The effect of the Proca photon mass m(ph) and cosmic vector potential A(C) on the dynamics of solar wind is considered. For large-enough values of the parameter A(C)m(ph)(2), the solar wind structure at a distance of approximately 40 AU from the Sun should change significantly with respect to the actual observed flow. The absence of such deviations gives an upper bound on the parameter A(C)m(ph)(2) 9 orders of magnitude less than in laboratory experiments measuring torque on a toroidal magnet.