Close observers of household electricity usage have long puzzled over why consumers often complain about high power prices but when exposed to time-of-use tariffs tend not to adjust behaviour.
Add batteries, though, and that verdict may need to be revisited.
That’s the key finding of a new working paper by Bruce Mountain, head of the Victorian Energy Policy Centre: “Storage and Signals: Solar and Battery Storage, Time-of-Use Pricing, and Household Peak Demand in the Australian NEM“.
Retailer AGL provided Mountain access to anonymous consumption data from 5,096 households across NSW, Queensland, South Australia and Victoria. The information covered 30-minute grid import and export volumes, generating more than 3 million site-day observations over a three-year period to August 2025.
The findings may help grid managers and energy companies rethink how to coax consumer behaviour that eases the strain on power supplies during high demand periods. Maximising the gains flowing from the 540,000-plus households who have snapped up the federal government’s Cheaper Home Battery Scheme could also be an imporant side benefit.
Households providing data were split by solar and battery ownership status – no solar, solar only, solar plus battery. Those installing solar PV or a battery during the period were excluded.
As retail prices changed for many households during those three years, the data revealed how they altered behaviour in response to shifting peak and off-peak tariffs.
With those settings, the new paper investigated two related questions: First, do households consume less electricity during peak periods when the gap between peak and off-peak prices is wider?
Second, do households with solar panels and batteries have different patterns of peak electricity consumption than other households, and does this variance depend on whether they are actually on a time-of-use (TOU) tariff?
Mountain said the answer to the first question was “striking”, clearly confirming research he had conducted in 2021 with fellow researcher, Kelly Burns.
“There is no statistically significant evidence that households respond to the size of the peak-to-off-peak price difference,” Mountain wrote in a non-technical companion report. “This [result] applies to households without solar, households with solar alone and households with both solar and batteries.”
“Even when the analysis is restricted to those households that experienced the largest changes in relative prices, the result is essentially unchanged,” he wrote.
Mountain stressed the result did not imply electricity prices never matter to households.
Rather, there was no evidence of the particular form of response on which conventional TOU pricing is based, namely, that households would progressive shift consumption away from peak periods as the peak/off-peak price difference becomes larger, he wrote.
However, the second question, involving the behaviour of households with solar panels and batteries, provided what Mountain described as a “different and more interesting result”.
“The central finding is that households with solar and batteries consume significantly less grid electricity during peak periods than other households when they are actually on a TOU tariff,” he wrote.
“At the average level of consumption in the sample, the estimated difference is about 13 per cent compared with households without solar on the same type of tariff.”
However, battery households on flat tariffs did not show a similar reduction, with their peak-period consumption “statistically indistinguishable” from that of non-solar households on flat tariffs. Households with solar only also did not produce the same clear pattern.
The key takeaway was that TOU tariffs and battery policies appear to serve as complements.
“If the policy objective is to reduce household demand on the grid during peak periods, encouraging appropriate TOU tariffs for battery households may achieve more than attempting to induce behavioural changes from households generally,” Mountain wrote.
“The paper consequently suggests considering battery incentives and tariff policy together rather than treating them as separate policy instruments,” he wrote.
Mountain told Renew Economy he was not aware of such datasets elsewhere, particularly one that combined retail and network prices and volumes. “[It’s] a real credit to the retailer in making this available for public interest research,” he said.
AGL will provide the VEPC with more data next January, Mountains said. That additional information could help examine more of the effects of the Cheaper Home Battery scheme – which has encouraged households to install much larger batteries than previously.
The spread of electric vehicles may not follow the same pattern, Mountain said. EVs will bring “huge demand so [there’s a] powerful incentive to schedule charging at cost-effective times”.
The customers captured by the data did not include any on virtual power plant contracts, Mountain added.
“Scheduling to the tariff is much easier and is producing a large response that provides benefits for all.” he said. “VPPs are a hard sell, for good reason.”
