Two major energy providers have floated the idea of charging NSW and ACT households more to feed solar power into the grid during the day.
The new feed-in tariffs would affect households during the sunniest part of the day, under proposals from Evoenergy and Essential Energy to the Australian Energy Regulator.
The proposed charges were called a "sun tax" on Friday by a community solar panel lobby group, who said the charges would lead to higher energy costs for households and businesses.
Evoenergy put up a tariff called the "solar soak", charging customers for selling energy back to the grid between 11am and 3pm.
The company described the tariff as being of "relatively low" cost.
"These days more than 20 per cent of our energy users (in the ACT) have solar panels to generate electricity for their own use or to export back to the grid, and this number is growing," Evoenergy wrote in an overview of their submission to the regulator.
Essential Energy has proposed a "sun soaker two-way tariff" where residential solar customers producing more than 1.5 kilowatt-hours, with an interval or smart meter, would be charged to feed energy into the grid between 10am and 3pm.
If accepted by the regulator, the tariffs would take effect over the 2024-2029 regulatory period.
No final decisions have been made on the tariffs, and the regulator is currently holding consultations over the proposals and will hold public forums beginning in March.
Community solar lobby Solar Citizens argued the tariffs would cause energy bills to rise, estimating that homes with a 5kW solar system could face bill increases of $30 a year.
"An extra $30 per year might not sound like much, but that's just the starting point," Solar Citizens deputy director Stephanie Gray said, adding they were likely to increase over time.
"The other justification for these charges is to encourage solar owners to use more electricity during the day and export solar in the evening.
"But how many working families will be able to shift their main electricity use to the middle of the day and afford a battery so they can export at night?"
Homeowners in Queensland, NSW and South Australia faced feed-in cost increases in 2017 when AGL raised tariffs for residential customers by between 77 and 140 per cent.
The increases were used to offset rises in wholesale market prices, the company said at the time.
AAP has contacted Essential Energy and Evoenergy for comment.
