Things You Must Know Before You Buy a Solar Charge Controller

A solar charge controller plays a critical role in ensuring that a solar power system runs safely and delivers optimum output. But simply buying a solar charge controller is not enough. One also needs to make sure that they buy the right type of solar charge controller and one with the right configuration. If you, too, are planning to go solar or are looking for a solar charge controller here are a few things about solar charge controllers that will help you make the right buying decision. Let’s take a look.

Why Buy a Solar Charge Controller?

As its name suggests, one of the main functions of a solar charge controller is to control the amount of charge that flows into the battery. The solar charge controller protects the battery from getting overcharged and reverses current flow during the night. Here’s how a charge controller protects these devices.

Protecting the battery from damage due to overcharging

As we know, solar batteries have a limited charge storage capacity. A charge controller’s job is to vary the amount of charge flowing into the battery depending on the voltage of the battery which in turn depends on the amount of charge a battery is holding. As soon as the battery gets fully charged, the controller cuts off the voltage from flowing into the battery.

Protecting solar panels from damage due to reverse current flow

Typically, when two electrical devices are connected, charge flows from a device with a higher voltage to a device with a lower voltage. During the night, solar panels are at a lower voltage as compared to solar batteries, and therefore, there’s a risk that current may flow from the battery to the solar panels. This reverse flow of current can damage the solar panels. To avoid this, a solar charge controller is used that acts as a valve preventing the reverse flow of current from the battery to the solar panels.

Types of Solar Charge Controller – PWM and MPPT

There are two types of solar charge controllers – PWM (or Pulse Width Modulation) and MPPT (Maximum Power Point Tracking). Both types have their own pros and cons. For example, PWM is cheaper as compared to MPPT, however, when it comes to efficiency, MPPT controllers are considered more efficient as compared to PWM controllers.

Choosing Between PWM and MPPT – Factors to Consider

MPPT controllers are undoubtedly more efficient as compared to PWM controllers and some people might even suggest you choose an MPPT controller over a PWM controller. But that’s not right. Your choice of a controller should depend on several factors such as your budget, application, temperature conditions, and more. Here’s a detailed comparison for you to make the right buying decision.

Application (Size of the system)

The size of the solar power system is an important factor when choosing a charge controller. Bigger the requirement/application, the bigger the solar power system. While MPPT controllers are best suited for heavy load or professional applications, PWM controllers are recommended for small-scale applications. In fact, installing an MPPT controller in a small scale or low load application is a waste of resources and money.

Temperature Conditions

MPPT controllers perform better as compared to PWM controllers when operating in colder climates. Usually, MPPT controllers produce 20-25 % more charge than PWM controllers. That’s because when the temperature reduces, the Vmp (maximum power voltage) of an MPPT controller increases. Unlike PWM controllers that are unable to capture this excess voltage, the MPPT controllers not only capture this excess voltage but are also able to charge the batteries faster.


Since MPPT controllers are more efficient and used for large applications, they are relatively more expensive than PWM controllers. However, if someone is sitting on a tight budget and they do not require a controller for a heavy load application, a PWM controller is a good alternative.

Want to buy a Solar Charge Controller?

Whether you are planning to buy a solar charge controller or want to have a new solar power system installed on your property, you should consult a solar expert, first. They will help you select the right solar charge controller based on your actual requirement.

Also, if you are looking for an experienced solar expert with in-depth knowledge about solar power systems, you should get in touch with any of the solar experts at Luminous India. They will not help you choose the right solar charge controller, but will also clear your doubts if any.


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