The present article presents the development of compressed wind speed data to be used in wind energy and performance calculations of stand alone or hybrid wind energy systems. Compressed data attempts to represent the important statistics of an entire month of days with d selected days, where d is less than the actual number of days in the month. In the present article, compressed wind speed data are generated based on the Weibull wind speed distribution model. Two different sets of wind speed data are generated, three- and four-day month, each month being represented by 72 and 96 h of wind speed, respectively. The three- and four-day month wind speed data are then used to calculate the monthly energy yields, which, in turn, are compared to those calculated from the measured hourly time series data. A total of eight years long of measured hourly time series data from five different locations throughout the world are used to validate the method presented. The overall errors in estimation of the wind energy yield using the Weibull representative compressed wind speed data are 3.67% and 3.21% for the three- and four-day months, respectively. (C) 2003 Elsevier Ltd. All rights reserved.