PWM versus MPPT Solar Charge Controllers – Which is Better?

A solar charge controller is one of the most important components of a solar power system. Usually, solar solar controllers come in-built in a solar inverter. However, if someone wants to upgrade their existing home inverter system into a solar power system, they need to buy a separate device known as Retrofit (an upgraded version of a solar charge controller) in addition to the solar panels. Solar charge controllers come in two types – MPPT and PWM.  But before we find out what MPPT and PWM charge controllers do and how they are different from each other, let us find out what solar charge controllers exactly do and why it is important to install them.

Why Do You Need a Solar Charge Controller?

Overcharging can cause damage to the battery. The solar charge controller works like a regulator that prevents overcharging of batteries by regulating the voltage. So once the batteries are sufficiently charged, the solar charge controller stops the charging. 

Similarly, when batteries are run on partial charge for extended periods of time, it reduces the life expectancy of a battery. Deep discharges, too, can kill the batteries very quickly. The solar charge controllers come with a low voltage disconnect (LVD) switching feature that protects the battery from deep discharges. 

Another important function of the solar charge controller is to prevent reverse current. The solar charge controllers ensure a unidirectional flow of current (from the solar panels to the battery array). So when the Sun goes down during the night and the solar panels are at a lower voltage as compared to the battery, the solar controllers prevents charge flow from the battery to the solar panels

Types of Solar Charge Controllers

There are two types of solar charge controllers – pulse-width modulation (PWM) and maximum power point tracking (MPPT).

About PWM controllers

They are relatively simple. They work like a switch between the solar panels and the battery bank. The switch opens and closes rapidly, thereby allowing charge to flow to the battery. And as the battery begins to approach capacity, the PWM controllers slowly start reducing the amount of power that goes into the battery. Also, for the charge to take place it is required that the solar panels and the battery operate at similar voltages. Due to this, the solar panels often have to operate below their maximum power voltage (Vmp) which is an unnecessary waste of power. And therefore, PWM controllers are recommended for small setups that use nominal voltage solar panels. 

About MPPT Controllers

MPPT controllers are much more expensive as compared to PWM controllers. But they are more sophisticated in terms of their operations and are designed to take full advantage of a solar panel’s maximum power output. MPPT controllers can track and adjust the input voltage and current flowing from the solar panels to the battery. MPPT controllers help ensure that the solar panels operate at their optimum voltage so that it generates maximum power possible. Once they receive maximum power from the solar panels, they vary the output voltage at their end to match that of the battery. So let’s say, there’s a scenario where the voltage needs to be stepped down. In this case, the MPPT will increase the current to ensure that the amount of power it received from the solar panels is the same as the power that goes into the battery, thereby ensuring there’s no loss of power.

PWM or MPPT? Make the Right Decision.

MPPT controllers are undoubtedly more efficient as compared to PWM controllers. However, that doesn’t mean one should always opt for MPPT controllers over PWM. The decision needs to be based on several factors such as application, location, budget and more. We, therefore, recommend you to get in touch with an expert who can help you make the right decision based on your requirement. So, if you are looking for a solar charge controller, You can get in touch with one of the solar experts at Luminous India. They will not only help you choose between a PWM and an MPPT controller, but they will also walk you through the wide range of solar charge controllers that Luminous has to offer. 

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James Williams
James is our Lead Content Publisher here at Feeds Portal. He has worked with many top websites over the years, including BuzzFeed.

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