Work

Rooftop boundary layer temperature effects of conventional and cool roof integrated photovoltaic systems

Year: 2026

Type: article

Abstract: Rooftop photovoltaic (PV) deployment is expanding for urban decarbonization, yet the local climatic impacts of standard photovoltaic roofs (PVR) versus cool-roof-integrated systems (PVCR) in arid environments remain unresolved. This study presents a vertically-resolved observational analysis (30–200 cm) of both configurations on the typical Chinese arid urban rooftop (Lanzhou). Both systems achieved substantial daytime roof-surface cooling (PVR: 12.1 ± 1.2 °C; PVCR: 10.3 ± 1.5 °C), but their near-surface air temperature effects were highly stratified. While shading dominated roof cooling, substrate albedo played a decisive secondary role. Notably, PVCR produced warmer roof surfaces and adjacent air than PVR, as reflected shortwave radiation from the cool roof was partially re-absorbed by overlying bifacial panels—a “secondary heating” effect that increased panel thermal load and sensible heat flux. A distinct “thermal dipole” emerged: a shading-driven cooling layer at 30 cm and a sensible-heat-driven warming layer at 60 cm. At 150–200 cm, the signal attenuated; PVR maintained slight cooling, whereas PVCR induced minor daytime warming. Panel-to-air heating efficiency exhibited marked asymmetry between front and back surfaces. These findings demonstrate that rooftop PV restructures near-surface thermal gradients rather than uniformly cooling or warming the environment, suggesting that in high-insolation arid regions, maximizing shading may outweigh albedo enhancement for near-roof thermal regulation. The results are specific to bifacial modules and summer conditions.

Source: Solar Energy

DOI: 10.1016/j.solener.2026.115032

Authors: Dongyu Jia, Liwei Yang, Xiaoqing Gao

Institutions: Lanzhou City University, Chinese Academy of Sciences, Northwest Institute of Eco-Environment and Resources

Language: English

Topic: Urban Heat Island Mitigation

Subfield: Environmental Engineering

Field: Environmental Science

Domain: Physical Sciences

SDGs: Affordable and clean energy, Climate action, Sustainable cities and communities

Open Access status: hybrid

Estimated APC paid: $3,900