Using the global solar radiation on a Bat plate converter of selective surface, the process temperature, the ambient temperature and the characteristics of the collector as initial data; the maximum available exergy for feeding a lithium bromide absorption cooling machine and its daily distribution in Madrid is determined. The conversion of solar radiation into exergy is calculated through the Muser endoreversible engine. The model, which takes into account the relative Sun-Earth movements, the presence of the atmosphere, the transitory regime, the losses to the surroundings and the losses caused by the heat capacities effect, allows a maximum hourly exergy efficiency of the available heat between 11 and 14.6% and a daily exergy efficiency in the order of 3% to be obtained. The maximum available daily exergy varies from 800 kJ/(m(2) day) for a very hot clear day to 950 kJ/(m(2) day) for a warm clear day.