The paper presents selected results of industrial research and development work related to the implementation of a research project aimed at determining the technology for optimum cooperation of a CHP plant with a highly efficient heat storage system. As part of the first phase of the project, the static and dynamic properties of key elements of the CHP technological system were determined and, based on them, concepts were proposed for improving the economic efficiency of combined heat and power (CHP) generation through the active use of the heat accumulation phenomenon. The article presents selected results of this work. These are the initial assumptions related to the selection of the heat accumulator capacity taking into account the operation in the daily cycle in order to maximise the production of electricity at hours with the highest sale price. Variability of electricity sale prices during a day recorded at the Polish Power Exchange is presented. A methodology for preliminary determination of proper heat accumulator capacity was presented.