Optimum community energy storage system for PV energy time-shift

A novel method has been designed to obtain the optimum community energy storage (CES) systems for end user applications. The method evaluates the optimum performance (including the round trip efficiency and annual discharge), levelised cost (LCOES), the internal rate of return and the levelised value of suitable energy storage technologies. A complimentary methodology was developed including three reference years (2012, 2020 and zero carbon year) to show the evolution of the business case during the low carbon transition. The method follows a community approach and the optimum CES system was calculated as a function of the size of the community. In this work, this method was put in practice with lead-acid (PbA) and lithium-ion battery (Li-ion) technologies when performing PV energy time-shift using real demand data from a single home to a 100-home community. The community approach reduced the LCOES down to 0.30 £/kW h and 0.11 £/kW h in 2020 and the zero carbon year respectively. These values meant a cost reduction by 37% and 66% regarding a single home. Results demonstrated that PbA batteries needs from 1.5 to 2.5 times more capacity than Li-ion chemistry to reduce the LCOES, the worst case scenario being for the smallest communities, because the more spiky demand profile required proportionately larger PbA battery capacities.