Description and Background: Performance modeling is important at every stage of the solar value chain, from feasibility studies to financing, commissioning, and operating projects. While modeling tools used during the design phase offer high precision, those incorporated into monitoring platforms are often blunt instruments, leading asset managers to overlook small overall performance deviations that could lead to headaches and lost revenue. This session will explore the levels of sophistication between performance models and detail how bottoms-up modeling can produce valuable insights at the device and string levels. Through case studies, participants will gain an appreciation of how performance models can be used to both surface and diagnose issues remotely and in real time.