Height of photovoltaic panels on the roof of the villa

The gain of the inclined overhead photovoltaic roof at 40◦ reaches the best (234.6 W/m2) and then shows a downward trend.” In summer, they also found that the PV roof's daily energy-saving efficiency is the highest, at 18.8%. As the tilt angle increases, the efficiency of inclined overhead roofs shows a downward trend.

Namely, 0°, 15°, 20°, 25°, 30°, 35°, 40°, 45°. “Due to the difference in solar elevation angle between summer and winter, the daily power generation (Epvr) of parallel overhead photovoltaic roofs is optimal (307.2 W/m2) in summer, and the Epvr decreases with the increase of tilt angle,” they explained.

In summer, they also found that the PV roof's daily energy-saving efficiency is the highest, at 18.8%. As the tilt angle increases, the efficiency of inclined overhead roofs shows a downward trend. In winter, the optimal efficiency is found at an inclination of 40◦, with 25.6%, while the parallel case is the lowest.

Researchers in China have investigated the effect of the overhead height and tilt angle on thermal and energy-saving performance of photovoltaic roof and have found that the comprehensive energy-saving efficiency of parallel overhead photovoltaic roofs are optimal in summer and the worst in winter. The experimental setup

“The root mean square error (RMSE) and mean absolute percentage error (MAPE) of the roof with photovoltaic modules are 0.16–2.35 and 0.90%–9.38%,” the scientists said. “Meanwhile, the RMSE and MAPE of the conventional roofs are 0.42–2.55 and 0.95%–8.89%. It is shown that the model established in this paper is reliable.”

The experimental rig used plywood measuring 1,850 mm × 950 mm × 1,850 mm, with a thickness of 15 mm. Aluminum foil covered the surface of the test rig to reduce heat dissipation from the enclosing structure, and the PV modules had dimensions of 1,580 mm × 808 mm × 35 mm.