What Size Charge Controller For 100w Solar Panel?

Have you wondered why a charge controller is so crucial for a solar system installation? Well, that is because it protects the battery bank of a solar energy system from overcharging, which can damage the whole system.

Installing a charge controller is not enough; you must use the right type and size. Choosing the right one can be intimidating. But no worries, I’ll show you how you can calculate the size of the charge controller and finally choose the right one.

In the end, I’ll also tell you about different sizes of charge controllers so you know the device better. So, let’s jump right in.

What Size Charge Controller For 100w Solar Pane?

A charge controller is a vital component of a solar system. While various types and sizes of charge controllers are available, you will have to find the right one for a 100W solar panel. Generally, a 10 amp MPPT charge controller is suitable for 100W solar panels.   

Talking about charge controllers for solar energy systems, you must know which size fits your solar panels. The size of a Charge controller is proportionate to your solar panel’s output. The more output your solar panel provides, the bigger your charge controller’s size is.

Since we are talking about 100W solar panels, we’ll calculate the right size of the charge controller for this solar panel. To determine the size, you will have to divide the solar output by the voltage of your battery. Let’s say we have a 100W solar panel and 12V battery.

In that case, the size of your charge controller should be 100/12= 8.33 amps. So, you should use a 10 amp charge controller for one 100W solar panel. If you have 5 100W solar panels, you will need a 50 amps charge controller. As I’ve mentioned, it will increase with the output.

What Is A Charge Controller, And Why Do You Need One?

A charge controller is a component that regulates voltage and current that comes out of a solar panel. It protects the battery from overcharging. If the voltage or current coming out of your solar panel exceeds the battery capacity, it might damage the battery.

So, a charge controller works as a regulator. 100W solar panels are compatible with 12V batteries. Sometimes a 12V panel can produce 16 to 20 Volts of electricity which is harmful to a battery. Without a charge controller, it will surely damage the battery.

Most batteries only need 14 to 14.5 volts of electricity to charge fully. A constant spike in it will harm your battery and, ultimately, the whole solar energy system. That’s why a charge controller is significant, and you must use one.

What Are The Different Types Of Charge Controllers?

We have already learned how vital a charge controller is for a solar energy system. There are various 4 types of charge controllers based on how they manage electricity flow between the solar panel and battery. They are:

  • Shunt Type Charge Controller: When the battery voltage is low the switch turns on and when the battery voltage is high, the switch turns off.
  • Series Charge Controller: Open circuit solar array when the battery voltage reaches at a point and reconnects when voltage drops.
  • Pulse-Wide Modulation Charge Controller: Works as a switch between the solar panel and the battery.
  • MPPT Charge Controller: Ensures maximum current with minimum loss.

Which Type Of Charge Controller Should I Use With 100-Watt Solar Panel?

You have seen the name of 4 charge controllers in the section. Now you might be wondering which one will work better with 100W solar panels. According to many professional opinions, an MPPT charge controller is the best choice for a 100W solar system.

This charge controller system is more efficient than others. An MPPT charge controller is 30% more efficient in managing charges than others. Besides, the panel and battery voltage don’t need to be matched in this system.

Since a 100W solar panel is not that large, you need a charge controller that appropriately manages it without giving up too much voltage, and An MPPT charge controller perfectly fits the job.

How Do I Install The Right Solar Charge Controller?

I guess you know how to install 100 watt solar panel. Now it’s time to know how you can install a charge controller in your solar system. Here’s how you can install the right charge controller for your solar panel:

  • Firstly, determine which charge controller will be suitable for your solar energy system.
  • Then you have to calculate the right size of charge controller for your system.
  • After figuring out these two factors, you are up to installing the charge controller. It’s pretty simple, just plug the cables coming out of your solar panel. Do not forget to maintain the negative and positive terminals.
  • Finally, you have to connect the charge controller with your battery. Now it’s ready to manage your system.

What Factors Should You Consider Before Choosing A Charge Controller?

Before choosing the charge controller for your solar energy system, you must consider some factors. These factors heavily influence your solar system. So, check them before you put up a charge controller.

The first thing you should consider is how many devices and appliances you will use with your solar power. You can calculate them by adding the amps of the devices one by one. After adding all the amps, see how many amps you need per hour.

Then you have to select which battery you will use, Lead-Acid or Lithium-ion. It’s important because the type of battery will determine its size. So, after choosing the type, you can quickly determine its size. Make sure it meets the requirement.

Finally, you will have to determine how many solar panels you need. It also affects the size of your charge controller. If all your requirement is met with one 100W solar panel, then you will need a particular size of charge controller, but if you need multiple 100W solar panels, the charge controller size will increase too.

How many amps should a 100W solar panel produce?

A 100W solar panel can produce about 6 amps per hour when the sun is at its peak. So, you will get 30 amps-hour each day from a single 100W solar panel. But the output can be as high as 8 amps-hour in an ideal situation, which is very unlikely most time.

That is because solar panels’ output depends on many factors. Where and how you install your solar panel, the number of hours your solar panel is receiving sunlight, the weather condition, etc., directly affect the performance of a solar panel.

How Many 100W Solar Panels Do I Need For A 30 Amp Controller?

At this point, you know that a charge controller’s size depends on the output from solar panels. I’ve also shown you the calculation where you can easily determine the size of a charge controller for a 100W solar panel.

A 100W solar panels need a 10 amp charge controller. So, it’s safe to say that you will need 3 100W solar panels for a 30 amp charge controller. If we divide the output by voltage we’ll get, 3×100= 300/ 12= 25. So, we’ll need 3 100W solar panels.

How Many Watts Can A 20amp Charge Controller Handle?

You will need a 10 amp charge controller for a 100W solar panel. According to that calculation, it might seem a 20 amp charge controller can handle 200W. But in reality, it can handle more wattage than that.

Say you have a 12V battery; multiplying the voltage with the amp will give you the exact result. So, 20 amp X 12 V = 240 Watt. So, a 20 amp charge controller can manage as high as 240 watts. That’s the best you can expect from a 20 amp charge controller.

How Good Is A 10 Amp Charge Controller for 100W Solar Panel?

We have learned about the charge controller, size, and other related stuff. Now it’s time to know more about the 10 amp charge controller. You will need a 10 amp charge controller with one 100W solar panel. But how good is it?

In theory, a 10 amp charge controller can manage a maximum output of 150 watts. So, using it for a 100W and 12V solar panel will be safe. It will effectively protect your battery from overcharging. As a result, you won’t have to worry about your solar system.

But make sure to use a suitable 10 amp solar charge controller. We already know there are 4 types of charge controllers available, and you should use the MPPT one for better performance.

Final Thoughts

I would strongly suggest you calculate your solar output and figure out the charge controller size precisely, as shown in this article. Just buying one can be destructive to your solar system.

I’ve explained everything in plain English, but if you still have difficulty understanding, I would advise you to consult with professionals. They will do everything for you.


Acharya, P. S., Aithal, P. S. . (2020, August 1). A Comparative Study of MPPT and PWM Solar Charge Controllers and their Integrated System. Retrieved from IOPScience:

Schmid, F., Behrendt, F. . (2021, June ). Optimal sizing of Solar Home Systems: Charge controller technology and its influence on system design. Retrieved from Researchgate:

Was this article heplful?

Yes No

Leave a Comment