Abstract: Improved solar cell circuit layouts and cell structures that protect solar arrays located on spacecraft disposed in geosynchronous earth orbit from electrostatic discharge. An insulating material, such as RTV adhesive, for example, is used as a barrier that disposed in intercell gaps between solar cells. The use of the insulating material modifies sparking in the gaps caused by electrostatic discharge so that, while the spark still occurs, it has different non-destructive characteristics. The use of the insulating material causes no damage to other solar cell materials, such as a Kapton insulating layer or substrate used to support the solar cells. Furthermore, unique solar cell wiring schemes are provided that limit the voltage between adjacent solar cells to 50 volts or less.

Abstract: A battery charging system that may advantageously be used to directly charge a battery of a spacecraft, for example. The battery charging system permits charging of the battery without the use of power conditioners or dedicated charging arrays. Primary and secondary solar array strings are coupled by way of a shunt regulator circuit to a power bus, such as a power bus of the spacecraft. A shunt regulator circuit is coupled to the secondary solar array string and to the power bus. Charge control relays are coupled between the secondary solar array string and the battery. A computer is coupled to the shunt regulator circuit and to the charge control relays. Current from the secondary solar array string is used to charge the battery when the charge control relays are closed. If the computer determines that the battery is fully charged, the charge control relays are commanded open and current flows to the power bus unless shunted by the shunt regulator circuit.