Impact of the intra-day variability of the DNI on the energy yield of CSP plants

Abstract

The operation and the electricity yield of CSP plants in two days with the same daily-accumulated DNI, even with the same Aperture Normal Irradiance (ANI) can be very different depending on other parameters such as the variability and distribution of the solar radiation. In this paper, we intend to quantify the impact of the intra-daily variability of the DNI on the production of CSP plants. To that end, we use the ND model [1] to generate several synthetic years with similar distribution and daily energy to a reference measured year but different levels of intra-daily variability. We use System Advisor Model (SAM, https://sam.nrel.gov/) to simulate the performance of two parabolic trough (PT) plants, with and without thermal storage and common configurations for the location of Seville, Spain. To test the influence of the DNI variability, we simulate the measured and the synthetic years and we compare the daily gross power produced. As result, a clear decrease in the gross production of the PT plant without TES system is observed when the intra-daily variability increases, with daily average differences of 47% respect to the case with lowest variability. This difference is reduced with the use of the TES system to 6 %, damping the dynamic effects of the DNI variability on the global response of the plant.