A solar array maximum power point tracking system for regulating the power output of a solar array associated with a spacecraft. An on-board computer measures the bus voltage and current from the solar array and generates a power calculation of the solar array power output. The on-board computer applies a first reference signal to a remote error amplifier representative of an incremental change in the solar array power. Additionally, the solar array bus voltage is applied to the remote error amplifier such that the remote error amplifier senses the solar array bus voltage and generates an output voltage indicative of the change of the solar array power. The output voltage of the error amplifier is applied to a power processor unit. The output voltage from the remote error amplifier and the bus voltage are applied to a power stage within the power processor unit. The power stage generates an output current that is applied to an arcjet thruster. The output current is also applied to a transconductive circuit that converts the output current to a voltage so as to condition the input voltage to the power stage.