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Solar Charge Controllers: How to Select the Right One for You?

Solar Charge Controllers

Solar power seems to be the up & coming source of power that will finally take over fossil fuels. With time, the development of solar energy has made it possible to be affordable. Nowadays, you can even incorporate solar power into your homes or offices & get off the electric grid completely. However, it’s not that simple, to regulate the power collected by the solar array, you need a solar charge controller.

So, today, we’ll be discussing all you need to know about Solar Charge Controllers.

An Introduction to Solar Charge Controllers

A solar charge controller is a device that regulates the voltage & the current flowing from the solar panel to the battery & other appliances. They are necessary to prevent the solar panel from overcharging the battery & reducing its operational life. In addition, it prevents the battery from draining itself by sending power to the solar panel, during night-time, due to a reversal in the potential difference.

The basic function of a charge controller is to adjust the voltage across the solar power circuit. That is all it does.

Types of Solar Charge Controllers

For all the time that solar power has been in development, we’ve made many innovations, thus, making it more efficient & effective. This also includes the technology that goes into a solar charge controller. Currently, there are three different types of solar charge controllers that you can get in the market.

1 or 2 Stage Controllers

This is the original technology that was put into charge controllers. It’s a system of relays or shunt transistors used to decrease voltage. It essentially cuts off the connection between the panels & the battery, once the battery’s voltage reaches a certain level.
These types of charge controllers are ancient & aside from some old or cheap solar power systems, you won’t be able to find them elsewhere.

Pulse Width Modulation (PWM) Solar Charge Controllers

These are more advanced & are considered industrial standards presently. These form a direct connection between the solar panel & the battery. They essentially pull down the output voltage of the solar panel, almost near to the voltage of the battery. As the battery is charged, its potential increases & the controller does the same with the output voltage of the solar panel.

There is, however, a major flaw in this system. The fact that the controller regulates the output voltage of the panel (the panel is sending less electricity into the circuit), the rest of the energy in the panels is wasted.

For example, let’s say that your panel’s Operating Voltage is 24V & the current flowing through is 10A, but the controller has set the output voltage as 12V. Then according to the equation,

•Maximum Power Output of Solar Panel – V x A = W (Power). 24V x 10A = 240W.
•Power slowing through the circuit into the battery – 12V x 10A = 120W.

This means, that the other 120W of power is wasted & dissipated.

Maximum Power Point Tracking (MPPT) Charge Controllers

These are top-of-the-line & the most expensive types of solar charge controllers available in the market. Unlike the PWMs, these do not control the output voltage of the panel. They calculate the Vmp (Voltage at Maximum Power) of the panel & collect it. Then, it down-converts it, before sending it to the battery. The incoming voltage in the controller is more than the outgoing voltage & according to the law of conservation of energy, this means, that it will increase the current flowing through the circuit.

This means that MPPT controllers eliminate the energy wastage issue faced by PWM controllers. Thus, allowing you to combine solar panels & batteries with varying voltage differences, without wasting energy.

Benefits of Using a Solar Charge Controller with Your Solar Power System

In a traditional power grid, where the flow of electricity is carefully controlled 24/7, to ensure the safety of the grid and the electrical devices of the users. However, when it comes to solar, you are completely off the grid, you are essentially running your power station & grid.

So, who is there to regulate the flow of electricity in your solar power system? Well, that is exactly what a Solar Charge Controller is responsible for.

Prevents Overcharging

Solar charge controllers essentially disconnect the batteries from the solar array, once the charging process is completed. As solar panels always have a higher electric potential, they can overcharge the battery. This results in shortening the battery’s life & may also damage it.

Eliminates Reverse Flow of Charge

It is a basic principle that electricity moves from higher potential to lower potential. This is the reason that solar panels always have a higher voltage than the batteries they are powering. However, after the sun goes down, this changes, in the lack of sunlight the electric potential of the solar array will essentially drop to zero. This can result in the electric current flowing from the battery to the solar panel.

Solar Charge Controllers prevent this by disconnecting the battery from the panel once the panel’s voltage drops below the potential of the battery.

Switch From Array to Battery Automatically

In addition to disconnecting from the solar array, controllers also disconnect the battery from the load/electrical appliances when the volt gets too low. This prevents the battery from being completely discharged & extends its life.

How to Select the Right Solar Charge Controller for Yourself?

First & foremost, do you even need a charge controller? For panels with output power ranges from 1W – 5W used for trickle charging or storage, you don’t need to use a solar charge controller. In other cases, we advise that you include a charge controller in your solar power system.

Another thing to keep in mind, that’ll help you select between PWM & MPPT controllers, is size. PWM charge controllers are pretty much standard in modern times. This is because they are reliable & less expensive. Although they are less efficient than MPPT, the cost is negligible in case of small to medium size power systems. 

When it comes to bigger systems, you may choose MPPT. It is more expensive & has a shorter lifespan as it includes more components. However, they are nearly 96% efficient, meaning virtually no loss in power. This can save a lot of cost & energy when charging larger batteries.

In conclusion, for small to medium settings like your home, it is best to use a PWM solar charge controller. But for large settings, like industries or big buildings, MPPT is a better choice in the long run.

Disclaimer: The information presented here is for general information purposes only and true to best of our understanding. Users are requested to use any information as per their own understanding and knowledge. Before using any of the information, please refer to our Privacy Policy and Terms and Conditions.

  • Created on Mar 22, 2023
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