Open-Source Smart Wireless IoT Solar Sensor
Source abstract
Abstract
IoT (Internet of Things)-enabled solar irradiance sensors are evolving toward energy harvesting, interoperability, and open-source availability, yet current solutions remain either costly, closed, or limited in robustness. Based on a thorough literature review and identification of future trends, we propose an open-source smart wireless sensor that employs a small photovoltaic module simultaneously as sensing element and energy harvester. The device integrates an ESP32 microcontroller, precision ADC (Analog-to-Digital converter), and programmable load to sweep the PV (photovoltaic) I–V (Current–Voltage) curve and compute irradiance from electrical power and solar-cell temperature via a calibrated third-order polynomial. Supporting Modbus RTU (Remote Terminal Unit)/TCP (Transmission Control Protocol), MQTT (Message Queuing Telemetry Transport), and ZigBee, the sensor operates from batteries or supercapacitors through sleep–wake cycles. Validation against industrial irradiance meters across 0–1200 W/m2 showed average errors below 5%, with deviations correlated to irradiance volatility and sampling cadence. All hardware, firmware, and data-processing tools are released as open source to enable reproducibility and distributed PV monitoring applications.
Source: crossref · Quality: baseline
Research context
OpenAlex topics: IoT-based Smart Home Systems
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Electronics and Telecommunications Department, Faculty of Transports, National University of Science and Technology POLITEHNICA Bucharest, Splaiul Independenței 313, 060042 Bucharest, Romania
Computer Science and Engineering Department, Faculty of Automatic Control and Computers, National University of Science and Technology POLITEHNICA Bucharest, Splaiul Independenței 313, 060042 Bucharest, Romania
Funding
National Program for Research of the National Association of Technical Universities
References (54)
Show source-provided references
1. International Renewable Energy Agency (IRENA) (2023). World Energy Transitions Outlook 2023: 1.5 °C Pathway, International Renewable Energy Agency.
2. Fraunhofer Institute for Solar Energy Systems ISE (2023). Photovoltaics Report, Fraunhofer Institute for Solar Energy Systems ISE.
3. International Energy Agency (IEA) (2022). World Energy Outlook 2022.
4. (2017). Photovoltaic System Performance—Part 1: Monitoring (Standard No. IEC 61724-1:2017). Technical Report.
5. Estimating PV Module Performance over Large Geographical Regions: The Role of Irradiance, Air Temperature, Wind Speed and Solar Spectrum10.3390/en8065159 ↗
6. Kratochvil, J.A., Boyson, W.E., and King, D.L. (2004). Photovoltaic Array Performance Model.10.2172/919131 ↗
7. (2018). Solar Energy, Specification and Classification of Instruments for Measuring Hemispherical Solar and Direct Solar Radiation (Standard No. Standard ISO 9060).
8. (2021). Photovoltaic System Performance—Part 1: Monitoring (Standard No. IEC 61724-1:2021). Technical Report.
9. Sengupta, M., Habte, A., Wilbert, S., Gueymard, C., and Remund, J. (2021). Best Practices Handbook for the Collection and Use of Solar Resource Data for Solar Energy Applications: Third Edition.10.2172/1778700 ↗
10. Driesse, A., Gotseff, P., and Sengupta, M. (2022). PV Reference Cells for Outdoor Use: Comparison of First-Year Field Measurements.10.2172/1866986 ↗
11. Improved field evaluation of reference cells using spectral measurements10.1016/j.solener.2020.12.063 ↗
12. An accurate real time neural network based irradiance and temperature sensor for photovoltaic applications10.1016/j.rineng.2024.101766 ↗
13. Khalid, W., Jamil, M., Khan, A.A., and Awais, Q. (2024). Open-source internet of things-based supervisory control and data acquisition system for photovoltaic monitoring and control using HTTP and TCP/IP protocols. Energies, 17.10.3390/en17164083 ↗
14. A smart energy monitoring system using ESP32 microcontroller10.1016/j.prime.2024.100666 ↗
15. Witczak, D., and Szymoniak, S. (2024). Review of monitoring and control systems based on Internet of Things. Appl. Sci., 14.10.3390/app14198943 ↗
16. Industrial IoT-Based Energy Monitoring System: Using Data Processing at Edge10.3390/iot5040027 ↗
17. IoT-based real-time monitoring system for a smart energy house10.2352/ISSN.2470-1173.2021.3.MOBMU-038 ↗
18. Ramadhan, J.M., Mardiati, R., and Haq, I.N. (2021, January 19–20). Iot monitoring system for solar power plant based on mqtt publisher/subscriber protocol. Proceedings of the 2021 7th International Conference on Wireless and Telematics (ICWT), Bandung, Indonesia.10.1109/ICWT52862.2021.9678503 ↗
19. Smart Monitoring of Photovoltaic Energy Systems: An IoT-Based Prototype Approach
20. Calderón, D., Folgado, F.J., González, I., and Calderón, A.J. (2024). Implementation and experimental application of industrial IoT architecture using automation and IoT Hardware/Software. Sensors, 24.10.3390/s24248074 ↗
21. Modeling and simulation of a 3 kw photovoltaic system for an autonomous consumer
22. Demir, B.E. (2023). A New Low-Cost IoT Based Monitoring System Design for Stand-Alone Solar Photovoltaic Plant and Power Estimation. Appl. Sci., 13.10.20944/preprints202309.0158.v1 ↗
23. Hamied, A., Mellit, A., Benghanem, M., and Boubaker, S. (2023). IoT-Based Low-Cost Photovoltaic Monitoring for a Greenhouse Farm in an Arid Region. Energies, 16.10.3390/en16093860 ↗
24. A low-cost system for real-time measuring of the sunlight incident angle using IoT10.1016/j.ohx.2022.e00272 ↗
25. Nava-Pintor, J.A., Alcalá-Rodríguez, U.E., Guerrero-Osuna, H.A., Mata-Romero, M.E., Lopez-Neri, E., García-Vázquez, F., Solís-Sánchez, L.O., Carrasco-Navarro, R., and Luque-Vega, L.F. (2025). Development and Evaluation of Solar Radiation Sensor Using Cost-Effective Light Sensors and Machine Learning Techniques. Technologies, 13.10.3390/technologies13050182 ↗
26. Abe, C.F., Dias, J.B., Notton, G., and Faggianelli, G.A. (2020). Experimental Application of Methods to Compute Solar Irradiance and Cell Temperature of Photovoltaic Modules. Sensors, 20.10.3390/s20092490 ↗
27. Laudani, A., Lozito, G.M., and Riganti Fulginei, F. (2021). Irradiance Sensing through PV Devices: A Sensitivity Analysis. Sensors, 21.10.3390/s21134264 ↗
28. IoT and machine learning models for multivariate very short-term time series solar power forecasting10.1049/wss2.12088 ↗
29. Forecasting Photovoltaic Power Generation via an IoT Network Using Nonlinear Autoregressive Neural Network10.1016/j.procs.2019.04.086 ↗
30. Secure low-cost photovoltaic monitoring system based on LoRaWAN network and artificial intelligence10.1007/s10791-024-09475-0 ↗
31. Bueso, M.C., Paredes-Parra, J.M., Mateo-Aroca, A., and Molina-García, A. (2022). Sensitive Parameter Analysis for Solar Irradiance Short-Term Forecasting: Application to LoRa-Based Monitoring Technology. Sensors, 22.10.3390/s22041499 ↗
32. Very short-term solar irradiance forecasting based on open-source low-cost sky imager and hybrid deep-learning techniques10.1016/j.solener.2025.113516 ↗
33. Alzahrani, A. (2022). Short-Term Solar Irradiance Prediction Based on Adaptive Extreme Learning Machine and Weather Data. Sensors, 22.10.3390/s22218218 ↗
34. Machine learning-based prediction model for battery levels in IoT devices using meteorological variables10.1016/j.iot.2024.101109 ↗
35. Digi (2025, August 14). Digi XBee® 3 RF Module Hardware Reference Manual. Available online: https://docs.digi.com/resources/documentation/digidocs/pdfs/90001543.pdf.
36. Espressif (2025, August 14). ESP32-WROOM-32 Datasheet. Available online: https://www.espressif.com/sites/default/files/documentation/esp32-wroom-32_datasheet_en.pdf.
37. Instruments, T. (2025, August 14). ADS131A0x Datasheet. Available online: https://www.ti.com/lit/ds/symlink/ads131a04.pdf.
38. Instruments, T. (2025, August 14). TPS732xx-EP Datasheet. Available online: https://www.ti.com/lit/ds/symlink/tps73230-ep.pdf?ts=1755120122873.
39. Instruments, T. (2025, August 14). REF50xxA-Q1 Datasheet. Available online: https://www.ti.com/lit/ds/symlink/ref5020a-q1.pdf?ts=1755156346294&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FREF5020A-Q1%252Fpart-details%252FREF5020AQDRQ1.
40. Instruments, T. (2025, August 14). TMP11 Datasheet. Available online: https://www.ti.com/lit/ds/symlink/tmp117.pdf?ts=1755096141116&ref_url=https%253A%252F%252Fwww.google.com%252F.
41. Emelianov, A. (2025, September 11). Modbus Library for Arduino. Available online: https://github.com/emelianov/modbus-esp8266.
42. Software, W. (2025, September 11). Modbus Poll. Available online: https://www.modbustools.com/modbus_poll.html.
43. O’Leary, N. (2025, September 11). Arduino Client for MQTT. Available online: https://github.com/knolleary/pubsubclient.
44. Foundation, E. (2025, September 11). Mosquitto. Available online: https://mosquitto.org/.
45. Nordquist, T. (2025, September 11). MQTT-Explorer. Available online: https://mqtt-explorer.com/.
46. Instruments, N. (2025, August 26). USB-6009 Specifications. Available online: https://www.ni.com/docs/en-US/bundle/usb-6009-specs/page/specs.html?srsltid=AfmBOopROhAH3XUCnhV82tD60qahwT0j1oaWNLLHjanlPI_FiqTpipRM.
47. Solar, I. (2025, September 01). SI-I-420TC-T Datasheet. Available online: https://imtsolar.com/wp-content/uploads/2012/10/IMT-Sensor-Cut-Sheet-2015.pdf.
48. DATASOL MET (2025, September 01). Radiation Acquisition Manual. Available online: https://atersa.shop/app/uploads/2018/03/MU-38-T-Manual-MET.pdf?srsltid=AfmBOooTximbvR7Z6M-EUEzZNEgr5saN4p9rwAKClMC6QKldL2S7K6H_.
49. Phoenix Contact (2025, August 26). Axioline F: System and Installation User Manual. Available online: https://www.manualslib.com/manual/1536738/Phoenix-Contact-Axioline-F.html.
50. Avantech (2025, August 26). ADAM-4017 Datasheet. Available online: https://advdownload.advantech.com/productfile/PIS/ADAM-4017+/file/ADAM-4017_4018_4019_DS(092223)20230928142137.pdf.
51. Energy, J. (2025, September 08). SOLAR IRRADIANCE SENSOR SI-I-420TC-T. Available online: https://www.jedsenergy.com/products/solar-irradiance-sensor-si-i-420tc-t.
52. ATERSA (2025, September 08). Calibrated Cell 65mV Compensated (ATERSA). Available online: https://atersa.shop/celula-calibrada-0-65-mv-compensada-atersa/.
53. Fondriest Environmental, I. (2025, September 08). Kipp & Zonen SMP Series Smart Pyranometers. Available online: https://www.fondriest.com/kipp-zonen-smp-series-smart-pyranometers.htm.
54. Computer Science Department @ UPB (2025, September 24). Smart Solar Irradiance Sensor-Source Code & Schematics. Available online: https://github.com/cs-pub-ro/smart-solar-irradiance-sensor.