Low-cost Arduino-based pyranometer measuring global, direct, and diffuse solar radiation (11 citations).
Simulated live data from a low-cost Arduino-based pyranometer. The instrument uses a photodiode sensor with appropriate spectral filtering to measure global solar irradiance.
Accurate solar resource measurement is essential for PV system design and performance monitoring — but commercial pyranometers range from $500 to over $2,000, putting them out of reach for educational institutions, small installers, and research groups in developing regions.
Without reliable irradiance data, PV systems are often oversized or undersized, leading to unnecessary cost or inadequate performance. While DIY alternatives exist, most lack proper calibration procedures that would make the data scientifically useful.
There was a clear need for a low-cost instrument with documented calibration methodology — something a researcher could build, calibrate against a temporary commercial instrument loan, and then trust for ongoing measurements.
A DIY pyranometer costs ~$45 in components compared to $490–$2,100 for commercial instruments, making solar resource measurement accessible for educational and small-scale applications.
The instrument uses a BPW34 photodiode sensor with spectral filtering to approximate the solar spectrum response. An Arduino Uno microcontroller reads the sensor output, processes the analog signal, and logs data to an SD card via SPI interface. A 16x2 LCD display provides real-time irradiance readings in the field.
Sigit developed the Arduino firmware for data acquisition, implemented the calibration algorithm that maps sensor voltage to irradiance (W/m²) using a linear regression fit against a commercial reference pyranometer, and created the uncertainty analysis methodology. The calibration procedure requires only temporary access to a commercial instrument for a one-time reference measurement session.
The system samples at 1 Hz with a measurement range of 0–1200 W/m². Under clear-sky conditions, accuracy reaches ±5% of the commercial reference. The design emphasizes accessibility: all components are available through standard electronics distributors, the firmware is open-source, and the calibration protocol is documented step-by-step for replication by other researchers.
The DIY pyranometer achieved R² = 0.98 correlation with a Kipp & Zonen CMP3 commercial reference. The ±5% error band indicates reliable performance under clear-sky conditions, sufficient for educational and preliminary site assessment applications.
The DIY pyranometer achieved a correlation coefficient (R²) of 0.98 with a Kipp & Zonen CMP3 commercial reference under clear-sky conditions. Calibration procedures reduced systematic errors to within ±5% of reference measurements across the full 0–835 W/m² range tested.
The open-source calibration methodology enables replication by other researchers with access to temporary commercial instrument loans. A one-day calibration campaign against a reference pyranometer produces a transfer function that remains valid for the sensor lifetime under normal operating conditions.
The instrumentation system was designed following a systematic methodology. The BPW34 photodiode was selected for its spectral response covering most of the solar spectrum (430–1100 nm), low cost, and wide availability. A transimpedance amplifier converts the photocurrent to a voltage suitable for the Arduino's 10-bit ADC.
Calibration was performed through simultaneous measurements with a commercial reference pyranometer over multiple days at Universitas Airlangga, Surabaya. Measurements covered morning, solar noon, and afternoon periods to capture the full irradiance range. Linear regression established the transfer function from raw ADC counts to irradiance (W/m²).
The uncertainty analysis considered sensor noise, ADC quantization error, reference instrument accuracy, and environmental factors including temperature drift and cosine response at low sun angles. Combined standard uncertainty was calculated per ISO/IEC Guide 98-3, giving users a transparent assessment of the instrument's capabilities and limitations.
Bulletin of Electrical Engineering and Informatics (BEEI), 2022
DOI: 10.11591/eei.v11i6.4390
Uses solar irradiance data from pyranometer measurements as the foundation for the peak sun hour methodology.
Relies on pyranometer-derived solar resource data for sizing the off-grid PV system in Pasuruan.
Shares the same low-cost instrumentation philosophy for accessible rural energy solutions.
This instrumentation work provides the solar measurement foundation for sigit's subsequent applied projects in renewable energy assessment and PV system design.