73% of the global CO2 emissions are generated by the energy sector (including transport and buildings). Electrification, combined with power generation using low carbon, renewable energy sources represent a viable path to tackle climate change. In this context, solar power represents today, not only the cheapest energy source, but also the quickest to deploy. Solar power installations, particularly PV have been growing exponentially, a trend which is expected to continue especially considering the fluctuating and volatile gas and oil markets. In an energy system, where solar photovoltaic power will represent the major energy source (potentially up to 69% of the global energy supply by 2050), the need to understand, improve and forecast the operations of PV plants becomes critical for the security and safety of the society. CACTUS proposes to improve the research infrastructure (RI) and its portfolio of services for an enhanced solar PV performance, particularly adapted for various climate conditions (such as tropical, desert, temperate), considering the whole lifetime of PV projects, from design, installation, operations, decommissioning and End of Life. This will be achieved by linking outdoor and indoor measurements with physical parameters based on material analysis, improving algorithms for O&M, developing common data treatment procedures, assessing sustainability related aspects, while enhancing bi-regional scientific cooperation (EULATAM) in the renewable energy sector.