Nowadays, conventional coal or gas fired power plants are the dominant way to generate electricity in the world. In recent years there is a growth in the field of renewable energy sources in order to avoid the threat of climate change from fossil fuel combustion. Solar energy, as an environmental friendly energy source, may be the answer to the reduction of global CO2 emissions. This paper presents the concept of Solar Aided Power Generation (SAPG), a combination of renewable and conventional energy sources technologies. The operation of the 300 MW lignite fired power plant of Ptolemais integrated with a solar field of parabolic trough collectors was simulated using TRNSYS software in both power boosting and fuel saving modes. The power plant performance, power output variation, fuel consumption and CO2 emissions were calculated. Furthermore, an economic analysis was carried out for both power boosting and fuel saving modes of operation and optimum solar contribution was estimated. (C) 2013 Elsevier Ltd. All rights reserved.