A charge controller is essential to ensure the solar panel does not over charge the battery as well as prevent current drain. For solar panel/s up to 150W choose the 10Ah controller or above, up to 260wp a 20Ah or above and up to 400wp a 30Ah charge controller.
10Ah and 20Ah (dual battery) PWM (Pulse width modulation)
This is a method of reducing the average power delivered by the solar panel to the battery. Turning the electronic internal switch between supply and load on and off at a fast rate controls the charge getting to the battery.
15Ah MMPT Pro (dual battery), 20Ah and 30Ah (single battery) MPPT Pro Plus (Maximum power point tracking)
This is an electronic DC to DC converter which increases solar yield by up to 20% over a standard charge controller by artificially modifying the voltage from a solar panel system to actively match any battery's requirements. This means that whatever the conditions your panel will deliver maximum power with minimum electrical loss. The MPPT charge controllers come with a free-to-download Bluetooth app to display how the solar system is performing