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Solar charge controllers

If you’re looking to spend time off-grid in your campervan, a solar charge controller is a key piece of kit, harnessing the power from your solar panels.

How does a solar panel charge controller work?

A solar charge controller harnesses the energy from your solar panels and converts it into usable energy to charge your batteries. The voltage of the solar panels can fluctuate massively depending on the intensity of the sun. Therefore, a solar charge controller is required to regulate the voltage from the solar panels and effectively charge your batteries whilst preventing overcharging. There are two types of solar charge controller available: MPPT and PWM.

Climbingvan Victron solar charge controller illustration

MPPT vs PWM charge controllers

PWM solar charge controllers

PWM solar charge controllers act like a switch between a solar panel and a leisure battery, drawing power from the solar panels at just above the battery voltage.

They are a low cost option, and are usually used in more basic systems where the solar panels are being used to trickle charge the leisure battery. An example of this is when solar panels are being used as a backup charging source to shore power.

MPPT solar charge controllers

MPPT solar charge controllers are more sophisticated than their PWM counterparts, drawing power from the solar panels at the ‘maximum power voltage’ (when the power output is greatest).

MPPT charge controllers are therefore more efficient than PWM charge controllers, which means they charge your batteries faster. Consequently, this is why MPPT solar charge controllers are more commonly used.

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Victron solar charge controllers

Victron solar charge controllers have two numbers to help you decide on the correct charge controller for your system. The first number refers to the ‘maximum PV open circuit voltage’. The second number refers to the maximum charging current.

You should also double check the maximum input current on the datasheet. The charge controllers also have a maximum wattage they can be used with. Use our calculator below to help you select the right solar panel charge controller for your system.

Finally, MPPT charge controllers need to be sized correctly according to the total wattage of your solar panels.