Solar aided (coal-fired) power generation (SAPG) which is an efficient way to integrate solar thermal energy into normal coal fired power generation can reduce standard coal consumption rate (SCCR) for the coal fired power station and enhance solar-to-electricity efficiency (SEE) compared with solar alone thermal power generation. A SAPG model has been developed to study the energy and economic benefits of the SAPG system with different capacities, in this study. The benefits are analyzed and discussed based on 5 criteria i.e. SEE, solar power generation (SPG), saved SCCR, annual SEE and levelized cost of energy (LCOE). The results show that the SAPG benefits are linked with the capacity of coal power plant and the collector areas installed. The results of a case study show a general trend that SEE, SPG and saved SCCR all peaked at designed aperture areas of solar field, but LCOE and annual SEE are optimum at a larger than designed collector areas. The results also show the saved SCCR is greater in smaller plants while the annual SEE is higher in larger plants. Therefore, for different solar field aperture area and capacity of units, optimization integrated scenario is different based on different criteria. (C) 2017 Published by Elsevier Ltd.