Many attempts have been made to use solar energy in absorption refrigeration systems. In all these systems an important component is the regenerator, in which the weak solution is reconcentrated. Among the regenerators found in the literature, open regenerators have received much attention because of their simplicity. However, problems with solution contamination, and low performance under humid climates have pointed towards alternative regenerators. It has been shown that covering the regenerator with glass solves these problems permanently. Still, an analysis of the energy and mass transfer processes occurring inside the regenerator has not been fully presented. In this paper, a one-dimensional theoretical simulation of a closed solar regenerator is developed. The theoretical model is constructed by combining three energy balances and three mass balances on infinitesimally thin slices of the solar regenerator, the solution, and the solution-vapor interface. These balances yield three independent ordinary differential equations in the three dependent variables: solution temperature, glass (condensed water) temperature and solution mass flow rate. Solutions to the differential equations have been obtained numerically and the performance of a typical aqueous solution is presented.