Investments in rooftop solar, wind farms and hydro-power stations will be protected as the federal government makes changes to the renewable energy target.

The government will respond to a review of the RET conducted by businessman Dick Warburton within weeks.

Industry Minister Ian Macfarlane used a Committee for the Economic Development of Australia speech in Sydney to throw his weight behind the retention of the RET, which was put in place by the Howard government 14 years ago.

“Let me be clear – the government is not suggesting the RET should be scrapped,” he said.

“The government will not make changes that will impact those who have already made an investment – small or large – under the RET.”

This meant that nothing would change for those who have installed rooftop solar, and large-scale investments such as wind farms or hydro power stations will be protected.

Labor says the government is planning to ditch the RET, putting jobs and investment in jeopardy.

Mr Macfarlane said the only threat to the RET would come from a Labor opposition that chose to play politics instead of continuing the “long-standing bipartisan approach”.

RET policy – which mandates 20 per cent of electricity come from renewable sources by 2020 – needed to ensure the national energy market was not oversupplied, he said.

A low growth rate in electricity use this financial year meant there could be the equivalent of nine big power stations of excess capacity generation in Australia.

“So we need to be sure that the RET is delivered in a way that fits in with this new market dynamic, and is not adding undue cost to households and making industries uncompetitive,” Mr Macfarlane said.

The government is soon to release an energy policy document ahead of a new national strategy, or white paper, being released by the end of the year.

The minister weighed into the coal seam gas debate in NSW, saying the largest state needed to do more to shore up its own gas supplies instead of relying on other states.

Environmental groups and farmers say CSG is putting water resources and quality agricultural land at risk.

The imposition of development moratoriums and ongoing regulatory change had created an environment where investment in resource development had become all but impossible, Mr Macfarlane said.

NSW had large gas resources and strong demand and increasingly supply was the best way to combat rising prices.

While a proposed gas pipeline from the Northern Territory could ease shortages, the project would need to go ahead without government subsidies.