What is a charge controller?

Charge controllers – important battery managers

The charge controller is a device preventing solar batteries from overcharging and over-discharging. One of the most common problems with batteries is that they cannot be discharged excessively or recharged too often. A charge controller controls the charge by managing properly the battery voltage and current.

Charge controllers are intended to protect the battery and to deliver it as longer life as possible while keeping the photovoltaic system efficiency. It should be noted that charge controllers only control DC loads. AC loads are to be controlled (and disconnected, if needed) by an inverter.

The key functions of charge controllers are:

  • Protecting the battery from overcharging by limiting the charging voltage
  • Protecting the battery from deep and/or unwanted discharging. The charge controller automatically disconnects the loads from the battery when the battery voltage falls below a certain depth of discharge value
  • Preventing the reverse current through PV modules at night
  • Providing information about battery state of charge

The main charge controller types available today are PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracking) ones. MPPT charge controllers are more expensive but they can boost the performance of the solar array. PWM charge controllers are less expensive but they can extend the battery bank’s lifecycle at the expense of solar panels performing lower than in case of MPPT controller. Similar to inverters, charge controllers have a lifespan of about 15 years.

A charge controller costs between $500 and $1,000. (However, you can find some low-grade PWM charge controllers for about $30-$50).

This is not a fortune but not choosing the proper charge controller for your system might result in a series of problems. Your solar system might either underperform or not work at all. The worst, however, is that other system components might get damaged.

Therefore selecting a charge controller should not be underestimated.

What kind of charge controller to choose depends on the specific case and is a trade-off between getting more power from solar panels and extending battery life.

To get an idea what controller you need for your system you need neither dig into heavy science nor be a solar guru.

You just have to know some basic info such as:

–      Which type of charge controller is recommended for a given solar system type

–      What maintenance a charge controller needs and how much are its annual maintenance costs

–      When you need a couple of charge controllers rather than a single one

–      Which charge controller type is recommended for hot climates

–      What controller to select for a small solar system

–      What controller you need to connect a 48V-solar array to a 24V-battery bank

You can discover more about charge controllers in our Definitive guide to solar charge controllers.

Click Here to discover more about how the charge controller can boost the performance of your solar system even more.

Click on the following link to use our free pwm charge controller calculator.


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Lacho Pop, MSE, holds a Master's Degree in Electronics and Automatics. He has more than 15 years of experience in the design and implementation of various sophisticated electronic, solar power, and telecommunication systems.  He authored and co-authored several practical solar books in the field of solar power and solar photovoltaics. All the books were well-received by the public. You can discover more about his bestselling solar books on Amazon on his profile page here: Lacho Pop, MSE Profile