Cement-Based Radiative Coolers for Photovoltaics: Towards a Practical Design

In 2014, the experimental realization of radiative coolers capable of reaching sub-ambient temperatures under direct sunlight has opened up new possibilities for the thermal management of solar cells. Radiative coolers eject excess heat by emitting thermal radiation within the so-called atmosphere transparency window. The completely passive nature of this process and its reliance on material properties only, make radiative coolers extremely attractive in terms of energy efficiency. Integrated with a photovoltaic cell, the radiative cooler can reduce the cell operating temperature, leading to high efficiency and lifetime gains. Yet, most radiative coolers in the literature are metamaterials with scarce elements or complex fabrications processes, or organic materials with potential UV instability, with questionable economic viability or reliability. To address this problem, we have recently proposed cement-based materials as a low-cost, scalable and stable solution for photovoltaics cooling, showing that their electromagnetic properties can be tuned to maximize their thermal emissivity by acting on their microstructure. In particular, using a detailed balance model, we have demonstrated that their cooling performance could increase the efficiency of silicon solar cells by up to 9% and extended their lifetime by up to 4 times. In this work, we take a further step towards the experimental realization of this attractive concept, by investigating possible approaches, requirements and prospects for the practical design of photovoltaic systems employing cement-based radiative coolers.