Given the current influx of intermittent renewable energy sources due to the German Energiewende, additional flexibility is needed to guarantee a reliable power supply by varying electricity generation. Battery energy storage systems are playing an important role for the grid stabilization in Germany. This paper analyses the hybrid concept of combining batteries with power-to-heat technology in the environment of primary control reserve. A comparative economic assessment of hybrid and stand-alone battery systems is discussed by making use of a simulation model in MATLAB". The economic feasibility of a sustainable business model was investigated in accordance with the German regulatory framework. By comparing to a stand-alone battery system providing primary control reserve, simulation results revealed that the combination with a power-to-heat system is another option for providing a reliable frequency regulation. Despite the additional cost of power-to-heat units, grid fees, taxes and expected shorter lifetime of the battery cells, the hybrid solution leads to an improved profitability scenario for investors when compared with a stand-alone battery in a PCR market.