Tilt and Orientation of a Flat Solar Collector to Capture Optimal Solar Irradiation in Chilean Latitudes

Abstract

The use of solar technologies is growing steadily throughout the world since solar radiation is recognized as an inexpensive and local renewable source of energy. At the same time, it helps to reduce the great environmental impact caused by the exploitation of non-renewable energy sources. Accurate information about incident solar radiation over an inclined surface is important for selection and installation of solar technologies. In this study, seasonal and annual total irradiation values received on a flat solar collector were calculated by varying the inclination angle from 0° to 90°, and the azimuth angle from −180° to 180° for 12 cities in Chile, based in one typical meteorological year. The study provides useful information about the influence of the tilt and azimuth angles to the total seasonal and annual solar energy collected. Several cities of Chile located from north to south were selected for the study, including Arica, Calama, Antofagasta, Vallenar, La Serena, Valparaiso, Talca, Concepcion, Los Angeles, Valdivia, Puerto Montt, and Puerto Natales. The isotropic sky model was used to calculate the total irradiances. The results showed that during the summer months the average irradiation values were above 150 kWh/m2 in all cities. During the summer months, the device may be inclined between 0° and 30°, whereas during the winter months it is recommended to reset the inclination angle between 30° and 60°. The estimated annual solar radiation gains, based on tilt and azimuth angles, compared to a horizontal surface, increase toward the south with a maximum gain 10.08% for the city of Puerto Natales. The lowest gain was for the city of Arica with 0.55%, which shows that its best use is close to the horizontal surface. Although, the range of inclination and azimuth angles to achieve optimal irradiation values is wide, it is recommended to set the tilt angle of the flat solar collector between 0° ≤ β ≤ 60° and the azimuth angle from −60° ≤ γ ≤ 60°. For losses smaller than 5% of irradiation, the azimuth angle can oscillate between ±30° without a significant impact on the total irradiation captured by a flat solar collector.