Efficiency determination and general characterization of thermoelectric generators using an absolute measurement of the heat flow

An apparatus for measuring the conversion efficiency η and several further key properties of thermoelectric generators is presented. To achieve highest reliability and accuracy the crucial determination of the thermal energy that is supplied to the generator is done by an absolute method, i.e. by measuring the electrical power that is dissipated in a thermally guarded resistive heater. The accuracy of this method was carefully verified with a traceable calibration standard. The data evaluation is discussed for test measurements of a high efficiency Bi2Te3 module and compared to results that are estimated from the material properties. Excellent accuracy, consistency and reproducibility of the data are found, which makes the measurement a sensitive and reliable tool for the development of thermoelectric generators.