The Effective Energy Shift (EfES) algorithm: A non-iterative piece-wise linear method for mapping storage capacity to self-sufficiency and self-consumption

The Renewable Energy Sources wind and solar are key drivers for the transition to a greenhouse gas neutral economy. However, they pose the inherent problem of high fluctuation in their availability, thereby affecting the consistency of energy generation. Energy Storage System (ESS) are a key technology for solving many of the emerging challenges. As these entail their own investment costs, the added benefit of these systems has to be calculated. Typical energetic measures are self-sufficiency, self-consumption and the loss-of-load probability. The considered energy system possesses some form of renewable energy generation, an intrinsic energy demand and a potential ESS. This paper presents a deterministic efficient algorithm that uses time series for the demand and renewable generation to construct an exact mapping by a closed-form expression and its parameters for the named energetic measures as a function of the usable capacity of the ESS. To enable these closed-form mappings we introduce the effectiveness of the storage, a precise, loss-agnostic operational/usage metric that generalizes the familiar equivalent full cycles (EFC). For comparability, we report both the internal EFC and the delivered EFC. This clarifies where discharge losses are applied and resolves inconsistent “cycle count” conventions in the literature. Power limits, charging and discharging efficiencies, and efficiencies for the direct use of generation by the system can be considered. Since no simulation or optimization is required to perform the analysis, it is computationally efficient and easy to set up with a relatively small amount of input data.