Energy efficiency is one of the biggest concerns nowadays. During the last months, a drastic increase of the electrical energy prices has been seen. The main causes are two: the strong revaluation of natural gas on international markets and the rise of the CO2 emission market prices. Therefore, reducing dependence on fossil fuels is a matter of urgency. The reduction of electricity consumption would help in following this direction. The use of natural illumination in buildings could play a vital role for decreasing the energy dependency, hence it is essential to measure the solar illuminance. Professional sensors cost hundreds of euros. This work compares several illuminance sensors for Internet of Things (IoT) projects against a professional one. The former ones cost just a few euros. The results show good precision and regular accuracy.
