Development of a low-cost wireless data logging Pyrano-meter with inbuilt temperature and humidity monitoring system

Abstract

A low cost photodiode-based pyrano-meter with an in-built temperature and humidity monitoring system, robust data-logging, long-range wireless interface to an indoor unit capable of measuring solar irradiance, instant temperature, and relative humidity was designed, developed and tested in this study. The work was carried out in Osun State University, Osogbo. The newly developed pyrano-meter comprises two sub-systems: Indoor Unit and Outdoor Unit. The Outdoor Unit is built around BPW21R- planar Silicon PN photodiode. The indoor unit uses PIC18F2550 as the central controller. The Solar radiation, Temperature, and Relative Humidity data received from the Outdoor unit were stored in an SD Card Memory, a reference for calibration and contrast, the SRS 100 pyrano-meter was used. A 73 ± 0.55 Wm−2 calibration constant was achieved. The stability of the systems built was comparable to the SRS 100 on an open day - a sky test that gave the device irradiances of 629 and 648 Wm−2 at 6 p.m. The pyrano-meter was tested with actual metrological standard value and it provides good results.

Keywords

• Photodiode
• Pyrano-meter
• Outdoor unit
• Solar radiation
• Wireless