Análise do ganho de calor em um edifício com fachada fotovoltaica de células monocristalinas : um estudo na cidade de João Pessoa

Abstract

BIPV (Building Integrated Photovoltaic/Thermal Systems) systems represent an innovative technology that integrates photovoltaic and thermal panels to buildings, promoting energy efficiency and sustainability. To evaluate this solution, a prototype was installed in a building in João Pessoa, Paraíba, with the addition of a single-crystal silicon photovoltaic module with double glazing, positioned at 90° on the north facade. Experimental tests were carried out in April, June and July 2024, with the objective of evaluating the heat gain in the environment and the generation of energy, taking into account the climate of the region. The thermal analysis was conducted by calculating the heat gain coefficient (SHGC), using the energy balance on the faces of the BIPV. The instruments used for data collection included anemometer (to measure wind speed), radiometer (for radiation indices) and thermocouples (to record temperatures). The thermal results indicated that the inclination of the module caused significant impacts on heat gain within the environment. The SHGC varied between 0,18 and 0,49. When analyzing the relationship between irradiance and solar heat gain coefficient (SHGC), it was observed that at times of higher solar incidence, the heat absorbed by the building was more intense. The irradiance varied between 450 W/m2 and 730 W/m 2, showing how solar radiation directly influences heat retention in the construction. The heat maps of the photovoltaic module surface revealed interesting patterns over the months analyzed. In April, temperatures ranged from 31,2°C to 51,4°C, while in June they were between 29,1°C and 52,0°C, and in July, between 28,3°C and 50,4°C. It was noted that in April, temperatures showed a wider variation throughout the day, probably due to the positioning of the sun. Already in June and July, the highest values were concentrated in the afternoon. These data reinforce the impact of solar radiation on the heat distribution in the panel, which can serve as a basis for planning more efficient thermal control strategies. In addition, the photovoltaic module recorded temperatures between 40°C and 52°C, tracking the variation of irradiance throughout the day. The power generated by the system ranged from 12,55 W to 94,64 W, and the efficiency of the module showed an inverse temperature trend, recording 24% efficiency for temperatures below 45°C and 22% for higher temperatures. The average energy generated for simulation and experimental ranged from 0,24 to 0,25 kWh/day in April, from 0,28 to 0,24 kWh/day in June and from 0,28 to 0,24 kWh/day in July. The relationship between module temperature and electrical efficiency confirms the importance of thermal control to maximize energy production. The study demonstrated that the efficiency of the integrated photovoltaic module is directly influenced by temperature and irradiance, with thermal losses reducing its performance in hot climates. The analysis of SHGC, heat maps and power generation reinforce the need for cooling strategies to optimize BIPV systems in tropical regions.