A Methodology for Determining Optimum Solar Tower Plant Configurations and Operating Strategies to Maximize Profits Based on Hourly Electricity Market Prices and Tariffs

The present study analyses the influence that market conditions have on determining optimum molten salt solar tower plants with storage that maximize profits (in terms of plant configuration, sizing and operation) for a location in South Africa. Three different scenarios based on incentive programs and local wholesale electricity prices are considered. A multi-objective optimization modeling approach was followed, showing the trade-off curves between minimizing investment and maximizing profits when varying critical sizerelated parameters (such as nameplate capacity, solar multiple and storage capacity) together with power-cycle design and operating specifications including dynamic start-up curves and different storage dispatchability strategies. Results are shown by means of a comparative analysis between optimal plants found for each scenario, highlighting the value that storage has under the current two-tier tariff scheme, and the relevance of designing a suitable policy for technology development. Lastly, a final analysis is performed with regards of the indicators used for economic evaluation of power plants, by comparing the differences between optimum designs found when using the levelized cost of electricity solely as performance indicator instead of cash-flows and profit-based indicators, such as the internal rate of return.