ABSTRACT:The determination of the local solar irradiance and its annual change, well as quantification of atmospheric optical thickness (EOA) is important to assess environmental conditions and air quality in a given region, with multiple practical applications. In this paper we evaluate the performances of irradiance and calculate the atmospheric optical thickness in the city of Valencia (Venezuela). The irradiance measurements are performed by implementing a set of digital pyranometers, simply constructed using LEDs as photosensor elements, and record the solar elevation angle. The average values of irradiance for the city of Valencia (Venezuela) are of 805 W/m² for 620 nm and 249 W/m 2 at 472 nm with maximum irradiance values at 12:31 and 12:18 respectively HLV, the average EOA sample, a minimum true astronomical midday (12:02 HLV). We conclude that the local variation in irradiance is correlated with the atmospheric optical thickness and irradiance in the blue band of the spectrum is predominantly diffuse, and contribution in the red band is the combination of the direct and diffuse components.