raw · articles · ingested 2026-07-19
SolarSensor — open-hardware solar irradiance sensor
Source: https://github.com/curiouselectric/SolarSensor
GitHub repository, publication date not stated.
Key findings
Uses an OSRAM SFH203 photodiode (400–1100 nm response, ~80 µA photocurrent), read through a 16-bit ADC on an ATMega328, with an LM75 I2C temperature sensor for thermal compensation of the photodiode’s ~0.18%/K temperature coefficient. A 6mm PTFE diffuser attenuates the signal so the sensor doesn’t saturate below 2,000 W/m², covering full outdoor sunlight range. Calibration is a simple linear y = mx + c stored in EEPROM (defaults m=1, c=0), adjustable via serial commands — flagged as needing reference-instrument calibration for absolute accuracy, but good enough for relative/trend measurement out of the box. Communicates over serial (works with Pi, ESP32, or Arduino) in polled or broadcast mode, and internally logs rolling averages (1s/10s/1min/10min/1hr) plus min/max.
Why it matters for this archive
A genuinely low-cost, open-source, purpose-built pyranometer alternative — directly answers the hardest instrumentation sub-question (affordable solar irradiance sensing) with a documented, buildable design rather than a vague suggestion. See Small-scale passive-thermal experiment monitoring.