AGL has almost doubled its first-half net profit.

The energy utility and retail giant says the $622 million profit for the six months to December 31 represents a 91 per cent jump on the previous corresponding period, driven by its wholesale market business.

The profits come from a period when household power prices soared.

“The increase reflected strong margin growth in its wholesale markets, which more than offset a small decline in customer [retail] markets margin and planned increases in operating expenditure,” AGL said in a statement to the ASX.

The company says it is aware that while its profits soar, high energy prices are hitting customers hard.

“We are committed to delivering further solutions to customers in coming months and in doing all this at the lowest possible cost,” AGL CEO Andrew Vesey said.

Mr Vesey expects wholesale prices to have peaked for now.

“Lower spot prices and lower volatility mean the moderation should continue,” he told an investor briefing.

Mr Vesey said changes in the market were creating downward pressure on retail margins, not just state and federal governments.