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A Guide to Solar Charge Controllers: Understanding the Basics


A Guide to Solar Charge Controllers: Understanding the Basics

With the increase in electricity prices, solar systems have become more popular than ever. For the first-time buyer, choosing the right solar system can be difficult. Most people know what solar panels are, and how to size them, but very few know about solar charge controllers, and which one to choose. That said, I’ll talk about everything a buyer needs to know before making a choice.

What Are Solar Charge Controllers

 Solar Charge Controller

Solar charge controllers are used in solar systems to control the charging of the battery or the inverter if a battery isn’t present. It regulates the charging and discharging conditions of the battery. In other words, they control the output of the solar panels and the battery based on the electrical demand of the load, which is the main control part of the whole PV supply system.

Solar Charge Controller Basics

Solar charge controllers perform 2 basic, yet important tasks – preventing the electricity from the batteries from going through the panels when the sun isn’t out, and optimising the charging of the batteries. There are many different types of solar controllers available nowadays, and they’re all separated into two categories – solar regulator MPPT and PWM. Different controllers have different capabilities, which can include the ability to turn DC-powered loads on and off automatically, connect to data networks or provide information about the voltage and amp hours.

How to Size Charge Controllers?

Charge controllers are rated by amperage and voltage. The right solar controller should be able to support the voltage of your array, and the output to the voltage of the battery. You’ll also need to make sure that the controller is capable of handling the current from the solar array. To do that, you’ll need to calculate the panels’ wattage and divide it by the voltage of the battery to get the amperage.

Key Features of Charge Controllers

Charge Controllers

Charge controllers supply the battery with multistage charging, meaning they change the amount of power set to the batteries based on the battery’s level, resulting in healthier batteries. Moreover, controllers prevent the panels from draining when there’s no sun. They also turn off the attached load when the battery is low, and then turn it back on when it’s charged up.

As aforementioned, there are different types of charge controllers available, including 30A and 40A models that safely control the source of energy and protect the batteries from overcharging. On top of this, they provide crucial protection from reverse connections.

Types of Battery Controllers

Charge controllers are separated into two basic types – solar regulator MPPT and PWM controllers.

MPPT Charge Controllers

MPPT Charge Controllers

Also known as Maximum Power Point Tracking controllers, MPPT controllers are the latest type of controllers available today. They’re capable of determining the optimum amperage and voltage of the array, and matching it with the battery. As a result, you get up to 30% more power out of your solar system.

PWM Charge Controllers

Also known as Pulse Width Modulated controllers, these controllers are the most commonly used type, simply because they’re more affordable. These controllers feature a passive technology that takes advantage of solid state gates and switches to provide a constant DC output from a varying DC input.

Why Get MPPT Solar Charge Controllers

MPPT Charge Controller

When you look at all the different solar panels available today, you’ll notice that their voltage range from low to high will vary in normal working parameters. Typically, panels are made to work in excess of 18V, whereas batteries are made to a range of predetermined voltage that’s based on the structure of the battery, a lot of which are 12V.

see the workings of standard PV regulators. It should track the battery state and provides security from overcharging and undercharging. You can connect the regulator right to the battery and then to the solar module. High-quality MPPT charge controllers analyse and adjust the voltage at which the module would generate the most power. The effectiveness of most MPPT charge controllers is anywhere between 93% and 96%. Moreover, MPPT charge controllers provide value in colder weather and on cloudy days when there’s little to no sunshine.

MPPT charge controllers work well together with grid-tied solar modules. They save time in cabling and wiring expenses by utilising smaller gauge wiring and cabling.

So, when choosing an MPPT solar charge controller, make sure it comes with voltage and current regulation, PWM control, temperature compensation, automatic load reconnection and load disconnection and current compensation.

4 Key Factors to Consider


The solar charge controller should be functional and come with all the necessary features for smooth and seamless operation.


The quality of the solar charge controller will depend on the materials. Most controllers are made of either ABS, aluminium alloy or a combination of the two.


Check the buttons and terminals. Shake up the unit. If it sounds like something dropped inside, then it’s not properly assembled.

Customer Support

Make sure you buy from a store that offers quality customer support. This is especially important if it’s your first time dealing with a solar charge controller.

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