photovoltaic system configuration. This permits generating the required voltage directly from the solar array without intervening power electronics. All solar cell strings are identical. Current generated by the solar cells are carried by conductors or by the solar cells themselves. It is noted that no conductors are needed for bringing in the current from the edges of the array, the solar cell strings being arranged in loops which start from one center bus loop around the edge of the array, and return to the other bus at the center of the array. The strings of solar cells start at the centerline of the satellite and go to the outer edge and then back to the centerline. A string, therefore, must cross the primary structural beams, between bays, eight times. Interbay jumper mode of aluminum cable are used to electrically connect strings in one bay to the appropriate strings in the next bay of the string length. Figures B-5 and B-6 show sketches of the reference array blanket support method and the interbay jumper installation, respectively. The solar array primary structure is a truss-type design using 20 m triangular beams as the basic structural element. The structural material is graphite composite. The truss design load results from uniaxial tension of the solar blankets. The truss struts were sized by long column buckling and local crippling. Lightly loaded struts were sized by minimum gauge material. E. Power Distribution The prime function of the power distribution system is to accumulate and control prime power from the silicon solar cell collector panels; control, condition, and regulate the quantity and quality of the electrical power generated for the microwave generators; provide for the required energy storage during solar energy occultation or system maintenance shut-down; and provide for monitoring fault detection, and fault isolation disconnects. Figure B-7 shows a schematic diagram of the solar array power distribution system. The solar array is divided into 228 power sectors. Each power sector is switchable and can be isolated from the main power bus, facilitating solar cell annealing operations and/or other servicing.
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