agronomy Article Modeling of Stochastic Temperature and Heat Stress Directly Underneath Agrivoltaic Conditions with Orthosiphon Stamineus Crop Cultivation Noor Fadzlinda Othman 1,2 , Mohammad Effendy Yaacob 2,3,4, * , Ahmad Suhaizi Mat Su 1 , Juju Nakasha Jaafar 1 , Hashim Hizam 4,5 , Mohd Fairuz Shahidan 6 , Ahmad Hakiim Jamaluddin 2 , Guangnan Chen 7 and Adam Jalaludin 8 1 Department of Agriculture Technology, Faculty of Agriculture, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia; fadzlin013@gmail.com (N.F.O.); asuhaizi@upm.edu.my (A.S.M.S.); jujunakasha@upm.edu.my (J.N.J.) 2 Hybrid Agrivoltaic Systems Showcase (HAVs) eDU-PARK, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia; ahmadhakiimjamaluddin@gmail.com 3 Department of Process & Food Engineering, Faculty of Engineering, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia 4 Centre for Advanced Lightning, Power and Energy Research (ALPER), Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia; hhizam@upm.edu.my 5 Department of Electrical & Electronics Engineering, Faculty of Engineering, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia 6 Department of Landscape Architecture, Faculty of Design and Architecture, Universiti Putra Malaysia, Serdang, Selangor 43400, Malaysia; mohdfairuz@upm.edu.my 7 Faculty of Health, Engineering and Sciences, University of Southern Queensland, Toowoomba, QLD 4350, Australia; Guangnan.Chen@usq.edu.au 8 Department of Agriculture and Fisheries, Agri-Science Queensland, Leslie Research Facility, 13 Holberton Street, Toowoomba, QLD 4350, Australia; adam.jalaludin@gmail.com * Correspondence: fendyupm@gmail.com Received: 28 July 2020; Accepted: 9 September 2020; Published: 25 September 2020   Abstract: This paper presents the field measured data of the ambient temperature profile and the heat stress occurrences directly underneath ground-mounted solar photovoltaic (PV) arrays (monocrystalline-based), focusing on different temperature levels. A previous study has shown that a 1 ◦ C increase in PV cell temperature results in a reduction of 0.5% in energy conversion efficiency; thus, the temperature factor is critical, especially to solar farm operators. The transpiration process also plays an important role in the cooling of green plants where, on average, it could dissipate a significant amount of the total solar energy absorbed by the leaves, making it a good natural cooling mechanism. It was found from this work that the PV system’s bottom surface temperature was the main source of dissipated heat, as shown in the thermal images recorded at 5-min intervals at three sampling times. A statistical analysis further showed that the thermal correlation for the transpiration process and heat stress occurrences between the PV system’s bottom surface and plant height will be an important factor for large scale plant cultivation in agrivoltaic farms. Keywords: transpiration; PV heat conversion; plant heat stress; agrivoltaic system; sustainable integration; thermal analysis 1. Introduction Dramatic changes and increasing public interest in solar photovoltaic (PV) landscapes show that the dual beneficial use of land may have better impacts on energy production and future agriculture Agronomy 2020, 10, 1472; doi:10.3390/agronomy10101472 www.mdpi.com/journal/agronomy