Viability of a concentrating solar power forecasting system for participation in the Spanish electricity market

The Spanish energy legislation allows renewable energy producers to participate in the liberalized electricity market. Day-ahead market participation requires a power production forecast for the following day in hourly resolution, to be announced to the market operator before 10 a.m. For a concentrated solar power (CSP) plant, this means that a site-specific weather forecast for 38 hours has to be available, based on which electricity production is calculated by means of a power plant model. Since deviations from the production schedule may lead to deviation penalties, an important issue for production forecasting is the accuracy of direct normal irradiance (DNI) forecasts as one of the main input parameters. The European Space Agency (ESA) co-funded research project CSP-FoSyS aims at developing such an electricity production forecasting tool for the 50 MWel parabolic trough plant Andasol 3. This paper elaborates its economic viability by assessing a DNI forecast made available for the period 2007 to 2009. Commercially available DNI forecasts available today can mitigate penalty charges by about 40%, compared to the obvious alternative of persistence forecasting, i.e. assuming yesterday’s or today’s weather conditions for the following day. The impact of forecast accuracy improvements as well as adapted strategies is also assessed in this paper