Contact Energy has unveiled full year profits of NZ$117.5 million, exactly half last year's NZ$237.1 million after a shocker year of coinciding negative factors.

Contact Energy has reported a 50.4 per cent fall in full year net profit to $117.5 million, hurt by transmission constraints and the need to buy electricity at high wholesale prices in last winter's drought.

A ministerial review has recommended setting up a $5m fund to promote the benefits of switching power companies.

Today's Government review will not see a quick drop in electricity prices, says the Herald's energy writer.

An energy review recommends overturning a ban on lines companies selling electricity, introduced due to fears they would abuse their market power.