This paper presents an experimental study of a STEG (solar thermoelectric generator) working at high concentration ratio (>100) and high temperature (>= 450 degrees C). An indoor characterization set-up based on Si80Ge20 thermoelectric material coupled with a selective absorber and a solar concentrating simulator was developed. The goal was to validate a physical model allowing to predict performances of such thermoelectric material for much higher temperatures. Predictive efficiencies were thus extrapolated for a working temperature beyond 800 degrees C. The critical issue deals with the best system dimensioning taking into account the concentrator size, and the efficiency versus the TEG (thermoelectric generator) size. (C) 2015 Elsevier Ltd. All rights reserved.