The Grattan Institute, IMHO the best think tank around here, has put out a report on the energy industry.
An article from Lucy Percival out;lines its main points.
The Report is here written by Tony Wood and David Blowers.
It outlines the reasons why costs have risen over the last few years.
The largest is caused by changes in supply.
Almost as bad is caused by increases in prices of inputs mainly gas and coal prices.
Lastly and on a very small basis is companies gaming the system.