Time-varying export tariffs can play a key role in integrating renewable energies and improving grid utilization. This is shown by Lisa Restel, co-author of a new study that analyzes the influence of such tariffs on the load profiles of households in Melbourne. 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 kWP PV and 12 kWh battery, and a dispatch optimisation model.
This research is particularly relevant considering Australia’s pioneering role in the expansion of household solar photovoltaics (PV). Although this strong growth has helped to accelerate the energy transition, it has also changed demand such that the power system faces operational challenges, known as the “solar duck curve” (high feed-in of solar energy at midday and a steep increase in demand in the evening hours). The growing adoption of household batteries will change demand once again and policymakers have the means to reshape this demand through time-varying tariffs.
The study shows that 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. However, it is found 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.
“Our research shows that time-varying export tariffs have a significantly greater influence on residual load profiles than time-varying import tariffs,” explains Lisa Restel. “This makes them a potentially effective lever for policy measures to promote the integration of solar energy and better align economic incentives for households with the realities of the wholesale electricity market.”
The findings are especially relevant for policymakers and electricity providers, as they offer actionable insights into how household net-load can be strategically influenced through time-varying tariffs.
The full article entitled “Counteracting the duck curve: Prosumage with time-varying import and export electricity tariffs” was recently published in Energy Policy and is freely available at https://doi.org/10.1016/j.enpol.2024.114461. Co-author of the publication is Dr. Kelvin Say, postdoctoral researcher at the University of Melbourne.
