Bradley Howell Jared

Micro-optics for high-efficiency optical performance and simplified tracking for concentrated photovoltaics (CPV)

Micro-optical 5mm lenses in 50mm sub-arrays illuminate arrays of photovoltaic cells with 49X concentration. Fine tracking over ±10° FOV in sub-array allows coarse tracking by meter-sized solar panels. Plastic prototype demonstrated for 400nm

Cost analysis of flat-plate concentrators employing microscale photovoltaic cells for high energy per unit area applications

Microsystems Enabled Photovoltaics (MEPV) is a relatively new field that uses microsystems tools and manufacturing techniques familiar to the semiconductor industry to produce microscale photovoltaic cells. The miniaturization of these PV cells creates new possibilities in system designs that can be used to reduce costs, enhance functionality, improve reliability, or some combination of all three. In this article, we introduce analytical tools and techniques to estimate the costs associated with a hybrid concentrating photovoltaic system that uses multi-junction microscale photovoltaic cells and miniaturized concentrating optics for harnessing direct sunlight, and an active c-Si substrate for collecting diffuse sunlight. The overall model comprises components representing costs and profit margin associated with the PV cells, concentrating optics, balance of systems, installation, and operation. This article concludes with an analysis of the component costs with particular emphasis on the microscale PV cell costs and the associated tradeoffs between cost and performance for the hybrid CPV design.

Cost analysis for flat-plate concentrators employing microscale photovoltaic cells

Microsystems Enabled Photovoltaics (MEPV) is a relatively new field that uses microsystems tools and manufacturing techniques familiar to the semiconductor industry to produce microscale photovoltaic cells. The miniaturization of these PV cells creates new possibilities in system designs that may be able to achieve the US Department of Energy (DOE) price target of

Decentralized nonimaging micro-optical concentrator

1/Wp by 2020 for utility-scale electricity generation. In this article, we introduce analytical tools and techniques to estimate the costs associated with a concentrating photovoltaic system that uses microscale photovoltaic cells and miniaturized optics. The overall model comprises the component costs associated with the PV cells, concentrating optics, balance of systems, installation, and operation. Estimates include profit margin and are discussed in the context of current and projected prices for non-concentrating and concentrating photovoltaics. Our analysis indicates that cells with a width of between 100 and 300 μm will minimize the module costs of the initial design within the range of concentration ratios considered. To achieve the DOE price target of

Photo-Voltaic System Using Micro-Optics

1/Wp by 2020, module efficiencies over 35% will likely be necessary.

The Use of Elastic Averaging for Fabrication of Micro-Optics in a High Efficiency Photovoltaic System

A novel non-imaging micro-concentrator concept and its development in Sandia National Lab’s microsystems-enabled photovoltaics (MEPV) program are described in this paper. Key notions of the compact 2-element optical concentrator are toroidal lens surfaces that decentralize the focused beam and a reflective cone structure that enhances light collection and illumination onto micro-scale solar cells (e.g., ~100’s microns in diameter). The optical configuration therefore provides a low-intensity, hot-spot-free illumination pattern on the receiver while achieving a concentration-acceptance angle product (CAP) over 1. Designs taking into account practical factors (such as fabrication capabilities, misalignments) achieve a 400X geometric concentration with a ±2.4° (90% of peak) acceptance angle (CAP = 0.84) and a 600X geometric concentration with a ±2° acceptance angle (CAP = 0.85), allowing low cost, mass production using injection molding. Development and experimental evaluation of a baseline prototype module is also described.

Micro-Concentrators for a Microsystems-Enabled Photovoltaic System

A photo-voltaic system is under development that uses large arrays of plastic micro-lenses, each illuminating a tiny PV cell stack. This 100-sun system has ±2.50 field of view. Cell efficiency target is >50% with 40% overall system efficiency.

Micro-concentrator module for Microsystems-Enabled Photovoltaics: Optical performance characterization, modelling and analysis

Elastic averaging is introduced as a methodology for the fabrication and assembly of multi-element, micro-optic arrays. Its performance and use is evaluated in the demonstration of a high efficiency, photovoltaic tracking system.

216 cell microconcentrator module with moderate concentration, ±4° acceptance angle, and 13.3 mm focal length

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.

Design of wearable binoculars with on-demand zoom

Prototype micro-concentrating optical modules developed for Microsystems-Enabled Photovoltaics (MEPV) were characterized, modelled, and analyzed. Laboratory and field tests were performed to evaluate the optical performance of the modules. An optical simulation model was constructed based on measured sub-component and material properties, showing a good agreement with on-sun experimental results. Performance of a fully-packaged module integrating 100X micro-scale solar cells (-250μm in diameter) was characterized and projected based on experimental and simulation results. Characterization results and analyses indicate that the micro-concentrator module developed provide desirable performance while maintaining a compact physical profile. The development of a next generation micro-concentrator module is also described.