The electric vehicles can contribute to reducing electricity costs by providing their batteries as temporary energy storages. The paper presents a new mechanism of their implementation in systems with distributed energy resources. The method is based on individual contracts that facility company makes with the drivers of electric vehicles. The company that has own energy generation from photovoltaic panels, stores and uses the electricity in the batteries of vehicles while they are in the parking lot. The contracts specify the required level of charge at the end of agreement and the financial compensation. The paper analysed proposed cooperation between facility owner and multiple electric vehicles in simulation, using real energy, weather and vehicles behaviour data. All the electric vehicles can significantly reduce the average recharging bill, as well as the facility owner gets lower electricity expenses.