The paper presents thermal and hydraulic analysis of a flat solar collector using CFD-simulation in order to study the influence of the weather conditions (wind velocity) on the collector operation efficiency. Simulation was made with CFD Solidworks Flow Simulation using standard tools of solar radiation simulation and considering the effect of wind. The result obtained is the dependence of the heat carrier temperature difference at the collector inlet and outlet on the operating time for the different values of wind velocity. Modeling the operation of a flat solar collector was carried out under the influence of solar irradiation in the range from 149 W / m2 to 1019 W / m2, which corresponds to the minimum and maximum solar radiant heat flux in the city of Moscow. The impact of the wind in the speed range from 0 to 4 m / s, also most typical for Moscow, was considered. With an increase in the wind speed to 4 meters per second, a drop in temperature drop by 26.46% was recorded relative to calm weather. Under the influence of wind, the heat transfer coefficient averaged over the outer surface of the solar collector varied in the range from 5.172 W / m2 K to 11.571 W / m2 K. The results obtained show that the presence of wind significantly affects the efficiency of converting solar energy into thermal energy, therefore, when choosing a place for installing a solar collector, it is necessary to take into account not only the angle of incidence of solar radiation, but also the wind rose. The stochasticity of the wind potential and solar insolation can be taken into account when designing the structure and installing the SC at a specific object. The above research results allow us to assert an increase in efficiency by 8-12% when performing additional. wind protection measures for flat collectors.