The use of thermoelectric generators (TEGs) to recover useful energy from waste heat has increased rapidly in recent years with applications ranging from microwatts to kilowatts. Several thermoelectric modules can be connected in series and/or parallel (forming an array) to provide the required voltage and/or current. In most TEG systems the individual thermoelectric modules are subject to temperature mismatch due to operating conditions. Variability of the electro-thermal performance and mechanical clamping pressure of individual TEG modules are also sufficient to cause a significant mismatch. Consequently, when in operation each TEG in the array will have a different electrical operating point at which maximum energy can be extracted and problems of decreased power output arise.

This work analyses the impact of thermal imbalance on the power produced at module and system level in a TEG array. Experimental results clearly illustrate the issue and a theoretical model is presented to quantify the impact. The authors believe the experimental results presented in this paper are the first to validate a rigorous examination of the impact of mismatched operating temperatures on the power output of an array of thermoelectric generators.