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© 1995-2012 IEEE. The design, fabrication, and performance of InGaAs and InGaP/GaAs microcells are presented. These cells are integrated with a Si wafer providing a path for insertion in hybrid concentrated photovoltaic modules. Comparisons are made between bonded cells and cells fabricated on their native wafer. The bonded cells showed no evidence of degradation in spite of the integration process that involved significant processing including the removal of the III-V substrate.

Development of novel micro-scale photovoltaics is presented. A new micro-CPV approach is investigated which seamlessly integrates micro-scale multi-junction cells with a multifunctional silicon platform that provides optical micro-concentration, hybrid photovoltaic, and mechanical micro-assembly. The wafer-embedded micro-concentrating elements lead to dramatically reduced CPV module materials and fabrication costs, as well as an ultra-compact optical architecture with sufficient angular tolerance for low-cost tracking, making the micro-CPV module fully compatible with commercial flat panel infrastructures. The PV/CPV hybrid architecture further allows the collection of both direct and diffuse sunlight thus extending the cost-effective geographic and market domains for PV system deployment.

Robocasting, a solid freeform fabrication technique, was used to develop lattices of hydroxyapatite (HA) that show promise as load-bearing scaffolds for bone repair. Additionally, the lattice scaffolds can be shaped into customized implants. A computed tomography (CT) scan of a damaged mandible was utilized to noninvasively design a lattice implant that could fill the damaged region. In a case study, the fit of the custom lattice scaffold was tested in a damaged mandible and “fit like a glove.” Such implants may be able to replace numerous autograft procedures, thereby reducing surgical cost and complications associated with bone harvesting surgery.

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 flat-plate 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°.

A 100X magnification, ±3° field of view micro-concentrating optical array has been developed with better than 90% transmission for a microsystems-enabled photovoltaic (MEPV) prototype module using 250 µm diameter multi-junction “stacked” PV cells.