Solar climate of Azores: results of monitoring at Faial and Terceira islands

The North Atlantic archipelago of Azores (Portugal) consists of nine islands, located about 1,500 km from mainland Europe. Currently the Azores has about 243,000 inhabitants, which depend heavily on imported fossil fuel for their energy supply. This is a concern for the regional Government and its Agency for Energy and Environment, ARENA, which naturally support energy efficiency and use of renewable energies. The Azores are rich in several renewable resources, and have even pioneered Portuguese exploitation of wind, wave, and high enthalpy geothermal energy for electricity generation. However, so far solar energy has not been a priority in the renewable energy panorama, probably because the Azores climate has been considered too cloudy. Nevertheless, this is true only in comparison with the Portuguese mainland, as the radiation levels are probably similar or even better than those of Northern Europe. In this context ARENA is developing efforts for increasing the use of solar systems. A collaboration, partly financed by an INTERREG III B Project of the European Community, has been established with INETI, the Portuguese Public Laboratory for the area of Energy, to improve the solar climatology of the Azores. This climatology is indeed quite incomplete. It consists mainly on daily measurements for two sites only at the S. Miguel and Terceira islands. Some sunshine records are available from Campbell-Stokes heliographs. Satellite data exists but their quality is uncertain due to the small size of the islands and the shallow view angle