Companies have been forced to meet the short fall through higher priced thermal gas and coal generation, he said.
Consequently, wholesale electricity prices have nearly doubled from an average electricity price of about $49 per MWh in 2011 to $94 per MWh in 2012.
PwC's analysis of the five largest firms in the electricity sector - Contact Energy, Genesis Energy, Meridian Energy, Mighty River and TrustPower - found total revenues increased nearly 23 per cent in the 2012 financial year.
"While as a headline this is impressive, this revenue growth does not translate into earnings growth, due to correspondingly higher electricity generation and acquisition costs," Taylor said.
Across the sector, overall electricity earnings dropped slightly in the year.
The ongoing impact of the global financial crisis has also been a key issue for the sector as major consumers have changed the way they operate.
Less production means less electricity needs, and that combined equals stagnant demand conditions, Taylor said.
"With demand growth stalling, many generation development options are being delayed or put on hold.
"During the last financial year, there have been no significant generation plants commissioned, although there are a number of generation developments currently under construction."
In terms of 'customer churn', the number of customers changing suppliers has plateaued at between 30,000 and 35,000 per month.