AgriEngineering (Oct 2022)
Evaluating the Performance of Flexible, Semi-Transparent Large-Area Organic Photovoltaic Arrays Deployed on a Greenhouse
Abstract
Agricultural greenhouses have been identified as a niche application for organic photovoltaic (OPV) integration, leveraging key performance characteristics of OPV technology, including semi-transparency, light weight, and mechanical flexibility. For optimal electrical design and performance assessment of greenhouse-integrated OPV systems, knowledge of the solar irradiance incident on OPV module surfaces is essential. Many greenhouse designs feature roof curvature. For flexible OPV modules deployed on curved greenhouse roofs, this results in a non-homogenous distribution of solar radiation across the module surfaces, which affects electrical output. Conventional modeling methods for estimating solar irradiance on a PV surface assume planarity, and therefore they are insufficient to evaluate OPV (and other flexible PV) installations on curved greenhouse structures. In this study, practical methods to estimate incident solar irradiance on curved surfaces were developed and then applied in an outdoor performance evaluation of large-area, roll-to-roll printed OPV arrays (3.4 m2 active area) installed on a gothic-arch greenhouse roof in Tucson, Arizona between October–February. The outdoor performance of six OPV arrays was assessed using the curved-surface modeling tools primarily considering the effect of irradiance on electrical behavior. The OPV arrays had an overall power conversion efficiency (PCE) of 1.82%, with lower PCE in the afternoon periods compared to morning and midday periods. The OPV arrays experienced an average 32.6% loss in normalized PCE over the course of the measurement period. Based on these results, we conclude that the higher performing OPV devices that are more robust in outdoor conditions coupled with accurate performance monitoring strategies are needed to prove the case for agrivoltaic OPV greenhouses.
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