Creating a Solar Radiation Measuring System (SRMS) Operated by a Programmable Logic Controller (PLC)

Abstract

In this study, it is aimed to create a PLC controlled SRMS to be used in rural areas. Firstly a SRMS hardware was prepared consisting of power supply, PLC, analogue module and pyranometer units. Then, a SRMS software was written using CODESYS programming language to measure and record data and to control the hardware by PLC. SRMS software firstly collected the solar radiation in cumulatively by measuring every 30 minutes during the one-day period, and determined the daily total solar radiation. Then it calculated the daily average solar radiation by dividing the daily total solar radiation by the number of measurements. It recorded the daily total and average solar radiation amounts on the SD card. SRMS was tested in Kahramanmaraş Sütçü İmam University (KSU) during the July-November period of the 2019. The daily average solar radiation data recorded at KSU were compared with the data measured in the same period at the Eastern Mediterranean Transition Area Agricultural Research Institute (DAGTEM), located 10 km away. The daily average solar radiation data measured in KSU and DAGTEM varied between 3.63-33.48 MJ m-2 day-1 and 3.00-33.00 MJ m-2 day-1, respectively. Five-month averages of daily solar radiation data measured at both regions were determined 20.20 MJ m-2 day-1 and 19.64 MJ m-2 day-1, respectively. The difference between the mean of KSU and DAGTEM data groups was not found to be statistically significant (p> 0.05). This result revealed that the daily average solar radiation values measured in both regions can be used interchangeably. As an expression of the deviation between data groups measured in both regions, the MAPE and RMSE were determined as 14.57% and 2.68 MJ m-2 day-1. The compatibility level of the data groups was obtained as “good” (MAPE= 10-20%). It was concluded that SRMS could measure the daily average solar radiation with high accuracy and could be used in sensitive measurements.