The rapid uptake of electric vehicles could force the ACT's electricity grid to more than double in size over the next two decades, its operator has said.
Evoenergy wants regulatory approval for it to spend an extra $90 million expanding the capacity of the grid over the next five years.
The total cost of enhancing the network would be between $2.5 billion and $3 billion.
Peak demand in 2045 would be 2.25 times current peak demand, driven by electric vehicle take up and switching gas appliances to electric equivalents, the company has said.
"Our modelling shows us that to achieve net zero emissions by 2045 we will require additional investment in the order of $2.5 to $3.0 billion beyond what we would have needed under a business as usual, no growth scenario," the company has said.
The company has asked for a total of $521 million for the period between 2024 and 2029, which needs to be approved by the Independent Competition and Regulatory Commission.
Evoenergy general manager Peter Billing said the total capital funding for the 2019-24 period was about $360 million.
The increase to the average residential bill over the next five years, not taking into account inflation, would be $7, he said.
As gas and fuel use drops, the use of the electricity grid increases and moderate bill rises, Mr Billing told a parliamentary inquiry.
"That's purely from the side of our bill. Our bill is one quarter to 30 per cent of the total electricity bill. We don't control the costs outside of that," he said.
The Legislative Assembly inquiry into electric vehicle adoption on Thursday also heard Evoenergy had modelled the impact of vehicle charging but there were was still uncertainty in
Mr Billing said the grid operator would adjust the model as more information became available.
"What we've done with the modelling to date is to get a sense of what it might look like in 2045 ... so that we've had the opportunity to look and say what would our business need to look like," Mr Billing said.
Leylann Hinch, the company's group manager of strategy and operations, said Evoenergy was still searching for new data sources.
"[It's] rapidly changing. We are taking every available source. We are looking at EV grid trials. We've been involved in some trials, but the cohorts are fairly small. We are certainly looking at charging patterns," Mr Hinch said.
Evoenergy's submission to the regulator said it would continue to find ways to reduce the "dramatic increase in peak demand" expected as the grid operator becomes the key energy provider in the ACT.
Mr Billing told Thursday's inquiry hearing that upgrades would be concentrated at the zone substation level, which step electricity down from 132,000 to 11,000 volts for areas.
Different zone substations have different usage profiles, depending on the areas they serve, whether residential or commercial, he said.
Evoenergy has also proposed to the Australian Energy Regulator charging ACT households more to feed solar power to the grid in the middle of the day.
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.
with AAP
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