This work aims to facilitate higher photovoltaic (PV) penetration in distribution networks, by utilising an energy storage system (ESS) and the on-load tap-changer (OLTC) mechanism at the substation transformer. The dispatch commands to the ESS are generated by a new droop characteristic, that relates the ESS active power to the power surplus. The identification of the appropriate droop characteristic is assigned to the scheduling algorithm that generates dispatch commands both for the ESS and the OLTC. First, the ESS is dispatched alone, and then, a joint dispatch is performed combining the ESS and the OLTC. For each of the above dispatch strategies, the lowest cost solution for ESS placement and sizing (kW, kWh) is identified, and possible differences are discussed. To demonstrate the effectiveness of the proposed droop characteristic, simulation results for a real-life distribution network in Queensland are presented.