Recent advances in solar resource assessment in Uruguay

In the last few years, considerable effort has been invested by the Uruguayan government to increase the amount of renewable energies in its energy matrix. Research and development aiming at introducing solar energy at large scale has been initiated only recently. A ground measurement network for solar irradiation deployed by Facultad de Ingeniería, Universidad de la República, started to operate in 2009, and new measurement sites have been continuously added since then. A first characterization of the solar resource was made in 2009, based only on ground data. More recently, in 2011, a pre-existing statistical satellite-based model proposed by Justus, Paris and Tarpley (JPT) has been implemented and adjusted to the Uruguayan territory. An improved version of the model has then been proposed and implemented. These models are built by integrating data from ground measurement networks with satellite data captured by GOES-East satellites. In this paper we describe the current state of the solar measurement network administrated by Facultad de Ingeniería, as well as other networks of ground stations deployed over the country. We also discuss two satellite-based irradiation models that have been and are being used for solar resource assessment in Uruguay. Performance evaluation and comparison of both models is presented. In particular, we show that a simple modification of the JPT model, that explicitly introduces brightness dependence in the model parameters, significantly improves the estimation accuracy, and allows to achieve uncertainties as low as 13.7% and 6.8% at hourly and daily time basis, respectively.