Feasibility of Photosynthetically Active Radiation (PAR) Measurement Using LED and Photodiode

Photosynthetically Active Radiation (PAR) is measured by high costs commercial PAR sensors.The feasibility of economical PAR measurements became crucial since sensing numerous data instantaneously has great importance of making right decisions for applications in precision farming. Therefore, achieving successful lighting applications based on precision farming rules at greenhouse depends on making real-time, enough, multiple photosynthetically active radiation (PAR) measurement economically. The main objective of this study was to find out a cheap and easy device to substitute for commercial PAR sensors. For this purpose, the ability of utilization LEDs, powerLEDs and photodiodes which are opto-electronic equipment was investigated. Eight LEDs, three powerLEDs and two photodiodes with different specifications were tested during the experiments in order to determine feasibility of PAR measurements. The necessary experiments were carried out at Regional Meteorological Service in Izmir. The test units and equipments were designed and mounted on Automated Weather Observation System (AWOS). According to experiments results, powerLEDs and photodiodes revealed unfavourable results. On the other hand, the five out of eight LEDs were found to be 99 % correlated with PAR sensor measurements during the sunny days. The LED-B and LED-C have strong correlation coefficient of 99.2% and 99.7 %, respectively even in cloudy and rainy days. It was concluded that the use of LED-B and LED-C could substitute for PAR sensors in agricultural mechanization applications.