Understanding the dynamics of energy carriers is crucial to processes ranging from photosynthesis to photovoltaics and batteries. While carriers in the equilibrium state are well studied, perturbation of carrier dynamics by multiple independent internal and external stimuli in energy conversion devices is not understood, thus limiting the potential of high-performance materials. I will tackle foundational questions in carrier dynamics to provide the first complete picture of non-equilibrium carrier behavior under practical operating conditions, correlating simultaneous optical and electrical measurements at unprecedented spatiotemporal resolution. The findings will provide transformative insights into nanoscale behavior and interactions of multiple carriers (excitons, phonons, ions), identify key bottleneck mechanisms, and elucidate fundamental principles of carrier dynamics that will underscore new developments in energy harvesting, conversion, and storage.