Hybrid photovoltaic-thermoelectric systems for solar energy harvesting – HYDRES

Despite recent conceptual and technological advances, the conversion efficiency of single-junction solar cells is still limited to 33%. In particular, depending on the photovoltaic material, up to 50% of the solar energy striking the cell is lost and dissipated as heat. An emerging strategy for harvesting this waste energy is to couple the solar cell with a thermoelectric generator (TEG) into a hybrid photovoltaic-thermoelectric (PV-TE) system. The first experimental realizations of hybrid PV-TE systems, though simple, show a promising gain in efficiency of up to +5%. In the frame of the HYDRES project, we propose a global and multidisciplinary approach to overcome the technological barriers hindering the development of highly-efficient hybrid systems. In particular, HYDRES aims at demonstrating that PV-TE hybridization can be used to improve the conversion of solar energy while keeping the device compact, thereby paving the way towards self-sufficient embedded systems.
In order to design and realize an optimal architecture for PV-TE systems, the key challenges that will be addressed by HYDRES are (1) building a comprehensive physical model of the hybrid system supported by experimental data, including two aspects often overlooked in current models, that is, the physical interface between the solar cell and the TEG and the electronic interface dedicated to handle the electrical connection of the two power sources and track the maximum electrical power point; (2) integrating a photovoltaic cell and a TEG specifically designed for optimal PV-TE hybridization; (3) functionalizing the interface between the solar cell and the TEG to boost the heat flow incoming in the thermoelectric module and its contribution to the output power of the PV-TE system; (4) developing a technological process to fabricate a PV-TE device with a high thermal coupling. The advances made in the context of HYDRES should impact significantly the research field by providing generic guidelines for the design of optimal PV-TE systems, based on any photovoltaic or thermoelectric materials.
HYDRES will exploit the synergy between researchers from different scientific communities (thermo-plasmonics for photovoltaics at LAAS-CNRS, thermoelectric technology (Materials with Thermoelectric Properties team at IJL) and smart electronics (Electronic Measures and Architectures team at IJL)) who gather the ideal know-how and expertise to carry out this first joint experimental and theoretical study exploring the global optimization of hybrid PV-TE systems through a comprehensive multidisciplinary approach.