The identification of appropriate locations for photovoltaic (PV) solar power plants presents a multifaceted challenge that entails a complex interplay of diverse criteria. Algeria, which has a clear advantage in becoming a major player in the field of solar energy production, has in recent years intensified programs aimed at taking full advantage of this potential. Therefore, in order to provide the necessary assistance to the government and all the operators wishing to install photovoltaic systems in this country, this paper aims to present a research methodology that combines Geographic Information System (GIS) analysis, Multi-Criteria Decision- Making (MCDM) techniques, and off-site measurements to identify the most suitable sites for off-grid PV facilities installation across Algeria. However, before reaching the main objective, a refined digital elevation model (DEM) was developed. In addition, monthly mean values of global daily horizontal and tilted irradiance for a typical meteorological year were calculated, facilitating the mapping of these two quantities over the 12 months. Finally, the annual sum of photovoltaic energy produced by a PV power plant with a total installed capacity of 1 MWp was calculated, ranging from 1535 MWh/MWp to 2051 MWh/MWp per year depending on geographic location. The Analytic Hierarchy Process (AHP) was used to evaluate multiple criteria and prioritize the most suitable areas, classifying Algeria into seven distinct grades: "Somewhat suitable", covering 36.4030% of the total country, followed by "Moderately suitable"at 32.4613% and "Very suitable"at 11.2877%. "Marginally suitable"lands comprise 15.8632%, while "Highly suitable"and "Minimally suitable"areas account for 2.0042% and 1.7342%, respectively. The "Extremely suitable"sites cover the smallest area at 0.2463% and are located primarily in the Southeast and East-Southeast regions. The outcome of this research is an updated Solar Atlas of Algeria and a high-resolution suitability map showing the spatio-temporal variability of PV potential across the country.
