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The present research aimed the development and the evaluation of a low cost photovoltaic pyranometer, built from easily found materials in the national market. Therefore, models of small polycrystalline silicon photovoltaic modules were evaluated. A pyranometer body prototype with was developed with machined engineering plastic. Also, the behavior of diffusers built with three different materials Thecnyl®, acrylic and polyvinyl chloride were analyzed. For the chosen one, two distinct thicknesses were tested, as well as polished and matte surface finishing. All the tests were performed in the field, in the Federal University Rural of Semiarid weather station, from Mossoro-RN, between 2017 august and 2018 march. The prototypes results were compared to a secondary class reference pyranometer. The experiments data were collected by an automatic datalogger and its handling was accomplished considering the regulation ISO 9847:1992 recommendations. The prototype final model has shown a satisfactory performance considering measurements in the hourly and daily scales. In the total hourly values measurements, considering the interval of 6 a.m. to 6 p.m., the absolute percentage relative error was 2,26%, the minimum was 0,433% and the maximum was 8,10%. In the total daily values, the absolute percentage relative error was 0,50%, the minimum was 0,16% and the maximum was 0,93%. |
