Variability of Solar Radiation Received on Tilted Planes in Adrar Region in the South of Algeria

The solar radiation is one of the renewable energy sources that is gaining importance day by day. To make the most effective use of solar energy, the tilt angle of the solar panel that collects solar radiation must be properly adjusted. In this study, experimental and analytical investigations have been conducted in order to identify the solar panels’ optimum tilt angles for the first time in Adrar site, located on the southwestern region of Algeria, and to recommend a general approach for any location in country. Calculations were made with both selected isotropic and anisotropic models. 11 years (2010–2020) historical data in Renewable Energy Research Unit in Saharan Medium (URER-MS) was used. Monthly, seasonal, and Annual solar panels’ optimum tilt angles were determined. It is found that the annual optimum solar panel tilt angle should be set to 28°. These findings might be generalized to locations with different coordinates at the same latitude the annual variability of solar radiation on different planes of inclination is between 6 kWh/m2/day and 8 kWh/ m2/day (2010–2020) all inclinations combined from horizontal to near 60° and 2 kWh/m2 to 6 kWh/m2 for a vertical plane facing plain south.