Overcoming the efficiency dilemma in PV-TEG hybrid systems: A multi-domain critical review and 4E roadmap for commercialization

Photovoltaic-thermoelectric (PV-TEG) hybrid systems represent a promising pathway to surpass the Shockley-Queisser limit by converting solar cell waste heat into additional electricity. However, their practical implementation faces a persistent "efficiency dilemma": the thermal resistance introduced by integrating a TEG onto a PV cell can inadvertently elevate the cell's operating temperature, yielding a net electrical gain only when the TEG's supplementary power exceeds the PV's thermally induced loss ( P TEG − Δ P PV ). This comprehensive critical review systematically analyzes recent advancements across 4 interconnected domains: (1) advanced thermal management using nanofluids and nano-enhanced phase change materials, reaching >70% thermal extraction efficiency (heat removed per incident solar energy) while net electrical conversion remains below 25% under standard test conditions (STC); (2) intelligent control strategies employing meta-heuristic algorithms that improve power output by >30% under partial shading in hardware-validated tests; (3) system-level optimization through optical concentration and spectrum splitting, where thermodynamic modeling indicates up to 86% total power increase over non-concentrated configurations, though long-term field validation remains limited; and (4) emerging applications in solar desalination and building integration that leverage the thermal output stream to improve system-level economics. Unlike prior reviews that assess PV and TEG performance independently, this work introduces a dual-assessment methodology: every technology domain is simultaneously benchmarked by a Technology Readiness Level (TRL) classification with explicit justification criteria and a quantitative 4E (Energy, Exergy, Economic, Environmental) analysis normalized to STC. This paired framework reveals that the most commercially viable near-term pathway lies not in maximizing individual component efficiency, but in optimizing the interface between mature technologies—passive cooling at TRL 7–9 and dual-Maximum Power Point Tracking (MPPT) control at TRL 6–8—with standardized, pressure-optimized thermal interface materials. The review concludes with a 3-phase R&D roadmap (Interface Standardization, Integrated System Validation, Multi-Output Commercial Deployment) specifying quantitative milestones for TRL advancement, cost reduction, and durability targets to transition PV-TEG systems from laboratory prototypes to commercially viable renewable energy solutions.