solar field is reduced and the solar input is penalized. For a real plant, further considerations should be made. The steam turbine power block must be designed to be bigger to account for the increased steam flow rate. However, when the solar radiation is not available, the produced steam mass flow rate is lower and the system runs in off-design condition. Thus, the efficiency and the power output of the Rankine cycle power block reduces. In order to provide the same thermal input to this section of the plant, the exhaust gas temperature must increases. However, this event should be avoided because the efficiency of the gas turbine system decreases and the plant results to be unbalanced. Figure 6.5 represents the monthly average solar share for the two systems. Solar related evaluation metrics results SHCC ISCC 0.36 0.09 0.02 -0.83 0.20 0.15 874.10 -828.62 10111.54 1814.97 Figure : Monthly average solar share The annual average net incremental solar efficiency of the ISCC plant calculated respect to a high efficiency combined cycle power plant is negative. This means that the reference plant would have produced more power assuming the same fuel consumption of the Integrated solar combined cycle. Note that the solar input in the steam cycle increases the power output of this section, but it does not affect the fuel consumption. The increase in the electrical power is not compensated by a reduction in the fuel consumption, leading to a negative value for the net incremental solar efficiency. Figure 6.6 report the monthly trend for this variable. The of the SHCC plant is always higher than respect to the ISCC system. The parameter refers to the net incremental solar efficiency calculated assuming the reference efficiency to be 50.29 %. This value is the electrical efficiency of the ISCC system when the DNI is zero. In other words, the reference plant is considered to be a combined cycle power plant similar to the
solar field is reduced and the solar input is penalized. For a real plant, further considerations should be made. The steam turbine power block must be designed to be bigger to account for the increased steam flow rate. However, when the solar radiation is not available, the produced steam mass flow rate is lower and the system runs in off-design condition. Thus, the efficiency and the power output of the Rankine cycle power block reduces. In order to provide the same thermal input to this section of the plant, the exhaust gas temperature must increases. However, this event should be avoided because the efficiency of the gas turbine system decreases and the plant results to be unbalanced. Figure 6.5 represents the monthly average solar share for the two systems. Solar related evaluation metrics results SHCC ISCC 0.36 0.09 0.02 -0.83 0.20 0.15 874.10 -828.62 10111.54 1814.97 Figure : Monthly average solar share The annual average net incremental solar efficiency of the ISCC plant calculated respect to a high efficiency combined cycle power plant is negative. This means that the reference plant would have produced more power assuming the same fuel consumption of the Integrated solar combined cycle. Note that the solar input in the steam cycle increases the power output of this section, but it does not affect the fuel consumption. The increase in the electrical power is not compensated by a reduction in the fuel consumption, leading to a negative value for the net incremental solar efficiency. Figure 6.6 report the monthly trend for this variable. The of the SHCC plant is always higher than respect to the ISCC system. The parameter refers to the net incremental solar efficiency calculated assuming the reference efficiency to be 50.29 %. This value is the electrical efficiency of the ISCC system when the DNI is zero. In other words, the reference plant is considered to be a combined cycle power plant similar to the