VALHALLA will develop perovskite solar cells and modules with power conversion efficiencies above 26% (23% for modules) and an extrapolated lifetime > 25 years, guided by eco-design principles that decrease the environmental impact of perovskite photovoltaics: scalable production processes, no harmful solvents, optimised use of materials, circularity and recyclability. Only lead-based perovskites have demonstrated efficiencies and stabilities that enable to reach the targeted performance levels. Therefore, in VALHALLA we focus primarily on lead based perovskites. We will develop innovative encapsulation methods containing lead-chelating materials that detain all lead even in broken modules. Circularity will be demonstrated, including a full end-of-life recovery of lead. We will focus on vacuum and hybrid processing that eliminates the use of toxic and harmful solvents during production. To increase the range of application of this sustainable technology, VALHALLA will develop rigid, flexible and semi-transparent perovskites with three bandgap ranges together with their optimized charge transport materials. Understanding the degradation mechanisms of both cells and modules in outdoor operating conditions and developing meaningful accelerated indoor stability tests for perovskite will be a key target of VALHALLA. The approach to stability will be from a global angle, from the theoretical understanding of the role of perovskite defects, composition, and architecture on the intrinsic stability to the development of module encapsulation and interconnection design that will enable long operational lifetime. An energy yield assessment will be performed based on outdoor stressed modules in three different European locations.