Prototype based on a low-cost solar transducer for monitoring solar irradiance

This study focused on the design, construction, and calibration of a low-cost ($150) portable digital pyranometer prototype for monitoring global solar irradiance in Sullana-Piura-Peru. Solar radiation in northern Peru is intense in the summer and has increased significantly in recent years due to climate change. The prototype was used to monitor solar irradiance in three stages: detection, conversion, and visualization. First, solar irradiance was converted into an electrical signal using a 65 mm photovoltaic cell, an analog-to-digital (ADC) converter, and an ATMega328P microcontroller. The data were then digitized and stored in internal memory and on a microSD card. The measurements were displayed in real time on an OLED screen and transmitted via Bluetooth to an external device for one month. To calibrate the device, the irradiance values were compared with those of the standard CM21 pyranometer (ISO 9060) according to ISO 9847. The results showed that the calibration curve error was 1% when the internal cell temperature was ≤ 40°C and increased to 7% between 55°C and 65°C. In conclusion, the prototype portable digital pyranometer is feasible for use in measuring under controlled temperature conditions.