Households in Scotland would have to pay £875 a year more in energy bills under independence, Labour has claimed.
Jackie Baillie said the loss of UK renewables subsidies would lead to a price hike for consumers north of the border.
She made the claim as she hit out the First Minister for failing to support Labour plans to freeze energy prices if it wins the next UK general election.
Ms Baillie pressed Alex Salmond on the issue when she stood in for Johann Lamont at First Minister's Questions at Holyrood, as the Scottish Labour leader was attending the funeral of party veteran Tony Benn in London.
Mr Salmond highlighted SNP plans to cut fuel bills for consumers in an independent Scotland - which he insisted where better than Labour's proposals for a price freeze.
If the Nationalists are in power in an independent Scotland, they would remove levies for tackling fuel poverty and improving energy efficiency from bills, with these instead being paid directly by the Government.
This could cut energy bills for people in Scotland by 5%, or £70 a year, according to the SNP.
But Ms Baillie claimed fuel bills would increase if there was a Yes vote in September.
She said: "We operate in the UK energy market, we get a third of the overall UK budget for renewables, despite our population being one tenth.
"Independence would remove that. Independence would cost an extra £875 per year for each household to make up the renewables shortfall, that's the price of independence on families already struggling to pay their bills."
Mr Salmond said: "The SNP proposed a £70 cut for family energy bills, which by definition is rather better than freezing energy bills."
He also warned if Labour continued to support nuclear power, that would result in energy bills "going upwards".