A research team from China has investigated whether rooftop PV systems can help mitigate heat stress in dairy barns.

“This research provides quantified evidence to support advisory and decision-making processes for farm managers, agricultural policymakers, and PV integrators,” the researchers said in a statement. “By demonstrating that rooftop photovoltaic systems serve a dual purpose—generating clean electricity and acting as a passive cooling solution that reduces peak indoor temperatures by up to 2.3 C during critical afternoon hours—this work directly informs investment decisions in sustainable infrastructure.”

The scientists developed a numerical simulation and validated it against an operational PV system installed on top of a commercial dairy barn. The model enabled calculation of roof heat flux, which is the rate of heat transfer through the roof into the barn interior.

To assess the impact of PV modules on roof heat flux, the team conducted field measurements at a naturally ventilated dairy barn in Shandong Province, China. The barn measures 32 m in span, 372 m in length, and has an eave height of 4.5 m. It features a south-facing gable roof with a 17.17° pitch and a single-layer profiled steel sheet construction without insulation.

The facility was divided into two zones. One section was left without PV installation, while the other was fitted with 1,152 PV modules with a total capacity of 299.52 kW. The modules were installed parallel to the roof slope, maintaining a 0.10 m ventilated air gap between the panels and the roof surface, and covered 60% of the south-facing roof area. The two zones housed 164 and 316 dairy cows, respectively.

To compare thermal performance between the two sections, the researchers monitored indoor and outdoor dry-bulb temperatures, relative humidity, airflow velocity, and solar radiation from June to September 2023. They also measured inner roof surface temperatures using infrared thermography and applied the temperature-humidity index (THI) to assess heat stress conditions in the cows.

The measured datasets were then used to validate a computational model of the barn developed in SolidWorks. The validation showed mean absolute percentage error (MAPE) values of 4%–6% relative to field measurements. With the model validated, the researchers were able to quantify heat transfer dynamics across the barn envelope.

“Linear mixed model analysis revealed that PV panels significantly reduced roof heat flux during daytime (57.7% influence weight, p < 0.001), with the strongest reduction occurring during peak solar radiation between 11:00 and 13:00,” the researchers said. “This effect was primarily attributed to shading, photovoltaic conversion, and convective cooling within the ventilated air cavity beneath the modules.”

“PV panels significantly lowered indoor temperatures during daytime (8.7% influence weight, p < 0.05), achieving a maximum reduction of approximately 2.3 C during the critical afternoon heat stress period (14:00–16:00),” they added.

Overall, the findings indicate that integrating PV systems into livestock housing can deliver measurable co-benefits by simultaneously generating renewable electricity and improving indoor thermal conditions for animal welfare under heat-stress scenarios.

The research work was presented in “Rooftop photovoltaic systems can mitigate dairy barn heat stress by suppressing roof heat flux: a temporal analysis,” published in Biosystems Engineering. Researchers from China Agricultural University, China’s Key Laboratory of Agricultural Engineering in Structure and Environment of the Ministry of Agriculture and Rural Affairs, Shandong Agricultural University, and Beijing Engineering Research Center on Animal Healthy Environment have participated in the study.

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