OPTIMUM SOLAR PANEL TILT ANGLE FOR MAXIMUM ANNUAL IRRADIATION

This work presents a simple numerical model, based on a spreadsheet, to optimize solar panel tilt angle for given panel azimuth angle. This approach uses ASHRAE's solar irradiation model, which presents a comprehensive model for calculating solar irradiation based on direct, reflected, diffuse and scattered components of solar irradiation. It includes the atmospheric extinction coefficient and sky clearness number (index). By calculating the monthly total irradiation from January to December the present model calculates the total annual irradiation on an incline solar panel. Then by implementing spreadsheet's solver, the tilt angle to yield maximum annual solar irradiation per square area of panel is evaluated. Due to its general formulation the present model can be used to optimize solar tilt angle for any location (latitude) as long as the clearness index and ground reflectivity are known. The results of this model were compared with some existing location specific optimum tilt angles. The results are comparable within three degrees of tilt angle.