Best Solar Charge Controllers For Sale And Buying Guides

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Solar Charge Controller Buying Guides

Fed up with replacing batteries every year? Or your batteries are discharging quickly? No need to worry anymore! Introducing solar charge controllers that will enhance your batteries’ life and maximize your solar panel’s power. It will save you from the hassle of replacing batteries and ensures that your batteries will have charge when you need it the most.

But you must understand their basic details in order to fully optimize your power stations. Don’t worry, you won’t need a diploma for it but only a few vital details that will help you buy like a professional. So, without any further ado, let’s start from basics and ends on how to choose the best-suited solar charge controller for your solar power stations.

What Is A Solar Charge Controller?

A solar charge controller is solar equipment that manages the current flow going in and out of the battery(s). In simple words, it is a solar regulator that controls the current and voltage coming into the battery so as to prolong the battery’s life. How so?

Well, the batteries are usually damaged due to overcharging and over-discharging. For that reason, you need a regulator that controls the current flow. The solar charge controller automatically detects the battery’s charge status and allows current as per its requirement.

For example, let’s suppose an empty glass. If you start filling an empty glass, you can fill it with a full burst but you must slow down when it is about to full. Otherwise, some water may drip from the glass due to overflowing.

Likewise, the battery will overcharge in the absence of a solar charge controller. Therefore, it is important to control the battery charge and prevent it from overcharging. That’s where the 3 stages solar charge controller comes in. The 3 stages are the bulk, absorption, and float stage.

  • Bulk stage – Sends current in a full burst when the battery has been depleted
  • Absorption stage – After the battery reaches the regulation voltage, the charge controller will reduce the input voltage to safe levels
  • Float stage – When the battery reaches its maximum voltage, the charge controller will only allow a small amount of current to keep it fully charged.

That’s how the 3-stage charge controllers will prevent battery’s damage and enhance its life.

As a matter of fact, it has become a must-have component for every home, industry, or shop utilizing solar grids’ energy. It is been almost a decade that these tools are enhancing the solar panels’ efficiency. You will even find the best solar charge controller for RV.

But in order to be solar-savvy and get the most from these solar panel charge controllers, you must familiarize yourself with their crucial features. No worries, we will tell you all of it step-by-step.

Solar Charge Controller Must-Know Information

In order to be a privy charge controller buyer, you must consider the load first. If you require one for small buildings, caravans, or RVs, you should go for 12 – 24V solar charge controllers with a maximum of 30A. It comes with DC load terminals and is sufficient to regulate charge for your batteries.

On the other hand, you will need a more advanced and high output lithium solar charge controller if you have a larger load. For that, you will need a 60A solar charge regulator(Or other larger power solar charge controllers) which is specially designed for high loads.

How Does Solar Panel Charge Controller Work?

The solar charge controller works as a charge regulator that only allows current to flow in one direction i.e., into the battery. It is installed in the center between the solar panel and batteries to manage and allow the right amount of current from solar grids to loads and energy banks (batteries).

It has the following key functions:

  • Current flow in one direction
  • Stopping battery overcharge
  • Low voltage disconnect
  • Overload safety

But how do solar charge controllers work to perform these functions? Let’s delve in a little deep and discuss each function separately so that you fully grasp its work concept.

Current Flow In One Direction

According to physics law, electricity flows from high voltage to low. At night time, the solar grids lose voltage due to no photons heating their surface. However, the batteries, as being charged, has a higher voltage. Therefore, the current will flow from the battery to the solar panels. That’s the reason, your batteries discharge at night time when you have no solar charge controller installed.

In the presence of a charge controller, the batteries won’t lose their current because it blocks the reverse flow of current. It uses a transistor (a semi-conductor) that allows the current flow only in one direction with zero cost.

Stopping Battery Overcharge

Overcharging the battery is one of the main reasons a battery loses its service life. When the batteries reach their charge capacity, their voltage gets high. As a result, the water starts breaking into hydrogen and oxygen and you may observe bubbles popping inside the battery.

Consequently, your battery will lose water and the gasses may result in a small explosion. Plus, the high voltage may also do harm to the connected appliances and invertor. Therefore, a solar charge controller is used to prevent overcharging.

It acts as a voltage regulator that senses the voltage and controls the incoming energy flow as per the battery’s requirement. The solar charge controller allows maximum energy when the sun’s heat intensity is low. In the same way, it allows half when the sun is fully heating the solar grids and the voltage is high.

Low Voltage Disconnect

You may have heard that the battery will die no matter what you do. Well, that’s a half-truth. Yes, the battery dies after it completes its service life but is your battery completing its life fully? Surely, no if you aren’t aware of the term “over-discharging”.

The batteries’ life reduces when it is fully discharged. It’s like you constantly heat the water pot even if its water has evaporated away. In order to stop it, a solar charge controller comes with a built-in system that connects and disconnects load as per the battery’s charge status.

It has an automatic system that senses the battery’s voltage. When it reduces, the solar panel charge controller disconnects the load until the voltage recovers to normal.

Overload Safety

The batteries life is greatly dependent on its performing plates. In the case of a high current flowing from the solar grids, the plates may get damaged. Therefore, it is best to buy a solar charge controller which has an overload protection circuit. It doesn’t allow high voltage to go into the battery and regulates it as per the battery requirement.

Moreover, the charge controller for solar panels has a unique working principle depending on its type. There are following two types of solar charge controllers:

  1. MPPT Solar Charge Controllers
  2. PWM Solar Charge Controllers

Let’s discuss each type of charge controller for solar panels along with its working principle.

What Is A MPPT Solar Charge Controller?

The MPPT term stands for Maximum Power Point Trackers. It is a solar charge controller that utilizes the panel’s full potential with 0% loss and maximizes the charging efficiency. Commonly, it is recognized as the best solar charge controller worldwide. But how is it different and why is it more expensive than other types of solar charge controllers.

Basically, it is a DC-to-DC converter but with some voltage regulation circuit. Its basic function is to measure the solar grid Vmp voltage and regulate it according to your battery voltage. As a result, it opens doors for large solar panels to charge even small 12V batteries. For example, a 60 cell 20V solar panel can charge 12V batteries with the help of a solar MPPT charge controller.

Unlike other solar charge controllers, the MPPT charge controller doesn’t waste power. It reduces the panel’s voltage to match the battery’s required voltage but in return produces more current. However, experts suggest that you use it only in the case of higher power stations. Generally, it fits best when there are two or more solar grids or when the Vmp is 8V or more than the battery voltage.

How Do MPPT Solar Charge Controllers Work?

The solar MPPT charge controller working principle is quite simple. In fact, it is just about maintaining the current-to-voltage ratio to our benefit. The solar panel’s output voltage mainly depends on the sun’s heat intensity. As the varying sunlight heat can’t provide you with constant voltage, we install a maximum power point tracker to regulate the voltage.

In simple words, the solar MPPT charge controller analyzes the panel and find a ‘sweet spot’ or in other words, the best voltage-current combination. Using this combination, it produces maximum power for your batteries and loads. Furthermore, it has a circuit that automatically adjusts the voltage continuously no matter what the weather conditions are. It means you fully utilize the sun’s heat when it is maximum and minimum.

How does Solar MPPT Charge Controller Work

Anyone with the basic know-how of batteries is familiar with the fact that the batteries can only be charged when the panels’ voltage is greater than the battery voltage. The steeper the difference, the greater will be the current flow. So, to get this difference, you are left with two options:

  1. Maximizing the panel’s output voltage
  2. Minimizing the battery voltage

Maximizing The Panel’s Output Voltage

The panel’s voltage depends on the weather (irradiance). It emits high voltage on a sunny day and less voltage on a cloudy day. Indeed, we can’t control the weather but the panel’s voltage is controllable.

The solar MPPT charge controller is capable of increasing the panel’s voltage on a cloudy day, just like other controllers. But the speciality of this controller is that it can increase the charge efficiency on a sunny day. It can boost the current at the peak time of the day and charge the battery more efficiently by regulating the current-to-voltage ratio.

Minimizing The Battery Voltage

According to ohm’s law, the current and voltage are inversely proportional to each other. Put simply, if the voltage increases, the current drops and same when reversed. The same is the principle of solar MPPT charge controllers. It provides some resistance in the current’s path and increases the voltage. This phenomenon is called voltage-to-current ratio adjustment also known as Maximum Power Point Tracking.

Note that the battery will charge rapidly when it is drained a lot. A battery discharged 80% will charge faster than the battery discharged 40%. Why? Because the 80% discharged battery will have a lower voltage. It means that the voltage and the current difference will be steeper and thus more charge will flow into it.

What Is PWM Solar Charge Controller?

The PWM term stands for ‘Pulse Width Modulation’. It is a simple type of charge controller that regulates the voltage by simply turning the current flow on and off. The PWM solar charge controller has a direct connection with the solar grids and batteries.

Its basic principle is to lower the voltage when it isn’t required. For instance, when the battery loses its charge, the PWM increases the voltage to the maximum. However, when the battery is about to reach its full capacity, it reduces the voltage to the battery’s requirement to prevent it from overcharging. In order to maintain the battery voltage, it continuously turns the current flow on and off (like hundreds of times per second).

The PWM solar charge controller is a cheaper alternative to MPPT solar controllers. It is widely used for small power stations, usually, when there are one or two solar arrays.

Plus, it does not consider the weather but only the battery voltage. It means that even if the solar arrays are providing more voltage, it will reduce it to a minimum to match it with battery voltage. Therefore, the intelligent PWM solar charge controller is only used for small power stations.

How Do PWM Solar Charge Controllers Work?

The PWM charge controllers work as a batter’s voltage regulator. It simply increases or decreases the voltage as per the battery requirement to prevent overcharging. To help you understand the working principle better, let’s consider a typical solar setup.

PWM Solar Charge Controller Working Principle

Let’s suppose a typical solar setup consists of a solar panel, a PWM solar charge controller, and a battery. Consider that the battery is depleted. The PWM charge controller will receive output from the solar arrays and adjust it according to the battery’s optimum charge voltage.

Generally, in a lead-acid battery, the optimum charge voltage is 14.2V. So, the PWM charge controller will push the battery voltage to 14.2V. As the battery reaches its optimum voltage, the PWM controller will reduce the voltage and change into float mode and remain until the battery depletes again. The float voltage is 13.7V which shows that the battery is full.

But what happens when the battery voltage gets slightly below or above the float voltage? Well, the intelligent PWM solar charge controller circuit will increase the input voltage if it gets below 13.7V. Likewise, the PWM charge controller will decrease the input voltage when it gets above 13.7V. This voltage variation is what we call pulse width modulation.

The On And Off Voltage Regulation Technique

You may wonder why don’t the PWM allow partial current flow instead of turning on and off like 100 times in a second. Let’s take an example of a valve stopping the water flow to make you understand the process better.

Suppose a valve functions to prevent water overflow in the storage. When the water storage is empty, the valve fully opens and allows maximum water flow. However, when the storage is close to full, the valve closes partially. Now, the source is supplying the full amount but the valve is resisting it. In electronics, we call this resistance.

If a PWM solar charge controller allows partial current flow and resists the remaining current, then the heat generates and requires a sink for removal. Moreover, the heat will disturb the current measuring sensors. For that reason, a PWM charge controller adopts the full on and off phenomenon to regulate the voltage.

PWM Signal Graph

The above is the graphical representation of a PWM signal cycle. It shows if the modulation is 25%, it means that the PWM controller allows the current 25% of the time and resists the other 75%. The same goes for other modulations.

What Is The Difference Between A PWM And MPPT Charge Controller?

Generally, two types of charge controllers are used worldwide; PWM and MPPT solar charge controllers. But what’s the main difference between them? Let’s compare their features to know them better.

PWM And MPPT Solar Charge Controller Comparison

PWM Solar Charge Controller                  Vs                MPPT Solar Charge Controller

Uses old technology Uses the latest technology
Available at low prices compared to MPPT charge controllers Costly compared to PWM charge controllers
Prevents battery from overcharging Prevent the battery from overcharging and over-discharging
Regulates voltage according to battery voltage Regulates voltage to give a boost to a low battery
Comparatively less efficient than MPPT 30% more efficient than PWM solar charge controllers
Produces noise due to square waves Free of noise
Wastes solar grids’ energy Utilizes full energy of solar arrays with no waste
The life expectancy of around 15 years

The service life of more than 15 years

When Should I Choose A PWM Charge Controller?

The PWM charge controllers have been around for more than a decade. It uses old technology but is still used widely worldwide. It means it is still useful and can be used. But when can we choose it? That’s the question we will answer for you. So, choose the PWM solar charge controllers when:

  • There are one or two solar panels. In other words, it is best for small power stations
  • Your budget is low
  • The panel’s voltage is just a little above the battery voltage. For instance, an 18V solar array to charge a 12V battery.
  • Regions where the weather is mostly hot
  • Harvesting more energy isn’t necessary

When Should I Choose A MPPT Charge Controller?

The MPPT charge controllers are the latest designs and adopt the latest technology. That’s why People prioritize this solar charge controller mostly if it fits their requirements. But when to know if choosing this is our best choice. Let’s tell you when should you choose an MPPT charge controller:

  • It is your best choice for large power stations. Put simply, when you have two or more solar panels installed.
  • Compared to PWM, the MPPT charge controllers are expensive. So, check if it lies in your budget
  • It serves best in cold regions because it utilizes the full energy of solar panels even for the charged batteries.
  • Prioritize this charge controller when the PV is much higher than the battery voltage.
  • It will be an excellent choice if you want to prevent the batteries from overcharging and over-discharging
  • Install MPPT solar charge controller when harvesting more energy is your need.

How To Select Solar Charge Controller?

The solar charge controller enhances your battery’s life and optimizes the charge efficiency. However, it is crucial to understand how to select a solar charge controller for your power stations. In this section, we will reveal four important parameters to consider before buying a solar charge controller.

1. Type Of Solar Charge Controller

As discussed earlier, there are two charge controllers models available; PWM and MPPT. So, our first step is to choose between the two models available.

As we know, the MPPT charge controller is 30% more efficient than PWM. Moreover, it utilizes solar arrays’ maximum power and is compatible for shady days too. For that reason, we can only suggest you buy an MPPT charge controller.

The PWM isn’t a wise choice because the advantages of MPPT solar charge controller are much more than PWM. Besides low efficiency, the PWM will limit your solar array’s output power. I mean, What’s the point of purchasing a 120W solar panel when you can use 100W at max – it is a total waste of money. So, buy an MPPT model. It will cost you 50% more but it will pay for itself within some years.

How To Choose Best Solar Charge Controller

2. Consider Battery Voltage

The solar charge controllers aren’t just optimizing your panel’s output voltage but also charging your battery. So, it is important to check whether your charge controller accepts the battery’s type and voltage.

Mostly, the MPPT charge controllers come with dual compatibility. It will act as a lead-acid and solar lithium battery charger. Still, it is better to check beforehand.

3. Check Your Battery’s Current Capacity

After checking your battery’s voltage compatibility, it is time you check its current capacity. A battery with high current compatibility will charge faster. Usually, LifePO4 batteries support a high current of up to 100Amps and take 2 to 3 hours to get fully charged. So, go for LifePO4 batteries if you need full-time charge filled batteries.

For LifePO4 batteries, we suggest a specially designed LifePO4 solar charge controller. It can provide current up to 100Amps and charge your batteries within 3 hours.

4. Know Your Charge Controller’s Voltage And Current Capacity

Prior to purchasing, check whether your charge controller can accept your panel’s output voltage. No matter how large output your solar panels provide, your solar charge controller will only accept according to its capacity.

Suppose you have four 200W solar grids (20V and 9.8Amps). Two connected in series and two in parallel, you will have 40V output voltage and 8.8Amps output current. In this case, you must choose a solar charge controller that supports 9 Amps and 40V at minimum.

How To Connect Solar Charge Controller?

Both types of solar charge controllers come in the middle of solar arrays and power banks. However, the connecting method for PWM and MPPT charge controllers is different. Let’s learn how to connect both types of charge controllers with the help of our easy step-by-step guide.

How To Connect PWM Solar Charge Controller

The PWM charge controller has 6 ports; two for solar panel(s), two for batteries, and two for the load. If it is your first time installing a PWM, follow the below steps to avoid any mishaps.

Step 1: Connect the battery (make sure it is your first step)

No matter if you are charging lead-acid batteries or (lithium) lifePo4 batteries with solar panels, the procedure is the same. Be it any batter, it will have two terminals; positive and negative. Connect the positive terminal with the positive and negative with the negative. Make sure you use proper battery charging wires. Usually, it comes with the battery but if it didn’t, buy a pair for it.

Step 2: Connect solar panels

The solar panels will have two wires coming out of them; positive and negative. Make sure you know the signs. Otherwise, you may damage the controller. Connect the positive wire with the positive terminal and the negative wire with the negative terminal of the solar charge controller.

Step 3: Connect a DC load (optional)

Most PWM solar charge controllers come with a DC load terminal. If you want to directly charge your phone or give power to any DC appliance, just plug it into the PWM charger’s DC load terminal.

How To connect PWM Solar Charge Controller

How To Connect MPPT Solar Charge Controller

The MPPT solar charge controller has the most advanced and latest design compared to the PWM. Therefore, it takes a little more than 3 steps to connect. If it is your first time, strictly follow the below step-by-step guide to connect your best MPPT solar charge controller.

Step 1: Find the wiring terminals

The MPPT models are different. Some provide a terminal on the outside and some have a terminal inside the cover. So, if you couldn’t find them outside, open the cover you will find six ports. Two for the batteries, two for the solar arrays, and two for the DC load. Additionally, your MPPT model may have ports for the temperature sensor and the PC connection. If you see extra ports, you may see them marked as ‘TEMP’ and ‘PC’ or ‘RS 485’

Step 2: Connect battery

The battery has two terminals, one for positive and one for negative. Use proper charging wires to connect the battery terminals with the ports of the MPPT solar charge controller. Connect positive with positive and negative with the negative terminal.

Step 3: Connect solar panels

The solar panels will have a positive and negative connection. Connect the positive with the positive and negative with the negative of the MPPT solar charge controller’s solar port. Be double sure about the signs or else you may harm your charge controller.

Step 4: Connect DC load (optional)

Most MPPT charge controllers come with a DC load terminal. If you have a separate DC load like a mobile charger, you can directly connect it. However, it isn’t part of the connection between solar array and batteries. Its absence won’t affect the procedure.

Step 5: Connect temperature sensor and PC (optional)

Usually, the MPPT charge controller has a temperature sensor and PC port for extra control and safety. If your charge controller does not come with their wires, buy extra and enhance your control over solar arrays.

How To Connect MPPT Solar Charge Controller

Can I Use Solar Panel Without Charge Controller?

Yes, you won’t need a solar controller charger if you use trickle panels with small maintenance. However, the trickle panels are only compatible when the solar grids’ output is 1% less than the battery’s capacity.

For instance, if your battery is 12V, 100Ah and the solar grid’s output is 1A at 13.4 volts, then a trickle panel would safely trickle charge your battery. Hence, you can use solar panel without charge controller in this case.

Choose Best Solar Charge Controller Supplier For Your Solar Business

Whether you live beside an open road or are cozied up in the woods, the solar charge controller can benefit your solar power station. Firstly, you are required to do some research and consider all the factors mentioned in the article to buy like a pro.

After winding up your research and choosing a charge controller, you will need a trusted solar charge controller manufacturer. Undoubtedly, the charge controllers will optimize your solar panel’s power but only if it is a high-quality product. In the solar market, Vokek is one of your best choices if you want to find top and best solar charge controller supplier in China.

We have been manufacturing solar charge controllers and pure sine wave power inverters for over15 years and are 100% trusted for providing top-notch quality products. Plus, Vokek’s solar charge controller prices are reasonable enough to support you win more charge controller business opportunities.

So, when buying your best solar charge controller, Vokek’s unrivaled quality is what you need for maximizing your solar panels’ power output.

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