The use of fossil fuels should be reduced in near future due to their limited resources and increasing ecological impacts. Therefore, increased interest and incentives have been created for development of electricity supply utilizing renewable energy such solar energy, which has long-range potential and is applicable in most geographical regions. This paper describes the methodology used to study solar supported steam generation in combined cycle power plants. The existing algorithms for unit commitment and production simulation were modified and extended to account for the mode of operation of these solar supported plants. Moreover, the economic impact of solar energy is assessed in the form of cost/benefit ratio to justify the substitution potential of such clean energy. The feasibility of solar energy substitution is illustrated using the planned 2 x 130 MW solar supported plant in Kuraymat, which would be integrated to the Egyptian unified power network. (c) 2004 Elsevier Ltd. All rights reserved.