Abstract Interest in collecting waste heat from diesel generators, a substantial but underutilized energy source, has increased due to the growing demand for energy efficiency. By transforming heat gradients into electrical power, thermoelectric generators (TEGs) offer a clean alternative that improves fuel efficiency and lowers pollutants. In order to improve thermoelectric power generation, this work intends to construct and assess a hybrid system that combines Heating, Ventilating, and Air Conditioning (HVAC) condenser airflow with waste heat from diesel generator exhaust gases. The suggested system presents a new architecture that makes simultaneous use of condenser air and diesel exhaust, two easily accessible but infrequently coupled thermal sources and sinks. Compared to conventional setups, this method greatly increases TEG efficiency by taking advantage of high temperature differentials and passive sink flow. To mimic the behavior of the system under various operating situations, we developed a comprehensive thermal model. The effect of TEG plate dimensions, duct heights, and the TEG thickness-to-thermal-conductivity ratio (t/k) on temperature gradients and power output were investigated parametrically. The findings indicate that while larger cooling loads from the HVAC system result in worse performance, increasing the generator load and t/k ratio increases power output. With duct height = 0.04 m and a 5 m × 0.2 m TEG plate, the optimized arrangement produced a peak output of 4745 W, which translates to a 2.37 % increase in fuel efficiency. This work provides a scalable model for sustainable energy integration in industrial applications and validates the potential of hybrid TEG systems for efficient waste heat recovery.