Fig. 5-15. Optimization Model, Photovoltaic SPS The "objective function" is dependent variable one (1) "Total Power Generation Cost Per kWe." The machine program to process this model is ISAIAH (Integrated Sensitivity and Interactions Analysis- Heuristic). As an example of the form of the data used in this model, refer back to Figure 4-31. This is the cost of solar arrays (per unit area) relative to the total area of cells procured. A production rate factor (or learning curve) of 80% was used; when the quality (area) produced is double that of the previous quantity, the unit cost per area of that quantity is 80% of that unit cost per area of the previous quantity. The curve of Figure 4-31 was used to produce Table #7 "CELL ARRAY COST/M2" in Figure 5-15. Asa further example, Figure 4-30 was the basis for Table #18 "CELL EFFICIENCY, EFFECTIVE, WITH RADIATION." Figure 5-16 shows the optimization results. Minimum orbit busbar costs are obtained with silicon solar cells with a concentration ratio of approximately 4.3. This means that the projected Fig. 5-16. Derivation at Optimum Concentration Ratios area of the SPS would be 4.3 times the area of the cells. The resultant SPS is not a minimum mass system. As shown in Figure 5-17, minimum cost does not coincide with minimum mass. The assumed transportation cost to geosynchronous orbit in this optimization was $80 kg ($36.3/lbm). In general, if solar cell costs for an SPS program are
RkJQdWJsaXNoZXIy MTU5NjU0Mg==