igure 4. Variation of DNI Figure 5. Solar Field output
As shown in Fig. 6(a), the additional steam mass flow generated by HSSG varies as it depends on solar radiation to reach a maximum of 65 kg/s when DNI gets at maximum. As a result, the total SPT output (Fig. 6(b)) is equal to 62 MW compared to that at night equal to 35 MW, which means an increase in electricity production about 27 MW. Fig. 6(c) gives an idea about the power plant output during the 21st of March (design point) at the specified site conditions. During the nights or cloudy periods ISCC operates as CC and produces about 129 MW and its thermal efficiency reaches 52 %, according to Fig. 6(d), while during the day, the net electricity production is increased to 156 MW and the thermal efficiency reach its highest value of 63 % at midday. The estimated solar electricity ratio ( Fig. 6(e)) based on the difference in electrical output of ISSC mode and CC mode varies from sunrise to sunset according with solar radiation to reach a maximum of 17 % at midday.