In dry regions with abundant solar radiation at Southern latitudes between 30 and 40 degrees, such as the central-western part of Argentina, it is possible to obtain domestic hot water by means of simple integral collector accumulator systems, which are less expensive than the classical flat plate active systems. The experimental assessment of two solar accumulator collector systems yielding 300 l of hot water daily is reported in this work. Daily diurnal global efficiency and nocturnal thermal losses have been systematically determined over a 5-month period, from austral summer to austral winter. The results of these systems were compared with the results obtained from a high quality thermosyphon solar system composed of a flat plate collector and its corresponding insulated storage tank. tested at the same time. The experiments were carried out by measuring the climatic variables, temperatures in different parts of the collectors, and mass flow rates of water. during the test days. Based on these measurements, the behaviour of the systems was analysed by comparing exit temperatures, heat losses, and delivered useful energy. An economic evaluation was made considering the investment time recovery through the savings the system could provide working with different conventional sources, of energy. The systems proved to work efficiently, although some improvements should be made on the se mi transparent thermal insulation in order to enhance its winter performance.