High-transparency clear window-based agrivoltaics

Abstract

A number of modern glass and window products based on novel glazing designs, low-emissivity thin-film coatings, and proprietary fluorescent interlayer types have been developed recently. Advanced windows of today can control properties such as thermal emissivity, heat gain, colour, and transparency. In novel glass products, solar energy harvesting through PV integration is also featured, enabled by either patterned-semiconductor thin-film energy conversion surfaces, or by using luminescent concentrator-type approaches to achieve higher transparency. Typically, semitransparent and also highly-transparent PV windows are purpose-designed, for applications in construction industry and agrivoltaics (greenhousing), to include special types of luminescent materials, diffractive microstructures, and customized glazing systems and electric circuitry. Recently, significant progress has been demonstrated in building integrated high-transparency solar windows (featuring visible light transmission of up to 70%, with electric power output Pmax ∼ 30−33 Wp/m2, e.g. ClearVue PV Solar Windows); these are expected to add momentum towards the development of smart cities and advanced agrivoltaics in greenhouse installations. At present (in 2023), these ClearVue window designs are the only type of visually-clear and deployment-ready construction materials capable of providing significant energy savings in buildings, simultaneously with a significant amount of renewable energy generation. The objective of this study is to place the recent industrialised development of ClearVue® PV window systems into a broader context of prior studies in the field of luminescent concentrators, as well as to provide some details on the measured performance characteristics of several ClearVue window design types deployed within the building envelope of a research greenhouse, and to elucidate the corresponding differences in their energy harvesting behaviour. An evaluation of the practical applications potential of these recently developed transparent agrivoltaic construction materials is provided, focussing on the measured renewable energy generation figures and the seasonal trends observed during a long-term study. This article reports on the measured performance characteristics of research greenhouse-based agrivoltaic installation constructed at Murdoch University (Perth, Australia) in early 2021.The solar greenhouse at Murdoch University has demonstrated great potential for commercial food production with significant energy savings due to on-site energy production from its building envelope.