Photovoltaic (PV) cells are low-voltage devices that must be connected in series to provide suitable voltage for given applications. PV cells generate a photocurrent when exposed to light, but behave like a conventional diode when shaded. Hence, when one or more cells in a string are shaded, they are reverse biased by the remaining operating cells, which heats and potentially damages them. Array protection is especially critical in space where the higher sunlight intensity results in 40% more available power. To protect against damage, PV arrays often incorporate discrete diodes to bypass these cells in case of shading. These diodes require additional installation steps that increase solar array cost and affect reliability. Our flexible, monolithically-integrated thin-film CIGS photovoltaics are survivable in space and exhibit high specific power. Also, monolithically-integrated CIGS arrays are inherently low-cost due to lower material and installation cost. However, to exploit the above advantages, we must also incorporate monolithically-integrated diode protection. In this program, we shall demonstrate a method to incorporate flexible CIGS diode protection, and thus assuring a simple, low-cost, lightweight protected array for space as well as provide a basis for polycrystalline thin-film devices for flexible electrical components and flat panel displays. Anticipated Benefits and
Potential Commercial Applications: A robust, flexible solar arrays protected by low-cost diodes will have significant impact on both terrestrial and space applications within the consumer, commercial, and government marketplace. In addition to space applications, we are presently manufacturing portable power systems for the military to operate communication equipment, and electronic components such as flexible circuits and flat panel displays.
