Higher prices for renewable energy and distribution in the ACT will drive an $87 increase to the average territory household power bill over the two years from June, the Australian Energy Market Commission says.
The average annual bill for a typical residential electricity customer would rise by 5 per cent between June 2019 and June 2021, according to the commission.
The average annual bill will rise from $1717 in the current financial year to $1804 in 2020-21.
It is the second-highest estimated percentage rise in power bills in the country, behind Western Australia. Bills in every other state or territory, except the Northern Territory, are forecast to fall over the same period.
This year, the average electricity bill in Canberra is $423 more than across the border in NSW, and $621 more than the average bill in Victoria.
Canberrans pay Australia's fourth-highest electricity bills, behind the North Territory, South Australia and Tasmania.
The report also found 12.7 per cent of the average Canberra power bill goes to paying for the city's renewable energy, the highest proportion in the country.
The wholesale price is expected to fall in the next two years due to increased electricity supply in the market - although it increased by 17 per cent in 2017-18 and 2018-19.
But despite the falling wholesale price, rising network and environmental policy costs are set to drive up costs overall for ACT residents.
A 1.2 per cent decrease in electricity prices in 2019-20 will be followed by a 6.3 per cent rise in 2020-21.
The report also found ACT customers on standing offers could save $286 by switching to a lower market rate.
Market rates are set by energy retailers, allowing them to offer discounts and other incentives.
Customers who don't sign up for a market rate are put on the retailer's standing offer, which offers fixed, but usually higher, prices.
In the ACT, 68 per cent of residential customers are on standing offers, the report said.
Australian Energy Market Commission chief executive Anne Pearson said managing the costs of connecting a new generation would be a major challenge.
"We must avoid over-engineered solutions to stop gold plating and price spikes," she said.
Mrs Pearson said the report helped state and territory governments to understand what issues affected electricity prices in their jurisdictions.
"Understanding what's driving prices can help give state and territory governments the information they need to help determine if price changes announced each year by retailers are consistent with changes in the power system's underlying costs," she said.
The forecast price rise comes after an ACT government report found the territory's move towards 100 per cent renewable energy added almost $72 to the average power bill last financial year.
Climate Change Minister Shane Rattenbury has said there should be no net costs to Canberrans arising from the scheme from 2026.
A feed-in tariff scheme in the ACT pays a guaranteed price to a number of large-scale solar and wind power generators who supply electricity to the grid, paying them for the energy they feed in for 20 years.
A report released by the Australian Energy Regulator last week showed ACT consumers paid the highest price for gas in Australia, with middle-income ACT householders paying $1594 a year for gas in 2017-18, a rise of $332 on the previous year.