In this paper, a method is derived for evaluating the thermo-economic performance of solar aided power generation (SAPG) hybrid systems. These systems can achieve emissions reduction and energy savings compared to conventional coal-fired power generation systems. In the discussed model of SAPG hybrid system, various stages of heating feed-water in a conventional coal-fired power plant steam Rankine system are replaced by steam injected from solar direct steam generation (DSG). In order to determine the thermo-economic viability of SAPG compared to conventional power generation, convenient methods are required for evaluating the performance of SAPG systems. Therefore, an analysis method is developed which involves defining a generalized steam-water distribution matrix equation. This matrix approach simplifies the traditional thermal calculation and has a one-to-one correspondence with the system structure. As a case study, the proposed method is successfully used to solve the case of a 600 MW power generation system with the integration of DSG. A comparison of the case study system with (SAPG) and without (non-SAPG) the integration of the solar DSG shows thermo-economic benefits to the hybridised system. If the state parameters are taken as variables, this method can be used to study the effects of changes in system, equipment, operation, and load on the thermal economy of the integrated system. (C) 2016 Elsevier Ltd. All rights reserved.