Are you a novice or an installer, who has been wondering how to choose an appropriate charge controller for your solar work?. Don’t panic anymore, as you have made your way to this blog post which was written to give a guide on choosing the right solar charge controller for your installation.

What is a solar charge controller?

A solar charge controller is an electrical device used in our solar energy installation, to regulate charges. The controller is normally in between the power source ( panels) and the power storage (battery). It does the work of protecting the battery from overcharging and also shunting the system when the storage power falls below 50%, thereby preventing the battery drainage. At the same time helping in preserving the battery life span.

Working principle of the charge controller.

It works by taking records of charging current flowing through a semiconductor acting like a valve and at the same time limiting the charges entering into the system batteries. When the power bank is fully charged, the controller prevents the current from flowing in again. By so doing preventing the batteries from overcharging.

Easy ways of installing the battery in series and parallel connection.

The charge controller has many other important roles it plays in our installation which are as follows;

Overcharge protection:

when the required amount of rated currents entered a solar installation circuit, it causes lots of damage to the system. Sometimes it can lead to the burning of the circuits thereby risking our lives and properties. But with a charge controller, the device opposes excess current from entering the circuit. i.e it regulates the current entering the circuit, making sure excess current that can damage the system does not go in the system. With a well-rated charge controller, our solar installation is free from overheating caused by overcharging.

Low Voltage disconnects:

in this case, when the battery charges in the battery power bank fell below a defined threshold, due to an overload connected to them, the charge controller automatically disconnects some critical loads connected to the system. And when the batteries got charged the controller automatically reconnects the disconnected loads.

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Blocking of reverse current:

The controller blocks a reverse current from the solar panels from going inside the battery especially during the night when the panels are no longer passing charges to the battery. The panels have an electronic diode that makes the current flow in one direction to the system. So when the panels are no longer passing out electric charge to the system, it naturally passes a current to the system which the charge controller blocks from entering the circuit.

Who needs to install solar charge controller.

People who need the charge controllers are those who have a solar network grid that they manage on their own. But sometimes some people use a solar hybrid inverter which was constructed with a charge controller inbuilt on them. If you are using this type of inverter, you don’t need to install another solar charge controller as the inbuilt one will serve you, or less the amperage of your panels exceeds the amperage of the inbuilt one. In such a case, you can buy a higher amperage controller that will suit your solar grids.

Different types of solar charge comptroller.

Solar charge controllers are of two types, the pulse width modulation (PWM) and the maximum power point tracking (MPPT).

The pulse width modulation (PWM) charge controller.

These types of controllers are the most commonly used. Those who have small solar gride normally makes use of it, because it is cheap to afford compare to MPPT.

It regulates the current and voltage entering into the system. When the batteries charge to it limits the controller stops to deliver in current to system. When making use of this type of controller, its voltage and that of your inverter must be the same.

And the average of the controller must be greater than that of your solar panel. Meaning that if you are having a system of 50A and 12V inverter, the controller must be in 12V and the amperage will be like 60A.

How to choose a solar charge controller
PWM solar charge controller

Maximum power point tracking (MPPT) charge controller.

This type of charge controller is an updated one as it works like an automated device in regulating currents. It makes use of the full voltage drawn from the sunlight, to charge batteries. And when delivering a charging current drawn from the sun, it regulates and sent only the amount the system needed to charge them. When the batteries are fully charged, the controller stops to supply charging current to the batteries. They monitor and regulate the output voltage to suit the system, so as not to overcharge or under-charge the batteries.

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Mppt solar charge controller

How to choose Amps of the controller for our solar network.

when it comes to the sizing of the charge controller for our installation, there are some information we need from our systems. First thing is to choose the type of controller you want to make use of, weather is WPM or MPPT. From the information above, one can easily choose the type of controller he/she can install.

The solar panel voltage and power, are the second thing we put into consideration to install the right one. When you might have gotten the power and voltage of your panels. It is just small calculations to get the actual size and rating the system need.

How to choose the best size of pulse width modulation. (PWM) charge controller for your installation.

when using this type of controller for your installation, try and make sure you appropriately assign the right one because any small mistake can result in damaging the controller. This PWM controller has its amperage rating and voltages written on them. So in this system(PWM), the rule is this, The voltage you are feeding into it must be the same as the controller voltages. And the current of your panels or batteries should not exceed the rated current of the controller.

Let’s for an instant, you are having like eight 12voltage, 100 watts panels connected in parallel. And you are to choose the size of the controller to use for it. All you need to do is to calculate the current of the panel and multiply it by 1.25 i.e the recommended factor of safety.

Simple Guides on solar panel installation.

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To calculate the total current of the solar panels when connected and multiply by 1.25. The reason for multiplying it by 1.25 is for safety because the panels charging sometimes exceeds the rated current when exposed to sun rays. So for our controller to be on the safer side, we need to multiply by 1.25. So that the increase in current won’t affect the controller.

5.29×8=42.32Amps which is the solar panel current, then multiple by 1.25. It will give 52.9Amps.

So, as you got the total current to be 52.9Amp, when buying your controller for the work make sure to buy a controller with is higher or equal to 53amps current rating. And as your battery and solar panels were on 12volt the voltage of the controller should also be on 12volt.

Some PWM controllers do have a voltage rating of 12/24V, meaning you can be able to use them on 12V or 24V provided the current of the panels does not exceed its current.

How to choose the best MPPT charge controller for solar installation.

The MPPT charge controller seems to be the best because of its advantages over PWM. It receives input from the sun’s rays and controls it to suit the system it is serving. Meaning the controller accepts a huge amount of charges and regulates them to suit the system.

Let for instance we have a 60Amp of mppt controller, during operation, this charge controller can be able to receive like 100 amp but at the output, it only delivers 40A which it was designed for.

It also does the same for voltage, it can receive a higher voltage and regulates the voltage to the one the system needs.

When choosing the size of the amp to use in installation work, all you need to do is to calculate the voltage and current of batteries as u did to PWM. Sometimes, we do feed the MPPT controller with a higher volt to make the system give out stable output not minding the weather conditions


7 Replies to “How to choose and size a charge controller for your solar system installation.”

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