  The integration of large shares of electricity produced by non-dispatchable
Renewable Energy Sources (RES) leads to an increasingly volatile energy
generation side, with temporary local overproduction. The application of energy
storage units has the potential to use this excess electricity from RES
efficiently and to prevent curtailment. The objective of this work is to
calculate cost-optimal charging strategies for energy storage units used as
buffers. For this purpose, a new mathematical optimization method is presented
that is applicable to general storage-related problems. Due to a tremendous
gain in efficiency of this method compared with standard solvers and proven
optimality, calculations of complex problems as well as a high-resolution
sensitivity analysis of multiple system combinations are feasible within a very
short time. As an example technology, Power-to-Heat converters used in
combination with thermal storage units are investigated in detail and optimal
system configurations, including storage units with and without energy losses,
are calculated and evaluated. The benefits of a problem-specific approach are
demonstrated by the mathematical simplicity of our approach as well as the
general applicability of the proposed method.
