In this study, we explored Photovoltaic-Thermoelectric (PV-TE) systems in-depth, addressing complexities in both steady-state and annual transient performance under realistic conditions. The analysis involved twelve distinct PV-TE configurations featuring diverse thermoelectric designs incorporating various semiconductors, multi-staging, non-uniform cross-sections, and material segmentation. Model 6, the PV-TE system with a multi-stage segmented rectangular design, emerged as the top performer, exhibiting a remarkable 12% increase in electric power output during peak sunlight compared to the base model, despite a marginal decrease in efficiency. Furthermore, this research delved into the potential of advanced nanofluid cooling, investigating options such as distilled water, titanium oxide, aluminum oxide, iron oxide, and graphene. The results underscores graphene nanofluid's superiority, demonstrating a significant enhancement in thermal management at an optimal flow velocity of 2 m/s. This improvement in thermal management refers to the effective heat dissipation and temperature control within the PV-TE system. This study underlines the critical role of strategic system design and component selection in optimizing the performance of PV-TE systems. By providing a comprehensive foundation for future developments in effective and sustainable energy solutions, this research contributes to advancing the understanding and implementation of PV-TE technology.