There was nothing to do but down tools and shut up shop. The dry cleaner sat on his hands as his store was bathed in darkness, while the cafe next door had to turn away dozens of customers.

During one blackout, cafe owner Taras Marciburko had to rush out and buy 20 bags of ice just to stop food from spoiling.

Business owners on the busy Hawthorn shopping strip say they are at breaking point after 11 blackouts this year, including four in the past week as the mercury soars across the state.

The blackouts affect several blocks and about 30 businesses, including a Bank of Melbourne branch, a Readings bookstore, multiple cafes, a dry cleaner, a butcher, a bottle shop and several retail shops.

A spokesperson for CitiPower said the blackouts were due to soaring energy demand from the thriving retail strip.

"As areas change, demand on local infrastructure also changes," a CitiPower spokesperson said.

"During the past year, there has been an increase in energy demand in this shopping strip, placing pressure on the local network.

"We made improvements [on Wednesday] that we expect will resolve this and planning is under way to upgrade the local network to cope with future demand."

As Victoria heads into summer with a strained energy network, Glenferrie Road business owners fear the blackouts will continue.

And there could be bad news for small business owners elsewhere.

This week's mild November heatwave and the recent failure of two coal-fired power units in the Latrobe Valley have drained the state's energy grid of reserve supply.

Dave Desson, owner of Debonaire Dry Cleaners, said the blackouts were devastating for his small business.

"First of all customers don't come in. Second of all, we end up having to remunerate our staff because everybody has to stay back and literally we have to stay here until 10pm at night to get the day's work out."

Mr Desson said the blackouts typically occurred between 10.30am and 2pm and lasted for hours at a time.

"The impact of something like this is just devastating. After a blackout, it takes us an hour to get back to full capacity.

"I'm just so shattered."

Mr Marciburko who owns Cafe Blac next door to Mr Desson said he had lost thousands of dollars of expensive kitchen equipment damaged by the power outages.

"I haven't been able to provide any services at all. We've turned away 40 to 50 people today alone," he said on Wednesday.

"Tuesday's outage was over lunch from about 11am to 2pm and today was 11am to 1pm.

"The food service is very competitive, so when you turn away customers it's not something you ever want to do."

Across the road, Graedon White, owner of Red White & Amber Liquor Merchants, said he was processing customers manually and was concerned with the busy Christmas period on the horizon.

"I've got a lady at the counter now with 12 bottles of wine now so can you imagine doing that for every customer?

"It was only 28 degrees on Tuesday at 11am when the power went. What's it going to be like when it's 40 degrees?"

Readings Hawthorn manager Desiree Boardman said the outages were frustrating and often meant they had to close their doors.

"The cafe which is attached to our shop has had to close its doors because they can't make coffee. Your business is affected by it."

Laurent manager Chanel Dubuisson said it was a juggling act trying to stop cakes from spoiling with no power to their fridges.

"We're still trading as much as we can," he said.