Solar cell (SC) technology is one of the most prominent solutions for renewable, sustainable and eco-friendly energy, attracting a great scientific, technological, ecological and socio-economic interest. Despite this interest, SC technology has not still demonstrated its full potential. A considerable issue affecting the SC performance, especially in the case of next generation SCs composed of sensitive materials (e.g. organic or perovskites), is the increased heating, which highly affects both solar cell efficiency and lifetime. Passive radiative cooling (PRC), a newly proposed concept leveraging the thermal radiation emission at the atmospheric transparency window in mid-IR, has been shown recently to offer a promising approach to the mitigation of solar cell heating. Its impact though on the photovoltaics (PVs) efficiency has not been thoroughly investigated, due to the complexity of such coupled electric-thermal-optical systems, neither experimentally demonstrated. MultiCool project, exploiting the PRC concept and other photonic approaches for heat management and reduction in PVs, aims the design, development and demonstration of ultrathin, lightweight and flexible photonic structures/coolers that can be integrated into solar cells and provide a significant temperature-decrease and efficiency-enhancement, in particular in the case of perovskite and organic SC architectures. The coolers design will be based on our recently developed comprehensive coupled opto-electro-thermal modeling, which is able to connect the absorption/emission/reflection properties of a SC with its temperature and efficiency; the coolers fabrication will be based on our great expertise in modern and cost-effective largescale nanofabrication techniques, such as nanoimprint lithography. With the proposed coolers the project aims beyond state of the art efficiencies in certain PV modules, such as perovskite PVs, enabling their viability and faster penetration in the market.