Development of a low cost pyranometer for solar radiation measurements

Abstract

This study intends to build a new model of solar pyranometer using a photosensor for radiation measurements. The system operation is based on principle know as a photoelectric effect where a material, generally a metallic one, is exposed to magnetic radiation ejecting electrons energized by this radiation. The intensity of this incident radiation must be sufficiently high but this response varies with the material and the incident wavelength. Therefore, from an electric signal generated by the photosensor is possible to get values for the incident thermic radiation. In the proposed model, a photodiode is used to generate this electrical signal. The photodiode is connected with a shunt resistor for dissipative effects. Then, the signal is amplified and can be read by an acquisition data system. The results obtained for the electric signal will be compared with the output signal of a reference pyranometer. Thus, a calibration curve will be created and the uncertain measures will be estimated.