If the goal of the Government was honest, ie. they want us to use less electricty, the surest way would be to simply add a surcharge to everyone's electricity bill, like the GST is added. That would work well, and achieve the goal.
Might not be too popular with voters though.
No, much better to put a tax on the nasty power companies, who everybody loves to hate, - and let them cop the flack for the higher electricity prices.