Process heat generation is an unexploited application for solar thermal systems despite its large potential. Solar thermal systems can achieve higher system yields in industrial applications compared to domestic ones. At the same time, systems can be more complex in industrial applications because of the variety of heat consumers, hydraulic setups and temperature levels. In order to design and operate solar process heat systems efficiently and to exploit the large potential, possible faults of such systems and their impact have to be evaluated. In this paper, an implemented solar process heat system is methodically analyzed based on monitoring data and simulations with a validated model. Several faults are identified and their influence, as well as, the influence of a reduced load on the system yield is evaluated. The analysis shows that the reduced load is most influential and that the expected system yield can be reached if all faults are eliminated. Further, the most important impact factors on the system performance are identified: the collector parameters (eta(0), a(1)) and load characteristics (mass flow, temperature). (C) 2013 Elsevier Ltd. All rights reserved.