One of the most important problems in the operation of solar power towers is to achieve a uniform flux density distribution at the receiver in order to avoid hot spots. The problem can be solved by computing the aim points of the heliostats by optimizing a function which measures the uniformity of the flux density over the receiver. Due to the high number of heliostats of current commercial plants (more than 900), the number of decision variables (1800) makes the centralized approach very difficult to be implemented in real time. In this paper, a distributed optimization algorithm that computes the aim points for the heliostat field to obtain a uniform flux density distribution and maximize the solar irradiation collected by the receiver is presented. The algorithm is tested using a model of the heliostat field of the CESA-1 solar tower plant at the Plataforma Solar de Almeria (PSA) in southern Spain. Simulation results show that substantial reduction of the computational time is achieved while similar performance to that obtained with the centralized approach is attained.