Non-Mechanically Moving Solar Directing System for Photovoltaic Modules
Navy SBIR FY2013.1

Sol No.: Navy SBIR FY2013.1
Topic No.: N131-019
Topic Title: Non-Mechanically Moving Solar Directing System for Photovoltaic Modules
Proposal No.: N131-019-1018
Firm: Phoebus Optoelectronics LLC
12 Desbrosses Street
New York, New York 10013
Contact: Roman Akmechet
Phone: (917) 703-4647
Abstract: We propose a two-layer anti-reflective coating (ARC) that will have omni-directional properties. This coating will guide the light that is incident from oblique angles and orient it to become perpendicular to the solar cell surface. The top-most part of the coating will have a graded index of refraction, starting from an index of 1 at the air interface and gradually increasing to an index of about 1.5 at the interface between the two coating layers. This top layer will be made out of cheap polymer that can be deposited by dip-coating, and the graded index will be achieved by texturing the polymer to have up-right pyramids. As the light travels through this layer, it will bend to become perpendicular to the surface of constant index regardless of initial angle of incidence. The bottom layer of our proposed coating will consist of a standard silicon nitride (SiN) thin film layer that will act as an interference ARC between the polymer and the silicon surface of the solar cell to minimize reflections between each layer. We believe this approach offers cost and weight advantages over not only current mechanical solar directing systems, but also other similar graded ARCs based on silicon oxide.
Benefits: We believe the proposed omni-directional anti-reflective coating will increase the average yearly efficiency of stationary solar cell modules to be on par with modules that are mounted on mechanical solar trackers. The proposed coating will be cheaper to impalement than current mechanical trackers, and will require no maintenance, which makes it possible to become widely adopted in both commercial and residential solar panels. It was suggested that, unlike other graded index coatings based on silicon oxide and titanium oxide, our proposed graded index polymer coating can be developed to be applied to curved surfaces and curved solar cells, which further increases the benefit of this research effort. Curved solar cells are proposed as a power source for cars, manned airplanes, and UAVs. Such applications are sensitive to weight, and our coating adds very little weight to the solar cells. Finally, the deposition and patterning process can be integrated into a standard production line without heavy capital investment.