Solar thermoelectric generators (STEGs) can directly harness solar energy for power generation. Experimental and numerical studies on the transient response of an oxide thermoelectric generator (TEG) to variation of solar radiation in semi-cloudy weather are carried out. In the first phase, performance of a STEG is investigated under variable solar radiation. Furthermore, effect of a self-adhesive graphite sheet attached to the hot surface of the STEG on enhancement of thermal and electrical performance is studied. In order to evaluate the system performance at high solar concentrations and high operation temperatures, numerical simulation is performed using finite volume method (FVM). I-V-P curves for both STEG systems, with and without the graphite sheet, are obtained. Variation of the hot and cold side temperatures of the TEG and maximum output power variations versus the time are presented and discussed. The results show that, the graphite absorber has a substantial effect on the power generation by the TEG by enhancement of absorbed radiation. This impact is more noticeable at higher solar concentrations and higher temperatures. (C) 2018 Elsevier Ltd. All rights reserved.