel voltage, or incoming PV voltage, is near the battery voltage, PWM charge controllers perform at their best. With multiple PWMs, a 12V solar array and 12V battery provide the optimum configuration. A PWM charge controller will be less effective, with a more significant discrepancy between PV and battery voltage.
MPPT VS. PWM: Series vs Parallel Connections
But series wiring isn’t always the best choice. For instance, parallel wiring is functional when the panels are frequently exposed to various lighting conditions. You can connect more solar panels in series with MPPTs because they nearly invariably have larger PV voltage limits than PWMs. For instance, 100 volts is a typical PV voltage limit for MPPTs. As the open circuit voltage (Voc) of many common 12V 100W solar panels is roughly 22V, you could series-connect up to 4 without exceeding this limit.
You must typically connect many solar panels in parallel when connecting them to a PWM. This is because many PWMs only support one or two 12V solar panels connected in series due to low PV voltage constraints (e.g., 25V or 50V).
MPPT VS. PWM: Pros Cons
The functions of MPPT and PWM charge controllers in a solar power system are identical. For your convenience, we create a list of MPPT vs. PWM pros and cons.
Solar Charge Controller
Maximum Power voltage Tracking up to 99% AIP Conversion rate.
Multi-charging maintains the battery’s health.
Available for purchase in a sizeable off-grid power system.
Available for 100 Amp solar systems.
Provide flexibility when system expansion is necessary.
Costly Pricing (usually cost twice of a PWM Charge Controller).
Larger than a PWM regulator in size.
PWM controller uses sophisticated and tested methods.
PWM controller has a simple structure, and the price is lower.
Smaller-scale deployments are simple.
The battery bank voltage must equal the input voltage.
Less scalability for system growth.
Inability to handle higher voltages.
How to Choose Your Solar Charge Controller
There you have it—a feature-by-feature comparison of MPPT vs. PWM. The PWM charger still has room, but the MPPT charge controller is better than the PWM charge controller.
- MPPT Charge Controller:The best option for business owners looking for a controller that can handle difficult jobs (Home Power Supply, RV Solar Power, Boat, Hybrid Solar Power, and off-grid power station). Due to its powerful capabilities, it can help you save money by reducing other expenses and gaining a lot of power.
- PWM Charge Controller:It works best for small off-grid power applications with lots of money and little need for additional functionality. The PWM controller is the best option if you only need a simple, affordable charge controller for a modest lighting system that doesn’t aim to satisfy the expectations of others.
Why Choose MPPT Over PWM
There are numerous benefits to selecting an MPPT solar charge controller as your perfect PV system component.
- Energy:Depending on the climate, MPPT controllers boost the energy harvest from solar arrays by 5 to 30% compared to PWM controllers by operating array voltages above the battery voltage.
- Fewer Module Restrictions:Because MPPT controllers run arrays at voltages higher than battery voltage, a more comprehensive range of solar modules and array designs can be employed. They can also accommodate systems with smaller wire diameters.
- Solar Arrays:Unlike PWM controllers, MPPT controllers may support bigger arrays that would otherwise go above the charge controller’s maximum operational power restrictions. The controller achieves this by restricting the array’s current consumption when solar energy production is at its highest, often in the middle of the day.
Jackery with Best MPPT Solar Charge Controller
Jackery is a solar generator pioneer and top-selling brand recognized by over 100 authorized organizations worldwide. The Jackery Portable Power Station enables efficient solar charging with a built-in MPPT controller. The multi-stage charging procedure of an MPPT charge controller allows it to transition between charge methods depending on the PV condition automatically. The Jackery solar panels transform sun energy into electrical power, which is then stored in portable power stations for later use. With sizable capacities and high operating leverage, the Explorer series satisfy your massive power use for all purposes that you will encounter.
There are over 12 Jackery portable power stations, which range in dimensions and capacities. The Explorer 2000 Pro. Explorer 1500 Pro. Explorer 1500. Explorer 1000 Pro. and Explorer 1000 deliver enormous charging capacity powering all your required appliances, including TV, blenders, coffee maker, mini cooler, and more. They are equipped with an AC outlet, a DC carport, and USB charging connections so that you can use them for long-term camping trips, off-grid living. and emergency power supplies for your house. The portable power stations are compatible with Jackery solar panels. Also, the stations support pass-through charging, which allows you to charge your power station, with essential devices still plugged in, enabling you to simply and rapidly charge on the go.
Jackery Explorer 2000 Pro
3AC Outlets, 2USB-A Quick Charge 3.0, 2USB-C PD 100W, 1Car Outlet
Light(13W) 100H, TV(60W) 22H, Cooler(21W) 70H, Heating Blanket(40W) 68H, Coffee Maker(1000W) 2.2H, Electric Stove(1150W) 90Min, Mini Cooler(90W) 15H, Electric Grill(1600W) 1.1H
Jackery Explorer 1500 Pro
31800W AC Charging Ports, 2USB-C Charging Ports, 1 Car Charger
Ice Shaver(700W) 1.7H, Mini Fridge(90W) 10.5H, Coffee Maker(1120W) 1.3H, Bluetooth Speaker(10W) 88H, Drone(90W) 35Times, Light(5W) 115H
Jackery Explorer 1000 Pro
2100W PD Ports, 31000W AC Ports, 2USB-A Ports, 2USB-C Ports, 1DC Carport
Light(13W) 60H, Cooler(21W) 34H, Heating Blanket(40W) 35H, Coffee Maker(1000W) 4H, Electric Stove(1150W) 40Min, CPAP(10W) 80Times, Tower Fan(45W) 17H
Meanwhile, the Explorer 500. Explorer 300. Explorer 240 are affordable, lightweight, portable power stations with USB Type-C, USB-A, and an AC outlet, so they can power your iPhone, laptop, and lights while camping or working from home. The Jackery Explorer series has a solid handle for easy carrying. It is simple to use wherever you go due to the push-button operation. The Jackery Explorer series contains a built-in MPPT controller for maximum eco-friendly solar recharging efficiency with the SolarSaga solar panel. You can also recharge the Explorers with a wall outlet, car outlet, and generator.
1AC Outlet (500W, 1000W Peak), 3USB-A Ports, 2DC Ports, and 1Carport
Light(5W) 45H, Phone(iPhone) 53Charges, Laptop(Mac) 4.5Charges, Camera(5W) 54Charges, TV(60W) 5H, Blender(50W) 7H, Mini Cooler(60W) 9H
2AC Outputs, 60W PD USB-C, QC3.0 USB-A, USB Port. 12V carport
Light(5W) 24H, Phone(iPhone) 30Charges, Laptop(Mac) 4Charges, Camera(5W) 54Charges, TV(60W) 4.5H, Drone(60W) 5.5Times, Fan(5W) 15H, Mini Cooler(60W) 4H
1AC Outlet (110V 200W, 400W Peak), 2USB-A Ports, and 1DC Carport
Light(5W) 21H, Phone(iPhone) 24Charges, Laptop(Mac) 3.5Charges, Camera(5W) 11Charges, TV(60W) 3H, Drone(60W) 4Times, Fan(5W) 15H, Electric Blanket(55W) 4H
MPPT VS. PWM FAQs
The following are the frequently asked questions about the MPPT vs PWM:
Why is MPPT better than PWM?
The MPPT controller is more worthwhile to purchase than the PMW controller in terms of quality, additional features, investment-output ratio, and various other variables. Several MPPT controllers have Bluetooth remote controls attached, allowing users to read and adjust the controller from a distance.
For solar charge controller, which one is better?
No matter how they operate PWM or MPPT, the goal is to control the current flowing from the energy source (a solar array) to the battery to avoid the battery from being overcharged. Whether you choose MPPT or PWM, select a charger with a well-known brand, superior quality, and numerous positive reviews. Jackery is a perfect choice!
Is the MPPT controller worth it for a 12v panel system?
For systems using 12-volt panels, an MPPT controller is a wise choice. MPPT offers many advantages, including improved energy transfer efficiency compared to PWM charge controllers. Alternatively, you can select a portable solar generator that combines solar panels with power sources; in terms of conversion efficiency and quality, the Jackery could be the best.
In conclusion, check a solar charge controller’s operations, the conditions, the functions you would require, and your budget before selecting one for yourself. This page compares MPPT vs. PWM to help you decide which type of charge controller you need. Before buying your charge controller, make sure to take the aspects above into account. Also, Jackery helps to build your solar system with the best MPPT charge controllers in its portable power stations.
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