PWM Charge Controllers

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PWM Charge Controllers

Charge controller is an essential part of a solar panel system with a battery. It protects your energy storage and prolongs its lifespan. PWM charge controllers are the simplest type of regulators on the market.

Why do you need a charge controller

Every charge controller should be able to

  • protect the battery from high voltage of panels. By connecting a battery to panels without a controller in between, you risk overheating the battery which eventually leads to its early death.
  • prevent the overcharging of a battery and its usage in the state of deep discharge, like a smart battery charger.
  • block reverse currents: at night energy can flow from a battery back to PV modules. Not only are you losing energy, it can potentially start a fire on a roof.

The charge controller also helps you to monitor your solar panel system. It measures the charge of a battery, shows its current state and tells you the voltage of panels. More advanced models offer additional features, like programming the charging process and measuring the temperature outside.

How a PWM charge controller works

PWM charge controllers are actually really simple. They bring the voltage that comes from panels down to the voltage of a battery. This is why you should always use PWM charge controllers only in situations where the voltage of your panels is slightly higher than the one of a battery — otherwise your panels lose too much power. For example, a PWM charge controller fits a system with 30-cell panels and 12 volt battery. To prevent the overcharging, a PWM regulator limits the energy that it receives and makes a trickle of electric charge for a battery. The PWM controller is a good choice with a small residential solar panel system when you don’t aim to get as much energy as possible. 

The simplicity of a PWM charge controllers make them very long lasting — their lifespan oftentimes exceeds 15 years. The warranties for them are usually issued for 2-5 years. Unlike MPPT regulators, they are also very cheap. You can get a PWM controller for $20—$100, so you can easily replace one if it malfunctions for some reason. 

The downside of PWM controllers is their low efficiency. They make use only of 70-80% of electric power that flows through them. Besides, they are suitable only for a small range of systems, whereas MPPT controllers are much more flexible. Even in systems where you can use either a PWM or an MPPT controller, an MPPT regulator is 20-25% more efficient.

How to size a PWM charge controller

A PWM controller goes well with

  • 30-cell panels and 12V battery
  • 60-cell panels and 24V battery
  • 120-cell panels and 48V battery

As it is with MPPT controllers, PWM controllers have maximum amps and maximum voltage: 

  • To figure out the electric current that is going to flow through your future controller, divide the power of your solar array by the voltage of a battery. Amps of your controller should be bigger than that number.
  • To calculate the voltage, add together VOCs (open circuit voltage) of every panel in the array. On cold days voltage can go even higher. To take it into account, add 5 volts on top of every panel’s VOC. The maximum voltage of a controller should be bigger than this sum.

Our store has a variety of charge controllers for sale

  • We have distribution centers on both east and west coasts of the USA: California, Washington, Colorado, Texas, Florida, New Jersey, and Missouri.
  • We guarantee the authenticity of all the products we sell.
  • We process all orders within 24 hours and ship them within 48 hours.
  • Delivery normally takes between 4-7 business days.
  • All of our suppliers are trusted, top solar panel manufacturers.

We have a wide selection of solar charge controllers in stock. Call us, and our A1 SolarStore experts will answer all of your inquiries, help you choose the right product, and complete your order.

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