Solar irradiation measurements in Jordan and comparisons with Californian and Alpine data

Abstract

In order to obtain reliable irradiation data for the design, operation and economic assessment of solar power stations, a measurement campaign has been performed in Jordan. As promising sites the desert near Quwairah in the South of Jordan, the stony desert South East of Amman and the elevated plateau near Naqb and also in the South of Jordan were chosen. Measurements were performed during the period of June 1989 to July 1992. The data were evaluated and compared with data of Barstow, California and the Swiss Alps. From the yearly sums of the direct normal irradiation in 1990 and 1991 at Quwairah (2701 and 2436 kWh/m2 respectively) it is concluded that this site is comparably as good for solar thermal power stations as the Barstow site. The global normal irradiation (usable with sun-tracked photovoltaic panels) had the surprisingly high values of 3551 and 3373 kWh/m2 in 1990 and 1991 respectively. Occasionally peak values of the global normal irradiation greater than the solar constant were measured (up to 1500 W/m2). Missing global normal data from other arid sites do not permit comparison. As known before, the corresponding values in the Swiss Alps are considerably lower (1100-1700 kWh/m2 for the direct normal irradiation and 2000-2500 kWh/m2 for the global normal irradiation respectively, depending on the year and site). In addition to the direct normal and global normal irradiation, the global horizontal and global inclined (30° South) irradiation were measured, amounting to 2353 and 2499 kWh/m2 respectively in 1990. Data have also been collected on wind, rainfall, ambient temperature, dew point and surface pressure. All data are available in a computer accessible form, in particular as a yearly set of 5 min mean values of the direct normal irradiation for 1990. Combining the ground measured data with METEOSAT-data resulted in a unique map of the direct normal irradiation for Jordan and surrounding countries, indicating attractive sites for solar power stations. The measurement campaign was made possible by active support from the Ministry of Energy and Mineral Resources, MEMR and the Jordan Electricity Authority, JEA, both at Amman, as well as by generous financial support of the Swiss Committee for Scientific Research, KWF, Berne.