We are developing lightweight devices that are capable of solar energy conversion and storage. These integrated power supplies (IPS) incorporate photovoltaic power generation with thin-film lithium ion energy storage. Lithium ion devices with large energy densities and long cycling lifetimes are ideal for this application. The techniques used to fabricate the solar cell and battery component films are compatible and scalable. These devices can be designed to fulfill a wide variety of electrical power requirements and are ideal for use with multi-chip modules (MCM) and micro-electromechanical systems (MEMS) for nanosatellites. They provide both the operating power when illuminated and the “stay alive” power during eclipse. We will discuss the design and characterization of the materials used in these devices. The characterization of the devices under simulated lowearth orbit and AM0 illumination will also be presented.