Study on Roof Ventilation and Optimized Layout of Photovoltaics for Semi-Outdoor Main Transformer Rooms in Substations

In the context of global decarbonization goals and increasing urban electricity demand, the green transformation of power industry buildings to enhance the utilization of renewable energy represents a significant contribution to sustainable social development. Rooftop photovoltaic (PV) systems can reduce unnecessary radiative heat gain and generate clean electricity to support this transition; however, they also alter the rooftop wind environment. Deploying rooftop PV systems requires well-planned design strategies to optimize renewable energy production while ensuring adequate natural ventilation, particularly for semi-outdoor main transformer rooms where ventilation and heat dissipation are crucial for safe substation operations. This concept was tested at a 220 kV substation in Guangzhou, China, using Computational Fluid Dynamics (CFD) and PVSYST to assess the impact of different rooftop PV systems on natural ventilation and power generation. The analysis showed that while the horizontal PV system achieved the highest energy output, it also resulted in a wind speed reduction of 13.2% or 11.8%. In contrast, the 10° symmetrical PV system offers the most balanced solution, with only a 0.6% decrease in ventilation performance but at the cost of a 13.87% reduction in PV output. The unilateral pitched PV system results in ventilation losses of less than 4%, and the power generation loss is also kept below 4%. However, this configuration may lead to increased wind loads. This approach can be developed into a practical design tool to further support the integration of PV systems in substation green retrofitting projects.