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A to Z of Solar Charge Controllers

Solar Charge Controller

Solar charge controllers may not be the first thing that comes to your mind when you think of going solar. But they are one of the most critical components of a solar power system as they ensure that a solar power system runs efficiently and safely for the years to come. 

Since the amount of power generated depends on various factors such as the amount of sunlight received by the panels, temperature, and a battery’s state of charge, the solar charge controllers play an important role in ensuring that the batteries are supplied with a steady and optimum level of power. So, if you are planning to go solar or are just curious about what solar charge controllers do and how they work, this post tells you all that you should know about solar charge controllers.

Why do you need a Solar Charge Controller?

Here are some of the most important functions of a solar charge controller.

  1. To avoid damage to the solar panel by preventing reverse current flow from the battery to the solar panel. 
  2. Prevent excess flow of current to the battery and thereby prevent the battery from getting overheated.
  3. Prevents battery drainage by shutting down the system when the stored power falls below 50 percent capacity. This in turn helps preserve the life and health of the batteries.

What are the different types of Solar Charge Controllers?

Solar Charge Controllers can be categorized into two main types based on their technology.

  • PWM - Pulse Width Modulation Charge Controllers
  • MPPT - Maximum Power Point Tracking Charge Controllers

About PWM Charge Controllers 

A PWM charge controller is a relatively older technology and also more cost-efficient as compared to the MPPT technology. It is ideal for small applications. And while you may be told that it is less efficient as compared to MPPT, the fact is that it may still be the best-suited for your kind of requirement. (We will talk about choosing between PWM and MPPT in the later part of this article). 

Working of a PWM Controller

A PWM controller is like a switch that regulates the flow of current from the solar panels to the battery. Its job is to ensure that the voltage of the solar panels matches that of the solar battery. Usually, the voltage of solar panels is higher than that of the solar batteries. So, initially the PWM controller brings down the voltage of the solar panel to match that of the battery. Later as the battery starts getting charged, the voltage of the battery rises and the controller allows the solar panels to discharge power at a higher voltage. Finally, when the batteries are fully charged, PWM controllers continue to supply a tiny amount of power to keep the batteries fully charged. 

Note - When the PWM controller pulls down a solar panel’s voltage from its maximum operating voltage (Vmp) to that of the battery there’s a significant loss of power. It is because of this reason that MPPT is not considered a very efficient technology.

About MPPT Charge Controllers 

MPPT charge controllers are more expensive as compared to PWM controllers, and are therefore best suited for larger applications where the solar panels produce large amounts of additional energy. The only downside of an MPPT charge controller is that it has a shorter lifespan because of more components.

Working of a MPPT Controller

One of the reasons why MPPT is termed as a more efficient technology is because it lets the solar panels work at their optimum voltage. It is a smarter technology that continuously tracks solar panel voltage, compares it to the battery’s voltage and then figures out the best power that a solar panel can produce to charge the battery. The MPPT controller then varies the panel voltage accordingly to ensure that there is minimal power wastage and maximum current gets transferred to the battery. In other words, whenever there’s a need to step down the output voltage to the battery, the solar charge controller steps up the current in order to ensure maximum power output. 

PWM and MPPT - Which is better?

MPPT controllers are undoubtedly more efficient as compared to PWM charge controllers. But as we mentioned earlier, which of the two is better-suited for you would completely depend completely on your requirement. 

So let’s say if you have a small setup where the solar panels are not generating too much additional power then it’s okay to install a PWM controller as efficiency is not a very critical concern. Also, if you have a tight budget and would like to go with a more economical option then a PWM controller would best suit your requirement.

Similarly, those with larger setups where there are several solar panels producing a lot of power, it is critical to use an MPPT controller to minimize power wastage. MPPT controllers are also the best option for areas with cold and cloudy climates. 

Planning to switch to a solar power system?

Investing in a solar power system is a one time investment. And therefore, it is important to choose a trustworthy name that has been around for a substantial time. We, therefore, recommend you to go for a reputable solar product brand such as Luminous India. They are one of the most trusted names to reckon with. Also, if you have any doubts or would like to know more about solar power systems, you can get in touch with one of their solar experts and they would be happy to help.

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