Innovative Energy Systems Act of 2013 - Amends the Internal Revenue Code to allow an energy tax credit for highly efficient combined heat and power system property. Defines such property as property at an industrial, commercial, or institutional facility comprising a system that is placed in service before January 1, 2017, and that: (1) uses the same energy source for the simultaneous or sequential generation of electrical power, mechanical shaft power, or both, in combination with the generation of steam or other forms of useful thermal energy; and (2) has a system design that provides an energy efficiency percentage of at least 70%.