How Does a Solar Charge Controller Work?

In this PowerVersity guide, Victor answers the question, “how does a solar charge controller work?”

The guide starts by explaining what a solar charge controller means. It then discusses the types, and what you need to know about the operation of a solar charge controller.

Read through to find all hidden secrets you need to know about a solar charge controller.

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How Does a Solar Charge Controller Work?: What is a Solar Charge Controller?


A solar charge controller is a device – specially designed to regulates the voltage and current coming from the solar panels into the battery.

Solar energy, in its general function, is a basic concept. Attach a solar panel to the DC load, and it will operate until the sun goes down.

Connect solar panel to a grid-linked inverter, as long as the sun is shining, energy will be sent to the utility. It is as easy as that.

Moreover, when power storage is to be introduced, it gets complicated. Especially when the sun is not shining or when the grid is down.

Therefore, there is a need to install battery/batteries are required to store electricity to do useful work later. Hence, the charging controller/ regulator becomes one of the most critical components of the device once a battery is added.

A solar charging controller would be required for someone who goes off-grid or wants to use a hybrid device. Such a person can decide to sell solar-generated energy during the day and store the power for use at night, during an outage, or during peak hours.

How Does a Solar Charge Controller Work?: What It Does

5 Best Solar Charge Controllers

In this section, I will let you see how the charge controller does its work. Before then let me remind you that a charge controller is a regulator.

Let us see how a solar charge controller works.

It Safeguards the Batteries

The charge controller supplies power from the PV array to system loads and the battery bank.

When the battery bank is nearly full, the regulator will cut off the charging current. Thus retaining the necessary voltage to completely charge the battery and keep it topped off.

Batteries are the most expensive part of a solar system. A solar charge controller safeguards them from both overcharging and undercharging.

By being able to monitor the voltage, it safeguards the battery from being damaged. The keyword is “safeguards.”

It Protects Batteries from Over-Discharging

Using batteries in a “limited state-of-charge” will shorten their life immensely. For a lead-acid battery, prolonging periods with a partial state of charge can cause the plates to become sulfated and significantly shorten life expectancy.

Though, lithium battery chemistries are similarly prone to chronic undercharging. In reality, running batteries down to zero can destroy them quickly.

The low power disconnect (LVD) switching bundled with a charge controller prevents batteries from over-discharging.

It Tracks Battery Temperature.

Most solar charge controllers come with a temperature sensor. It is designed to track the temperature and adjust battery charging to maximize the charging accordingly.

For these reasons and more, the solar charge controller can be classified as the brain and heart of the solar system.

It guarantees long-term battery health in all sorts of operating conditions as well as provides critical load control and system monitoring functions,

How Does a Solar Charge Controller Work?: Types of Solar Charge Controller

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

Pulse-Width Modulation (PWM)

PWM solar charge controllers are the most popular kind of solar charge controllers on the market. They are less expensive than MPPT controllers.

When the battery reaches a charge stage, PWM controllers gradually reduce the amount of power going into it. It then ensures a steady supply of a small amount of electricity to hold the battery charged.

Your solar panels and batteries must have similar voltages while using a PWM controller. Panel and battery voltage are not quite the same in larger solar panel systems intended to fuel your entire house.

Based on this, PWM controllers are well suitable for compact DIY solar systems containing a few low-voltage panels and a small battery.

Maximum Power Point Tracking (MPPT)

Solar charge controllers with MPPT are a more expensive and complicated choice. They offer the same switch-like control as a PWM controller, and as your battery bank approaches range, they can limit the power flowing to it.

MPPT charge controllers, unlike PWM controllers, can pair non-matching panels and battery voltages. MPPT controllers adjust their output power to balance the connected battery.

Besides, MPPT controllers change their input to pull in the maximum power available from your solar array.

MPPT charge controllers are more powerful than PWM charge controllers – allowing you to use the maximum power of your solar panels to charge your home battery device.

I hope you found this PowerVersity pick helpful?

If you found it helpful, kindly share your thoughts with the “Leave a Reply” form found towards the end of this page.

Finally, to read more guides like this, visit our Inverters & Charge Controllers page.

Victor Akin-Ojo
Victor Akin-Ojo is the founder and the Lead Editor of Before he started, Victor worked in the IT industry for close to 15 years. He worked mainly as field Engineer on Installation of VSAT, Wimax Technologies, including but not limited to, Power Maintenance Sector for close to 10 years – Designing an electrical installation for Homes, Private and Government Offices and more.
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