Queensland’s state-owned energy companies are making some serious money, and consumer advocates want to know why it has led to lower bills.

Energex paid $1.3 billion in dividends to the State Government in the 2014-2015 financial year, a near tripling of the $406 million the year before.

The state’s other power company, Ergon, reportedly increased it dividends from $400 million to $1.9 billion over the same period.

With profits more than doubling in a single year, the Alliance of Electricity Consumers lobby group wants to know why costs for customers have stayed the same.

“Energex and Ergon are responsible for moving the electricity from the power station through to your house or business or industrial centre. They're the poles and wires that run up and down your street,” Alliance spokesperson Jonathan Pavetto told reporters this week.

“The cost of running their businesses hasn't materially changed in the past 10 years, yet the price of their services has increased by 300 per cent.”

He said the State Government was taking dividends and profits from consumers of about 25 per cent – the equivalent of one entire quarterly bill going straight into state coffers.

An Energex spokesperson said anyone who claimed profits had doubled was misreading the numbers.

The company says revenues and profits have in fact stabilised, while operating expenses have actually fallen.

Energex says its increase in profit from $377 million to $730 million in the 2014-2015 financial year was due to a change of accounting processes.

This shift is outlined in the five-year historical summary in the annual report.

But the Alliance of Electricity Consumers says the power companies are over-charging consumers in order to cover the interest on their debts.

The lobby says consumer charges should be in line with the state's actual borrowing costs, not the private sector debt rate.