216 Cell Microconcentrator Module with Moderate Concentration , ± 4 ° Acceptance Angle , and 13 . 3 mm Focal Length

We report on a demonstration prototype module created to explore the viability of using microscale solar cells combined with microlens array concentrators to create a thin, flat-plate concentrator module with a relatively large acceptance angle for use with coarse two-axis tracking systems designed for flat-plate, one-sun modules. The demonstration module was comprised of an array of 216 cell/microlens units and was manufactured using standard tools common to the integrated circuit, microelectromechanical system (MEMS), and electronics assembly industries. The module demonstrated an acceptance angle of ±4°, an optical concentration level of 36X, and a focal depth of 13.3 mm. The acceptance angle and focal depth of the system successfully demonstrated adequate performance for integration into a system using a coarse two-axis tracker for flatplate modules. To fully take advantage of this system approach, significant future work is required to reduce optical losses, increase cell and module efficiency, reduce the focal length to approximately 5 mm, and increase the concentration level to greater than 100X while maintaining an acceptance angle of at least ±2°. Index Terms — photovoltaic cells, solar energy, silicon solar system.