Counteracting the duck curve: Prosumage with time-varying import and export electricity tariffs

Australia is a frontrunner in household solar photovoltaic (PV) adoption, which has helped to accelerate the energy transition but has changed demand such that the power system faces operational challenges, known as the solar ‘duck curve’. The growing adoption of household batteries will change demand once again and policymakers have the means to reshape this demand through time-varying tariffs. This study evaluates the impact of time-varying import and export tariffs on household load profiles using data from 400 Melbourne households, each equipped with a 9 kW P PV and 12 kWh battery, and a dispatch optimisation model. Our findings indicate that time-varying export tariffs have significantly more influence on residual load profiles compared to time-varying import tariffs. With time-varying import tariffs only, households still maintain grid feed-in during the day and rely on self-consumption in the evening, exacerbating midday feed-in but preventing peak demand growth. We find that time-varying export tariffs alone reduce midday feed-in by 55.6% and extend exports past sunset. This actively counteracts the ‘duck curve’ by reducing midday feed-in and decreasing peak evening operational demand. This suggests that time-varying export tariffs may be a useful policy lever to enhance grid utilisation and renewable energy integration. • MILP modelling of Time-of-Use (ToU) and -Export (ToE) tariffs on PV-BESS households. • ToU are less effective than ToE tariffs and may be regressive for low-income groups. • ToE tariffs reduce midday feed-in and lower system peak demand via BESS discharge. • ToE tariffs counteract the duck curve by shifting feed-in and reducing peak demand.