Free afternoon electricity programs are intended to shift household demand to periods of high solar PV generation, reducing midday surplus and evening fossil fuel increases. Research into Australia’s Solar Sharer program suggests such incentives can significantly improve renewable energy use, but results depend on consumer behavior, tax shifting and rebound effects.
Free midday electricity is an important tool to encourage consumers to use appliances and consume more energy during hours of strong photovoltaic production, when electricity supply often exceeds demand, creating inefficiencies in the system. By reducing prices to zero or near zero, consumers are incentivized to shift their energy consumption to these periods, better aligning demand with renewable energy generation and reducing solar energy waste.
With this in mind, a researcher from the University of Cambridge, Ray Galvin, has investigated how the Solar Sharer program – which starts in Australia in July – could pave the way for the introduction of similar incentives in other countries with a high share of renewable energy.
Under this program, households with smart meters receive approximately three hours of free electricity during the day, when there is sufficient solar energy. The time window starts between 11:00 AM and 12:00 PM, depending on the state.
“The plan would be best replicated in markets that have a substantial share of solar energy,” Galvin said pv magazine. “This creates a surge of excess energy around noon and for a few hours either side, when domestic electricity loads are relatively low, but it does not produce in the evening, when most domestic electricity consumption occurs. This results in fossil fuels having to be ramped up in the evening. The Solar Sharer program aims to encourage households to shift some of their load from the evening to the period when solar energy is overproducing.”
Galvin explained that the length of the midday free electricity period should be adjusted to the average amount of excess solar energy, which varies from country to country and season to season within a country. “In Australia, the seasonal difference is not that big, so they can match the period to the average time of excess solar generation,” he added. “For a European country, this would have to be adjusted several times a year. That is why in my research I proposed a communication strategy between electricity suppliers and households, which could optimize the length of free periods and keep households informed.”
In the newspaper “Free Midday Electricity in a Solar Sharer Program: Should Germany Follow Australia’s Lead?” published in Renewable energyGalvin explained that two key behavioral economics factors can determine the effectiveness of free midday electricity schemes: load shifting and rebound effects.
Load shifting refers to the extent to which households shift their electricity consumption from other times of the day to a free afternoon period. In contrast, rebound effects describe the tendency for total electricity consumption to increase when electricity is free or at very low cost, because users may use additional appliances or use energy less sparingly, partially offsetting the system’s intended benefits in efficiency and grid balancing.
Galvin’s analysis shows that Solar Sharer-type schemes can meaningfully increase renewable energy use, but their impact is highly dependent on behavioral responses and system flexibility. The modeling suggests that a Solar Sharer program in Germany could have been viable as early as 2025, provided it successfully shifts electricity consumption from periods of low renewable surplus to times when renewable energy generation exceeds demand.
A moderate rebound effect of around 20% does not significantly reduce the benefits in the model, which assumes that around half of the available excess electricity consumption is shifted to periods of peak demand. Under these conditions, a significant portion of excess renewable energy can still be utilized. However, higher rebound levels above 40% begin to significantly reduce the effectiveness of moving the load.
For 2035, the model estimates that load shifting could occur over thousands of time intervals, moving approximately 22.47 TWh of electricity, or roughly 7% of total semi-annual demand. This would reduce dependence on non-renewable generation during peak periods. However, these results remain highly sensitive to assumptions about consumer behavior, including the proportion of demand that is actually shifted and how rebound effects evolve over time.
A major limitation is that real-world consumption patterns during periods of free electricity remain unknown and may deviate significantly from model assumptions. “However, there may be some value in a modest, free midday electricity program in a market that doesn’t have much solar power, when the load curve is very low around noon and very high in the evening,” says Galvin. “We should look at the load profiles of specific countries and assess how steep the curves are.”
Overall, the findings suggest that while Solar Sharer programs may become increasingly effective, careful design and adaptive management will be needed to ensure that the electricity shift is in line with actual renewable surplus, without causing excessive or unintended increases in demand.
“Based on a large number of informal discussions I have had in Germany, Britain and New Zealand, I believe the plan would be successful in changing a large enough proportion of consumer behavior for it to work effectively. Pensioners have told me that in their spare time they would wash and wash their clothes, charge their lawnmower batteries, and charge their electric car if they have one. Others have said they would buy batteries to store as much free electricity as they can. and would use it at other times of the day,” said the researcher.
“The idea of ’free’ electricity is exciting and motivating, especially when it is associated with helping to reduce CO₂ emissions,” he concluded. “However, we need to put the plan into practice and then conduct research into how people react to understand what would actually happen.”
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