Decentralized energy supply is a frequently discussed topic in German industry, caused by continuously rising energy prices. This study assesses configurations of hybrid renewable energy systems (HRES) with regard to their ability to decrease a company's energy supply costs. We apply mixed-integer linear programming (MILP) to optimize an electricity and heat supply system with the aim of minimizing annual costs and perform energy system optimizations for a sample of three case studies and 363 virtual companies. Our results show that systems consisting of grid supply, combined heat and power plants (CHP), heat storage facilities and, in some cases, photovoltaics can lower the sample companies' annual energy costs by an average of 8.3%, including annualized investments. For a time frame of 20 years, the average internal return rate of the HRES investments is 29.8%. This work expands the body of literature on HRES optimizations by shifting the research focus from household to industrial supply. Our model can support corporate investment decisions on decentralized supply facilities. (C) 2017 Published by Elsevier Ltd.