Free midday electricity schemes aim to shift household demand into periods of high solar PV generation, reducing midday surplus and evening fossil-fuel ramp-up. Research on Australia’s Solar Sharer program suggests such incentives could significantly improve renewable utilization, but outcomes depend on consumer behaviour, load shifting, and rebound effects.
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Free midday electricity is a key tool for encouraging consumers to use appliances and consume more power during hours of strong photovoltaic production, when electricity supply often exceeds demand, creating inefficiencies in the system. By lowering prices to zero or near zero, consumers are incentivized to shift their energy use to these periods, helping to align demand with renewable energy generation and reduce wasted solar power.
With this in mind, a researcher from Cambridge University, Ray Galvin, has investigated how the Solar Sharer program – set to launch on July in Australia – could pave the way for the adoption of similar incentives in other countries with high renewable energy shares.
Under this program, households with smart meters receive about three hours of free electricity during the middle of the day, when solar power is abundant. The time window starts between 11:00 am and 12:00 pm, depending on the state.
“The scheme could best be replicated in markets that have a substantial share of solar electricity,” Galvin told pv magazine. “This produces a wave of excess power around midday and a few hours either side, when the domestic electricity load is relatively low, but doesn’t produce in the evening, when most domestic electricity consumption occurs. This results in fossil-fueled electricity sources having to be ramped up in the evening. The Solar Sharer scheme aims to induce households to shift part of their loads away from the evening to the period when solar PV is producing excessively.”
Galvin explained that the length of the free midday free electricity period should be set to suit the average amount of excess solar power, which varies from country to country and from season to season within a country. “With Australia the seasonal difference isn’t that great, so they can set the period to suit the average time of excess solar generation,” he added. “With a European country it would need to be adjusted several times during the year. So, in my research, I’ve suggested a communication strategy between the electricity providers and the households, which could optimize the length of the free periods and keep households informed.”
In the paper “Free midday electricity in a Solar Sharer scheme: Should Germany follow Australia’s lead?” published in Renewable Energy, Galvin explained that two key behavioural-economic factors can shape the effectiveness of free midday electricity schemes: load shifting and rebound effects.
Load shifting refers to the extent to which households move electricity consumption from other times of the day into a free midday period. Rebound effects, by contrast, describe the tendency for total electricity consumption to increase when electricity is free or very low-cost, as users may run additional appliances or use energy less sparingly, partially offsetting the intended efficiency and grid-balancing benefits of the scheme.
Galvin’s analysis shows that Solar Sharer–type schemes could meaningfully increase renewable energy utilization, but their impact depends strongly on behavioural responses and system flexibility. The modelling suggests that a Solar Sharer scheme could already have been viable in Germany in 2025, provided it successfully shifts electricity use from periods of low renewable surplus to times when renewable generation exceeds demand.
A moderate rebound effect of around 20% does not significantly reduce the benefits in the model, which assumes that roughly half of available surplus electricity is shifted to peak-demand periods. Under these conditions, a substantial share of excess renewable energy can still be utilized. However, higher rebound levels above 40% begin to materially reduce the effectiveness of load shifting.
For 2035, the model estimates that load shifting could occur across thousands of time intervals, moving around 22.47 TWh of electricity, or roughly 7% of total half-year demand. This would reduce reliance on non-renewable generation during peak periods. However, these results remain highly sensitive to assumptions about consumer behaviour, including the share of demand that is actually shifted and how rebound effects evolve over time.
A key limitation is that real-world consumption patterns during free electricity periods remain unknown and may diverge significantly from model assumptions. “However, there may be some value in a modest free midday electricity scheme in a market that doesn’t have much solar power, if the load curve is very low around midday and very high in the evenings,” Galvin said. “We would need to look at load profiles of specific countries and assess how steep the curves are.”
Overall, the findings suggest that while Solar Sharer schemes could become increasingly effective, careful design and adaptive management will be required to ensure electricity shifting aligns with actual renewable surplus without triggering excessive or unintended demand increases.
“Based on a large number of informal discussions I’ve had in Germany, the UK and New Zealand, I do believe the scheme would be successful in changing a sufficient portion of consumers’ behaviour to make it work effectively. Retired people have told me they would do their clothes washing and dishwashing in the free period, charge their lawn mower batteries, 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 use it at other times of the day,” the researcher said.
“The idea of ‘free’ electricity is exciting and motivating, especially when it’s associated with helping reduce CO₂ emissions,” he concluded. “However, we need to get the scheme up and running, then conduct research on how people respond, to understand what would actually happen.”
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