This paper shows the relationship between the incident solar radiation and the optimum outlet temperature of a solar field to produce the highest amount of electrical power. Various simulations were made for different values of incident solar radiation, calculating for each one the optimum temperature which produces the maximum electrical power and demonstrating that to operate the field at the highest allowable temperature is not the optimal operating point from certain values of solar radiation; a situation which takes special relevance during cloudy days. These simulations were carried out using two connected models, one for the solar field and another one for the power cycle.