Energy crisis and carbon emissions are two increasingly prominent issues in our society. As one of the clean energy sources, thermoelectric power generation is a promising alternative energy technology to convert heat into electricity. As long as there is a heat source, thermoelectric generators can provide electricity for watches, sensors, electronics, spacecraft, etc., and can also be used to recover waste heat, such as automobile exhaust heat, industrial waste heat, ship waste heat, etc. This study proposes a novel classification paradigm based on power output (microwatt, 1 W–1 kW, >1 kW), systematically revealing the technological characteristics at each power level: the microwatt level relies on flexible materials and compatibility with human body heat, while the kilowatt level requires the integration of high-temperature materials and optimized thermal management. The study also demonstrates that performance can be significantly enhanced through asymmetric geometric designs and non-equilibrium synthesis processes. This work provides a comprehensive design framework, from material innovation to large-scale integration, for next-generation thermoelectric systems, addressing the theoretical gap in techno-economic analysis.