Fast reaction times and high discharge rates make steam accumulators a promising option for compensation of fast transients in insolation for solarthermal systems using steam as working medium. Using the volume of components like separator drums or heat exchangers for storage of pressurized hot water is a cost-effective approach to integrate buffer storage capacity. While the basic steam accumulator shows a decline in pressure during the discharge process, there are also concepts maintaining constant pressure. The integration of latent heat storage material allows an increase in volumetric storage capacity. The availability of steam accumulators for compensation of fast transients also helps to reduce the requirements concerning reaction time and discharge rate for storage systems intended for supplying stored energy over longer periods. (c) 2005 Elsevier Ltd. All rights reserved.