Solar panels do insulate your roof, but how much cooler your house will be in summer and how much heat loss you can expect in winter nights depends on your home circumstances. Is there external insulation on the roof? Is the space beneath your roof empty attic or living space? Is the space well-ventilated? Is the attic insulated?
At the same time, photovoltaic panels were installed on the roof as a control experiment for the photovoltaic roof. A white insulation material was used on the ground below the panel to eliminate the interference of heat transfer from nearby black roofs on the experimental results.
In the absence of photovoltaic (PV) panels, the heat absorbed by a cool roof (characterized by high reflectivity) is reduced by 65.6% compared to a conventional roof (with low reflectivity). However, once PV panels are installed, the disparity in heat gain between roofs with varying reflectivity levels is narrowed to approximately 10%.
Rooftop photovoltaic panels can serve as external shading devices on buildings, effectively reducing indoor heat gain caused by sunlight. This paper uses a numerical model to analyze rooftop photovoltaic panels' thermal conduction, convection, and radiation in hot summer areas as shading devices.
Therefore, in the hot summer of Wuhan, cool roofs are more energy-saving than traditional roofs, but when photovoltaic panels are installed, traditional roofs are more energy-saving and have more obvious benefits. PV rooftop installation reduces indoor heat gain and achieves cooling benefits through shading.
In contrast, cool roofs have a lower heat absorption rate, allowing them to reflect a portion of the solar radiation and reduce heat absorption, thereby lowering the roof temperature. The painted area was 4 m 2 (2 m × 2 m). At the same time, photovoltaic panels were installed on the roof as a control experiment for the photovoltaic roof.