Lightweight, low-cost, automatic monitoring of global and diffused solar radiation

Abstract

　A lightweight, low-cost automatic operating system was developed for monitoring global and diffused solar radiation. To measure solar radiation received by a plant canopy more accurately, a spherical photodiode is used instead of flat sensors.
　Calibration was conducted with comparison to the output of a standard solarimeter, which was faced towards the sun's disk, thereby minimizing effects of the cosine law, which strongly affects flat sensors. Good correlation was obtained between the output of the developed system and solar radiation. An Excel spreadsheet (Microsoft Corp.) was developed to extract diffused radiation data from the original data sheets, which have global and diffused radiation in sequence.