Evaluating the environmental relevance of small-scale PV energy harvesting system for connected sensors through life cycle assessment

The digitization challenges of our society is leading to a growing need of data processing which means collection, storage, treatment and means therefore energy demand growth [1]. The objective of this digitalization is to constantly improve our living comfort [1]. In the same time, climate change mitigation, which is one of the biggest issues of the 21st century [2], is motivating many people to reduce their energy needs [2]. Internet of Things (IoT) sensors are a very concrete example illustrating the meeting of these two challenges [3]. At the same time, our society is thirsty for digitalization and at the same time, it wants to limit its impact on the environment by favoring renewable energy solutions [3]. One solution is to equip these IoT sensors with a solar energy harvesting system so that they are autonomous and powered by renewable energy [4]. However, is this low-power PV system really interesting environmentally if we have a global vision on the whole life cycle of the sensor? Thereby, this thesis aims to investigate the most sustainable way, from an environmen- tal point of view, to supply an IoT device. Is it better to use an photovoltaic harvesting energy equipment or connect the IoT node to a given energy mix grid? To address these challenges, first of all, a complete life cycle assessment (LCA) of the Photon from Sunslice will simulate as closely as possible the power consumption behavior of a well-defined portion of IoT sensors on the market. In a second time, a comparison of small to large scale solar installations will allow to determine or not the presence of fixed environmental costs during their entire life span. Using the detailed LCA of the Photon, we came to the conclusion that a PV harvesting system for an IoT sensor can be both interesting and inconsistent. To design sustainably a connected sensor equipped with a PV energy harvesting system, the following factors must be taken into account: the life span of the product, the available irradiation, the efficiency of the PV cells and the potential impact per kWh of the local electrical grid.