Evaluation criteria for enhanced solar–coal hybrid power plant performance

• New criteria to evaluate the solar hybrid power plant were developed.
• Typical solar–coal hybrid power plants were evaluated using the criteria.
• The integration principle of solar–coal hybrid systems was determined.
• The benefits of the solar–coal hybrid system are enhanced at lower solar radiation.

Attention has been directed toward hybridizing solar energy with fossil power plants since the 1990s to improve reliability and efficiency. Appropriate evaluation criteria were important in the design and optimization of solar–fossil hybrid systems. Two new criteria to evaluate the improved thermodynamic performances in a solar hybrid power plant were developed in this study. Correlations determined the main factors influencing the improved thermodynamic performances. The proposed criteria can be used to effectively integrate solar–coal hybridization systems. Typical 100 MW–1000 MW coal-fired power plants hybridized with solar heat at approximately 300 °C, which was used to preheat the feed water before entering the boiler, were evaluated using the criteria. The integration principle of solar–coal hybrid systems was also determined. The proposed evaluation criteria may be simple and reasonable for solar–coal hybrid systems with multi-energy input, thus directing system performance enhancement.