Simple 3-Steps Guideline on How to Select Solar Charge Controller

Solar charge controller, how to use and “how to select a solar charge controller?” It is a must to know to understand its effectiveness.  A ‘solar charge controller’ is required for any solar electric panel. 

It is useful as the batteries store the electrical power generated by solar panels and is later fed into loads. Besides, it prevents batteries from getting overcharged and also avoids discharging at night through the solar panel system.

Read more: Best Solar Charge Controller and Best Solar Car Battery Charger.


What is a Charge Controller?

A charge controller is a device controlling the charge by properly managing the current and the battery voltage. Charge controllers protect the battery and ensure the Photovoltaic System Efficiency to deliver longer life.


  • Restricts charging voltage and protects the battery from overcharging.
  • The charge controller protects the battery from unwanted or deep discharging; it disconnects automatically the battery loads as the voltage falls below the discharge value.
  • Offers information about the charge of the battery.
  • At night, the PV modules are used to prevent reverse current.

Different Types of Solar Charge Controllers

If you have to know how to select a solar charger controller, know the types. They are in two types ‘Pulse with Modulation (PWM)’ and ‘Maximum Power Point Tracking (MPPT).’

PWM is less expensive than MPPT as it boosts the solar system performance. The solar charge controllers offer a 15 years lifespan.

Choosing a proper charge controller is a must to keep your system functioning properly. You cannot rely on your fortune to get the solar system working perfectly. Ensure the requirement.

Do not underestimate or else it will either under-perform or fail to work. The worst is the system will get damaged. 

Pulse Width Modulated (PWM): This charge controller is of the conventional type. These solar controllers send short controlling panels and are less agile.

PMW is enough for places that have steady, constant and strong solar radiation, besides used in cost-sensitive systems.

Maximum power point tracking (MPPT): The ‘MPPT solar charge controller’ is used in large systems providing high performance. MPPT increases the effectiveness of solar charge, connecting a string of panels.

This is an algorithm found in charge controllers that helps to extract from PV module maximum power available. Thus, they produce maximum power.

How does Solar Charger Controller Work?

Solar charge controllers adjust the flowing energy from the PV array to the DC-coupled system batteries directly effectively and efficiently. Thus, ensures a longer life.


  • Coordinates the charge reaching the from the solar panel. It also prevents reverse current flow and overcharging at night.
  • A transistor is used to thrust the charging circuit. It means when the battery is full, the charging stops automatically. Likewise, as your battery reaches a discharge point as unhealthy, the discharging stops automatically.
  • The utility power usage is minimized with the help of a PV charge controller. It also maximizes the batteries and photovoltaic components of life. Thus, the efficiency and life expectancy of the solar system increases.
  • Sophisticated solar charge controllers ascertain the battery is charged with PWM or MPPT, based on their requirements.
  • Inputting the setting of low voltage cut-off and keeping high pre-set, helps in keeping the batteries efficient and healthy.

How to Select Solar Charge Controller – Step by Step Guides

Planning to install a solar charge controller is best done by considering these factors are described below:

1 Step: Voltage selection

As the first step select a system compatible solar charge controller to offer the desired voltage. The normal configurations are 12, 24, and 48 volts. It means for 24 volts battery wiring, you required 24 volts charge controller.

There are voltage specific controllers such that the voltage cannot be substituted or changed. More sophisticated controllers feature an auto-detect voltage feature, that permits using with varying voltage settings.

2 Step: Current capacity

Selecting a solar charge controller implies considering current capacity. It should be such that it can handle maximum output current than a PV panel generates that is referred to as ‘short circuit current’. 

While selecting a solar charge controller, include the safety factor to suit isolated events. For instance, a PV panel as a short circuit current produces 7.89 amp and it means on a sunny day there is 25% extra.

Which accounts for 9.86amp (7.89 x 1.25). Thus, here a charge controller of 10 amp is enough.

3 Step: Look for these features

  • It should have advanced microprocessor control to detect voltage automatically and act by adjusting in real-time the internal workings.
  • It should feature a buck regulator to be used in harnessing systems of solar power.
  • It should protect the system even if there is a fault due to reversed polarity in the system.
  • Safeguard battery from overcharging and prematurely discharging.

What is the Charge Controller size I need?

How to select a solar charge controller, mainly is focused on choosing the appropriate size. Choosing a solar charge controller large in size to work is a must so that it produces the required power and current at any point in time.

The charge controllers is dealt with depending on its size. The rate and size of the charge controllers depend on the amps received and the voltage liberated from the solar system.

Thus, the sizing of a solar charge controller is involved in getting a big charge controller so that the power and current generated by the solar system are sufficient enough. The PV charge controllers are in multiples of 12, up to 48 volts.

The ratings of amperage can be 1-60amps and the voltage from 6-60 volts ratings. In case the volts and the amps of a solar system are different, it is a must to have a solar charge controller meeting the amps requirement.

Nevertheless, there are factors to consider such as increased sporadic current levels and light reflection. It means an additional 25% must be taken into consideration such that the PV charger controller should have 17.5 amps at least.

Thus, for a 12-volt requirement, a charge controller of 20 amp is required. Having higher controller amps helps, regardless of your solar energy system size increase.

MPPT Charge Controllers

An MPPT charge controller is useful with higher solar voltage in comparison to the battery bank voltage. ‘MPPT charge controllers’ work realistically even when the voltage ratings are unusual and are commendable.

The importance of the ‘MPPT solar charge controller’ is in its working. As it observes a voltage difference, it will efficiently and automatically transform the voltage so that your battery bank, panels, and the PV charge controller are equal in voltage.

In case, there is a 900-watt solar panel system with 48 volts, while the voltage of a battery bank is 24 volts, it means you may calculate the required amps that are required by your PV charge controller.

The calculation of the amps is simple. You have to divide the watts by the two volts lower one.

As we know: Watts/Volts = Amps

Taking this above mentioned, it is 900w/24V = 37.5 Amps

Having the required amps implies add 25% for any unanticipated increase of current due to any reason such as light reflection, and so on. Thus, it means 46.87 amps.

This indicates, there is a need for a 50Amps MPPR solar charge controller to get a 24Volt. Concentrating on the sizing is a must to buy a solar charge controller.

How to Size MPPT Solar Charge Controller?

The technological advancements have introduced various ‘MPPT solar charge controllers. However, to concentrate on the size of MPPT charge controllers is a must and it is based on 2 aspects: 

The voltage

Paying attention to the short-circuit voltage and the working voltage is a must. The normal working voltages are 18V, 36V, and so on. In case, it is 18V as the working voltage, the solar panel short-circuits voltage should be 22V.

Likewise, for 36V, there should be a short-circuit voltage as 42V. Thus, choosing the right controller based on the solar panels working voltage is a must. Usually, as you buy the required solar panels, you get all the corresponding parameters.

The current

The solar controller size determines current handling. Generally, the availability is 10A to 30A sizes. Some controllers featuring more power can handle current up to 50A and 60A.

It is not uncommon to have solar controllers of 80A and 100 A. Selecting the controller should be done noting the solar panel discharge current that does not exceed the value.

Thus, choose a controller such that if the current of a solar panel is 6A, choose the 10A charge controller.

The MPPT solar controller’s input voltage is 0~150V, while the PWM is 0~55V. The MPPT controller that is within these values is easily available.

However, in case the input voltages required are higher, you must specify and get it from a solar charge controller manufacturer.

Some Common and Crucial FAQs

Q: What is the solar charge controllers’ function? 

A: A solar charge controller in a battery is an essential component. The key role of a solar charge controller is to manage the charging of a battery bank, prevent it from charging in excess and to control the charging current rate and voltage.

Q: Hints to buy a solar charge controller?

A: PV charge controllers are based on the size and current(amps) requirement as it is based on the push that the solar systems voltage offers. Thus, a solar charge controller involves sizing as the main factor.

A big charge controller handles the current and power generated by the solar energy system. 

Q: Difference between PWM and MPPT?

A: PWM is a switch connecting to the battery the solar energy and has no mechanical connections. The MPPT controllers are the best to convert the surplus voltage into amperage.

It is more sophisticated to harvest power and to transform the acquired power to supply as per the battery voltage requirement plus load balance.

Q: Is it possible with a solar panel to overcharge a battery?

A: Yes, hooking directly a solar panel to a completely charged battery, may result in overcharging.

Q: Does a battery drain due to solar panels?

A: In case the solar panel and the battery are at the same voltage and are started, it will not charge. For instance, a 12V solar panel charging a 12V battery is possible.

But charging using a 12V solar panel, a 24V battery bank means you are stashing 100% potential of the panel, and this may result in the battery draining.


Proper usage of energy is a must and solar charge controllers work round the clock with more speed, functionality, durability, and accuracy.  

There is a need for an effective solar charge controller and so ensure to make extensive research to understand how to select a solar charge controller

Also, do not compromise on the quality based on the cost, if you want your batteries to work for a longer time effectively.