The bypass diode assembly: solar cell protection for Space Station Freedom

When a shadow partially obscures a large solar array, the large power dissipated in the reverse direction can degrade the shadowed cell. A bypass diode, a diode connected in reverse polarity to the solar cell, can prevent damage to the solar cell and thus extend the operable life of the solar array. A single bypass diode for the Space Station Freedom (SSF) solar array protects eight cells. The custom diode housing required by the flexible array fits within the thin envelope and increases its mechanical stability and thermal capacity. The SSF solar arrays require the use of bypass diodes with minimal thickness (less than 0.02 mm). During the bypass diode assembly development phase, 11 different configurations were examined which utilized a number of candidate materials. Measurements and analyses were performed to eliminate unsuitable configurations, resulting in the parallel contact ceramic hybrid configuration as the final design selection. This configuration which has been shown to meet all requirements.<>