The government has defended offering tax breaks to businesses to become more energy efficient for a single year only, saying it will help employers overcome the short-term crisis.

Some 3.8 million small and medium businesses can access a concession that could net them up to $20,000 worth of extra tax deductions for becoming more energy efficient between July 1 this year and June 30, 2024.

Assistant Energy Minister Jenny McAllister said previous experience showed there was an "enormous appetite" from the business sector to take advantage of investment assistance.

"This measure is really designed to stimulate business investment in energy savings in a period where we know that energy costs are weighing on small and medium-sized businesses," she told AAP.

"We're looking to catalyse a range of quite short-term investments in business that will help them through this immediate period of crisis."

But the managing director of Smart Commercial Solar said the measure won't stimulate small businesses in the short-term as only those who can afford to will take it up.

Huon Hoogesteger said businesses doing it the toughest in this economy and climate would not have the spare funds to put against non-essential upgrades.

"So, this money will be wasted on businesses that could already afford to spend that extra money and who are already doing something," he said.

Senator McAllister said the combination of the government's measures in the budget, including incentives to make households more energy efficient and money to upgrade social housing, would pave the path to net-zero.

"It's a pretty long-term project," she said of the transition to cleaner and more efficient energy.

"But the budget measures essentially are a down payment on that strategy."

The assistant minister said upfront costs were one of a number of impediments stopping home owners upgrading to more energy efficient technology.

"We're really designing these (measures) with a focus on giving households and businesses greater choices," she said.