The Amount of the CFM Air Flow is based on the input voltage and Watts available. Speed 1 is 19 volts of input. Speed 2 is 29.5 volts of input.nSpeed 3 is 34 volts of input. The Solar direct units increase and decrease the airflow based on the voltage and watts the solar panel is generating. The Power kits with battery will give you a consistent output based on the consent Voltage of the battery system.