The main target of this paper is to determine the seasonal features of the wind speed inthe northwestern of Senegal and to assess the cost of annual energy output using windturbines provided from several manufactures. The wind data used for this study werecollected in four sites located in the northwestern coast of Senegal and cover the periodof one year. The seasonal mean wind speed and the annual distribution curves were obtainedby using the Weibull distribution function. A technical assessment of electricitygeneration from five big wind turbines which power is between 640 kW and 2000 kW and fromsix small wind turbines which power is between 250 W and 10 kW were carried out. Theresults obtained show that the lower cost (0.0265 €/kWh in Sokhar) was observed for thewind turbine Ecotècnia 62. The highest cost was 0.5103 €/kWh (in Gandon) observed for thetechnology of Alize. All wind turbines was better suited to the site of Sokhar with thehighest capacity factor and the lowest cost of output energy.