Unlike battery inverters, most solar charge controllers can be used with a range of different battery voltages. For example, most smaller 10A to 60A charge controllers can be used to charge either a 12V or 24V battery, while most larger capacity or higher input voltage charge controllers are designed to be used on 24V or 48V battery systems.
The maximum solar array size which can be connected to the solar charge controller is generally limited by the battery voltage. As highlighted in the following diagram, using a higher 24V battery enables more solar power to be connected to a solar charge controller with a maximum charge rating of 20A.
Based on Ohm’s law and the power equation, higher battery voltages enable more solar panels to be connected. This is due to the simple formula – Power = Voltage x Current (P=V*I). For example 20A x 12.5V = 250W, while 20A x 25V = 500W. So using a 20A controller on a higher 24V volt battery, as opposed to a 12V battery, will allow double the size solar array to be connected.
20A MPPT with a 12V battery = 260W max Solar recommended
MPPT 20A with a 24V battery = 520W max Solar recommended
20A MPPT with a 48V battery = 1040W max Solar recommended