Abstract: A system, method, and apparatus for a solar cell based sun sensor are disclosed. The system involves at least three solar panel elements and at least one processor. Each of the solar panel elements measures solar power, and generates currents according to the amount of solar power that the solar power element measures. At least one processor utilizes the currents to determine the three-dimensional sun vector. The solar cell based sun sensor system automatically adjusts for effects of any solar panel element degradation by computing a new maximum current reference value for each solar power measurement. The solar cell based sun sensor system is employed by a spacecraft and/or a terrestrial system. The solar cell based sun sensor system is utilized for guidance, for navigation, for tracking the sun's motion relative to a given reference, to keep instruments pointed to the sun, and/or to keep instruments isolated from the sun.