Journal of Engineering and Architecture December 2020, Vol. 8, No. 2, pp. 42-49 ISSN: 2334-2986 (Print), 2334-2994 (Online) Copyright © The Author(s). All Rights Reserved. Published by American Research Institute for Policy Development DOI: 10.15640/jea.v8n2a7 URL: https://doi.org/10.15640/jea.v8n2a7 Design and Characterization of a Translucent Solar Module (TSM) for Greenhouse Structures Remington S. Ketchum 1 , Hao-Chih Yuan 2 , Liliana Ruiz-Diaz, 1 Nicholas P. Lyons, 1 Sifang Cui, 1 Michael Frasier, 2 Sasaan A. Showghi, 1 Kyung-Jo Kim, 1 Aletheia Ida 3 , Wei Pan, 2 and Robert A. Norwood 1 Abstract There exist numerous advantages of using building integrated photovoltaic (BIPV) technology, including efficient use of solar energy, control of indoor illumination, and reduced energy use for cooling and heating. Current pioneer BIPV technologies have not been fully deployed due to lack of standardization, low adaptability, and moderate efficiency. Here we present a novel, effective, and reliable translucent solar module (TSM) which uses sparsely populated bifacial silicon (Si) photovoltaic (PV) cells and concentrating spectrum-selective dichroic reflectors to illuminate greenhouses and buildings while capturing near infrared light to enhance output. The TSM can be optimized for different applications by changing the dichroic design, varying the shape of the reflector, and altering the tilt-angle of the framing integration with greenhouse structures. Experimental results from a 410 x 500 mm 2 proof-of-concept TSM show excellent agreement with theoretical values, demonstrating a field-of-view (FOV) collection of ±23° and generating up to ~30% more power than a traditional Si PV panel. Keywords: photovoltaics, translucent solar module, greenhouse structures, dichroic reflectors, bifacial silicon 1. Introduction Photovoltaics (PVs) are becoming more reliable and cost-effective. Installing PV systems to convert sunlight into electricity is not just desirable because of environmental reasons, but as a result of economic drivers (Parida, Iniyan & Goic, 2011; Philipps, 2019). One sector that has great potential is building integrated PV (BIPV), where solar panels are incorporated as integral parts of buildings or greenhouses, displacing building material cost, and generating electricity without adding real estate. However, barriers like lack of standards and the complex dynamic between planners, developers, architects, engineers, and installers have restricted the current expansion of BIPV(Heinstein, Ballif & Perret-Aebi, 2013;Hassanien, Li & Lin, 2016).Additionally, in the case of transmissive BIPV, one has to consider how much sunlight can be portioned for renewable energy generation before the reduced irradiance drastically impacts the visual comfort of building tenants or the yield of the farm produce. The optical spectra that are optimum for human vision and plant growth share some similarities. The rod and cone photoreceptors in the human eye are sensitive only to the spectrum between~400 to 700 nm wavelengths (Brown & Wald, 1964). Plants require exposure to specific spectra of light for effective photosynthesis. The absorption of the photoreceptors in plants varies from species to species, but they mainly absorb blue and red light, as depicted in Fig. 1a (Bisegna, Burattini & Mattoni, 2015). Green light, even though not heavily absorbed, still plays a role by driving photosynthetic activity deeper within the leaves(Sun, Nishio & Vogelmann, 1998) and thus, the International Commission on Illumination (CIE) defines the 400 to 700 nm spectrum as photosynthetically active radiation(PAR) (Tibbits, 1993). The spectrum >700 nm, i.e. infrared (IR) range, does not contribute to photosynthesis nor can it be seen by the human eye. Moreover, excessive transmitted IR from the sun heats up the interior space of buildings and, as a result, can drive up demand for cooling and water irrigation. In the U.S., commercial buildings, heating and cooling account for ~35% of the energy consumption (US EIA, 2016) and as much as ~80% in soilless hydroponic greenhouse farming (Barbosa, Gadelha, Kubik, Proctor, Reichelm, Weissinger, Wohlleb & Halden, 2015). 1 James C. Wyant College of Optical Sciences, University of Arizona, 1630 E. University Blvd., Tucson, AZ, 85721, USA 2 DWP Energy Solutions, LLC, 18110 SE 34th Street Building 4, Suite 480, Vancouver, WA, 98683 3 College of Architecture, Planning and Landscape Architecture, University of Arizona, 1040 N. Olive Rd., Tucson, AZ, 85721, USA