TY - JOUR TI - Cost-optimal operation of hybrid heat pump systems with progressive electricity tariffs AU - Stojiljković Mirko AU - Vučković Goran AU - Ignjatović Marko G JN - Thermal Science PY - 2025 VL - 29 IS - 5 SP - 3441 EP - 3452 PT - Article AB - Heat pumps are very significant for wide application of RES and sustainable heating. Their market penetration and extensive application depend on economic performance. Optimization of the operation parameters of energy systems with heat pumps can result in lower costs and higher savings. Heat pumps operate under different electricity pricing structures, which affect the optimization process. This paper presents a methodology for cost-optimal operation optimization of hybrid energy systems with heat pumps that can be used with progressive electricity tariffs and their combination with time-of-use tariffs. It relies on mixed integer linear programming and includes the constraints that handle electricity tariff rules. The paper illustrates an example of the application of this methodology to a heating system with an air-source heat pump and an auxiliary heater. The results show the impact of the energy prices and electricity tariff structures on the operating regimes and the values of the objective function. This approach can enhance the quality of the optimization results and improve the comprehension of cost-optimal operation regimes.