A solar BESS system integrates solar panels with a battery energy storage unit to capture excess solar power generated during the day and discharge it when sunlight is unavailable or electricity demand peaks. How and when do we ensure reliability? = large variety in performance, reliability and O&M requirements! Data can be available for performance analysis throughout the BESS hierarchy. An example of an AC-coupled PV + BESS. Battery ageing strongly affected by the use case it is set up to perform!Battery Energy Storage Systems (BESS) have emerged as a solution, capable of storing excess electricity and releasing it when needed, thereby ensuring a stable power supply and enhancing grid reliability and resilience. Co-located assets offer a synergistic approach to maximise revenue generation. What is BESS? The battery energy storage system comprises advanced rechargeable batteries integrated with state-of-the-art technology and software, offering a comprehensive solution for the storage. Researchers have modeled a hybrid financing scheme combining contracted and merchant components to improve the bankability of PV-battery energy storage system (PV-BESS) assets, using a Bayesian LSTM forecast integrated with a MILP optimization model to assess performance.