But energy prices will rise after 2030, a study has found, as companies are forced to replace energy infrastructure of all kinds.
The CSIRO released the findings in its 2026 GenCost report, which also warned small and large nuclear reactors were still among the most costly energy options.
Electricity and environmental groups welcomed the report on Wednesday, saying the results reinforced the need to invest in renewable energy, but opposition energy spokesman Dan Tehan called long-term price rises an indictment of Australia's net-zero target.
The eighth annual GenCost report, prepared with the Australian Energy Market Operator, analysed the cost of generating electricity using different technologies - from black coal and large nuclear reactors to gas and solar panels.
Researchers calculated the average cost of producing electricity in 2030 and 2050, and found solar panels and onshore wind farms were consistently the cheapest energy sources.
On the other end of the scale, small modular nuclear reactors and black coal with carbon capture and storage were the most expensive options, followed by large-scale nuclear reactors and gas with carbon capture.
Electricity prices would continue to decrease in the next three years, the report found, dropping from $104 per megawatt-hour in 2025 to between $80 and $90 in 2030.
But the price of gas turbines would keep rising for the next two years, GenCost lead author Paul Graham said, as the technology was deployed to power more data centres.
"Something we had to take into account when we were doing our short-term projections for gas turbines is the US strategy of building data centres, big data centres, trying to build them quick, and often deciding to build dedicated gas turbines," he told AAP.
"That has actually made US data centres the second biggest (consumer for) gas turbines in the world."
Energy costs would climb in Australia after 2030, the report found, as ageing assets were replaced.
The findings highlighted the need for data centres to be powered by cheaper renewable energy, Climate Council chief executive Amanda McKenzie said, while Australian Energy Council chief executive Louisa Kinnear said the report validated existing investments.
"Firmed renewables is the cheapest way to replace exiting generation - that is not up for debate," she said.
"But it is time for an open and honest conversation with Australians about the costs and challenges of the transition and what it means for their energy bills over the long term."
But rising long-term energy costs could be partly attributed to Australia's net-zero target, Mr Tehan said, and would hit household budgets.
"Pursuing energy abundance, where all technologies can play a role in Australia's future, can deliver cheaper costs," he said.
