Wind profile assessment at Masitise and Sani in Lesotho for potential off-grid electricity generation

Wind profile of two sites, one on the southern part of Lesotho, Masitise (−30.367445° latitude, 27.669641° longitude, 1700 m altitude), and the other on the eastern part, Sani (−29.58273° latitude, 29.287845° longitude, 2900 m altitude), was analysed. Wind speed measurements for Masitise are taken at both 10 m and 25 m above ground level (a.g.l.) while for Sani anemometers are only placed at 9 m a.g.l. Both sites fall under the zero roughness class with bi-annual wind speed of 4.93 m/s and 5.50 m/s at 10 m and 9 m a.g.l., respectively. Moreover, their power densities are given by 121.6 W/m2 and 221.3 W/m2. A model using Weibull distribution function is used to analyse the wind speed profile. The results compare well with the Wind Atlas Analysis and Application Program (WAsP). According to the global wind power classification, Masitise is a class 2 site while the windier site of Sani falls under class 3. Masitise may not be ideal for grid-connected electricity production but both sites have sufficient wind for off-grid electricity production. On average the turbines will be generating 80% and 75% of the time per annum at Masitise and Sani, respectively.