<p>This study presents a comprehensive numerical investigation into the efficiency improvement of photovoltaic (PV)-thermoelectric generator (TEG) system combined with V-trough reflectors and an advanced cooling system. The thermal management strategy employs a container filled with a phase change material (paraffin RT35HC) enhanced with single-walled carbon nanotubes (SWCNTs), complemented by pin fins and porous foam to improve heat transfer efficiency. The PV panel, positioned at a tilt angle of 36° on the southern side, was analyzed to evaluate the effects of buoyancy forces on the behavior of the cooling system. Optical simulations were conducted using SolTrace to identify the optimal reflector angle, with 70° providing the highest optical efficiency. The system demonstrated significant performance improvements under various configurations. The incorporation of the paraffin fin cooling system enhanced PV efficiency by 27.52% by the end of the process. The inclusion of buoyancy forces further increased the liquid fraction by 9.56% and 4.47% for photovoltaic–thermal (PVT) and concentrated photovoltaic–thermal (CPVT) systems, respectively. Adding fins to the cooling system improved the liquid fraction by 33.86% for PVT and 52.31% for CPVT systems. Furthermore, the presence of reflectors, when combined with the fin-paraffin cooling system, amplified electrical power output by 2.48 times compared to the baseline scenario. The thermal and electrical efficiencies saw remarkable enhancements, with the thermal efficiency increasing by 33.75% and 47.88% in the absence and presence of reflectors, respectively, when the cooling zone was equipped with fins and porous foam. Notably, the total system efficiency, combining both thermal and electrical contributions, was 2.58 times greater than a traditional PV system without cooling. The optimized configuration produced 3.05 times more power than the baseline case.</p>