Federal Labor has pointedly left open supporting Malcolm Turnbull's "game-changing" energy reliability package despite launching a spirited parliamentary attack over claims that household power bills would be cut by an average of $115 a year after 2020.

Sources admitted the opposition had serious criticisms of the process, including the government's inability to specify key aspects of its proposal, but said the national interest "probably dictated" that the "energy wars", must be brought to an end.

Rhetorically, the wars continued with Labor leader Bill Shorten using a visit to a solar farm near Canberra to brand it "a joke of a policy".

"This is not good economics, it's not good for climate pollution, it absolutely provides no guarantee for Australians, other than the guarantee this policy won't work," Mr Shorten said, before carrying his attack to the Parliament.