The regulator said while there is a clear public interest in preserving some commercially sensitive information in the audit conducted on its behalf by Liberty Consulting Group, the same doesn't apply to criticisms of Nova Scotia Power.
"Granting NSPI's request would set a troubling precedent as the board fully expects that NSPI would attempt to use it to shield future criticisms from public view," the board said in its decision.
The audit was released in July but heavily redacted at Nova Scotia Power's request. It said the private utility company owes its customers a refund because it paid too much for fuel over the past two years.
Nova Scotia Power has disputed the audit's conclusions. Last month, it filed an affidavit with the board in a bid to prevent it from being released to the public, arguing that it is defamatory, would violate the privacy of employees and break contractual confidentiality.
The company said it wanted certain sections of the audit kept under wraps until the board released a decision on their merits on Oct. 29.
But the board said Nova Scotia Power has had the opportunity to file "considerable" rebuttal evidence that it can air during the upcoming hearing.
The board also said the public interest in disclosing portions of the audit outweigh the private confidentiality concerns expressed by Nova Scotia Power, and it didn't believe the release of criticism of the company's fuel purchases would impair its ability to buy fuel or carry on with its business.
In a statement, Nova Scotia Power said it accepts the board's decision but maintains that the audit's conclusions are wrong.
"We absolutely agree that the public has a right to know the facts," said Rene Gallant, the company's vice-president of regulatory affairs.
"We work hard to keep fuel costs as low as possible for our customers, and we maintain that our fuel purchases and hedging programs have been prudent, and have saved money for our customers."
Progressive Conservative Leader Jamie Baillie, who wrote to the board asking it to review the redaction of the audit, applauded the decision.
He said Nova Scotia Power executives should have to defend their actions in public.
"It was really a test of whether the public could continue to have some confidence in our regulated system," Baillie said in an interview.
"The reputation of the power company and the auditor is on the line and the public will get to see."
Energy Minister Charlie Parker also supported the board's decision.
"Ratepayers have a right to see this information and we need the full picture to ensure Nova Scotians are paying the lowest, fairest rates," Parker said in a statement.
The board has ordered Liberty Consulting Group to provide an updated version of the audit "as soon as conveniently possible."