Investigation of temperature variations across the hot and cold sides of cascaded thermoelectric generator (CTEG) configurations in PV-CTEG hybrid systems

Cascaded thermoelectric generators (CTEGs) are increasingly used to enhance energy generation in photovoltaic (PV) cells under concentrated solar irradiance. However, research on temperature variation patterns on both sides of CTEGs, due to nonuniform irradiance and imperfect cooling, is limited. This paper explores a circular pattern, a central circular region surrounded by concentric rings, alongside a constant temperature. Experiments were conducted on PV-1,2,3-CTEG hybrid systems under irradiances of 230, 199, and 153 suns, using InGaP/InGaAs/Ge cells on Bi 2 Te 3 -CTEGs with water-cooled heat sinks. The current-voltage characteristics, short-circuit current (I sc ), open-circuit voltage (V oc ), and maximum power (P max ) were measured and compared with simulated results. The total P max generated by the 1,2,3-CTEG configurations was 0.488 W, 0.718 W, and 0.461 W, respectively. Using COMSOL Multiphysics, the 1,2,3-CTEG configurations were simulated under three scenarios: (1) constant temperature on both sides, (2) a circular pattern on the top side, and (3) a circular pattern on both sides. Comparing the total P max for the 1,2,3-CTEG configurations across scenarios (1)–(3) with experimental data, scenario (2) showed the closest alignment, with differences of 1 %, 5 %, and 10 %, respectively. This alignment was confirmed by the root mean square errors (RMSE), calculated as 0.178, 0.034, and 0.044 for scenarios (1)–(3), respectively.