Impact of DNI nowcasting on annual revenues of CSP plants for a time of delivery based feed in tariff

The impact of combined direct normal irradiation nowcasts on revenues of two different concentrating solar power plant technologies under a time-of-delivery tariff is investigated. The applied tariff scheme offers considerably increased remuneration during evening hours with maximum energy demand and is similar to that used in South Africa for some concentrating solar power (CSP) plants already. The ideal forecast derived from ground-based observations was used to quantify the maximum economic advantage of using any forecasting scheme - and is estimated around 4 % for parabolic trough power plants and as around 8 % for solar tower power plants. This implies a maximum impact of up to 2.2 Mio and 5.3 Mio EUR of additional revenues per year for a typical 110 MW solar trough or solar tower power plant, respectively. The investigated nowcast strategy merges several satellite and numerical weather prediction based nowcasts together with a smart persistence approach in order to generate a best-of nowcast for now- and forecast time horizons up to 9 hours and in the 15 min temporal resolution required for the electricity market participation. The results for the combined nowcast are evaluated with respect to daily power plant operating principles and focusing on a power plant specifi forecast verificati n strategy. The combined nowcast is therefore compared with ECMWF IFS based forecasts and with an optimized ground observation driven persistence approach in two representative locations around the Mediterranean area. The study investigates the impact both with respect to annual energy yield and economic annual revenues of CSP plants. It is found that in our study period 2010 and 2013 to 2015 the merged nowcast strategy adds 0.8 to 4.4 % in additional revenues per year compared to the ECMWF IFS day ahead forecast, which is a typical example of nowadays routinely available forecasts in the power plant's control room. This implies additional revenues of about 450 to 2900 kEUR per year when adding a nowcasting scheme to the solar production forecast tool already in operation at some power plants.