The author also reviews the evolution of solar-based spacecraft power systems; introduces modes of operations: discharge (boost), shunt, and charge; and covers pulse-width-modulated (PWM) boost power converter for both DC and AC conditions. A configuration tree for shunt mode operation is conceived. Based on the configuration tree, the best topologies, sequential PWM shunt and ripple-regulated free-running shunt, are intensively examined and formulated. Transistor Circuits For Spacecraft Power System provides important information for understanding the relationship between earthbound semiconductor circuits and space borne vehicles.