Due to the intermittent nature of solar power, it cannot be used as a capacity based generation resource throughout the entire day. In order to achieve high levels of penetration into the electric gird, solar power will require coupling with some form of energy storage. A systems level model is used to assess the technologic and economic benefits of adding battery energy storage to a solar array in order to meet specific, local demand needs. Real world sites are analyzed using solar irradiance data from NREL’s Measurement and Instrumentation Data Center1.
The systems level model includes components for a solar array, battery storage, controls for power flow and allows for inputs of real-world solar irradiance data and site demand. The battery component uses a physics based model including electrochemical and transport principles to model intercalation based battery systems2. Systems for dispatching power between the solar array, battery, and grid are included and power flow is determined based on real-time available solar power and grid demand3. Physics-based capacity fade mechanisms are included in the battery model to assess the amount of degradation caused by different types of irradiance and demand patterns4.
Assessment of the solar+battery system will include measures of site autonomy, battery utilization, and solar energy utilization. In addition to an analysis of the technologic benefits, a study of economic value gained by systems under a time-of-use (TOU) utility price structure will be included based on the operational output of the model. While autonomy increases with the addition of battery storage the value of battery capacity added varies based on both the demand and available solar energy. The economic value under TOU pricing will be heavily dependent on both the on-peak price of energy and the nominal cycle life of the battery. These model-based studies are important for quantifying the benefit of adding energy storage to specific renewable generation.
The authors acknowledge financial support from the U.S. Department of Energy’s Advanced Research Projects Agency- Energy (ARPA-E), and the Solar Energy Research Institute in India and the United States (SERIIUS), as well as, Washington University in St. Louis’ McDonnell Academy Global Energy and Environmental Partnership (MAGEEP).
1. National Renewable Energy Laboratory. (2014, 2014). Measurement and Instrumentation Data Center (NREL). Available: http://www.nrel.gov/midc/
2. S. Santhanagopalan, Q. Z. Guo, P. Ramadass, and R. E. White, Journal of Power Sources, 156, 620(2006)
3. M. T. Lawder, V. Viswanathan, and V. R. Subramanian, Journal of Power Sources, 279, (2015)
4. M. Safari, M. Morcrette, A. Teyssot, and C. Delacourt, Journal of the Electrochemical Society, 156, A145(2009)
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