Comparison of Different Solar to Electric Power Options for 24 Hours Continuous Power Supply

Abstract

Abstract Solar energy utilization, including both photovoltaic and thermal solar energy generation methods, faces the challenges of intermittency and energy curtailment on the electric grid. To achieve a consistent 24/7 electric power supply, exploring options for storing daylight solar energy surplus for the period without solar irradiance is essential. The popular approaches include combinations of photovoltaic modules and batteries, and solar thermal power plants implemented with molten salt. However, there are many other options, each with unique pros and cons. Comparisons of those options have been scattered in different publications and are not always based on the same conditions or the efficiency definition. The objective of this study is to place 18 different scenarios under the same conditions and investigate their overall solar-to-electricity efficiencies for a typical 24-hour period. The energy storage options include battery, pumped heat, pumped hydropower, compressed air, flywheel, potential energy, molten salt, falling particles, and H2 generation by water-electrolysis, photo-electrochemical, and thermo-chemical conversions. Moreover, thermal solar power plants with different heat transfer mediums, energy storage options, and power blocks of Rankine, sCO2, and Helium Brayton cycles, as well as sCO2-Isopentane and Air-ORC combined cycles, were analyzed. The efficiency benchmark ranking revealed that the top three thermal solar combinations significantly outperform all photovoltaic scenarios, while photovoltaic green hydrogen scenarios perform much better than the thermochemical configuration. Furthermore, the benchmark indicated that gravity potential and pumped heat are valid energy storage options that operate very close to batteries in photovoltaic scenarios.