EDMONTON -- The law of supply and demand kicked Albertans in the pants again Tuesday -- the cost of flipping those lights on rose from over a penny in the wee hours to almost a dollar by the afternoon.

The Alberta Energy System Operator said a new summer record for demand of 9,885 megawatts set at 2 p.m. Monday was all part of a coincidence that prompted it to tell providers to shut 'er down in some neighbourhoods across the province for only the second time in a decade.

The kicker is that, as it stands, Albertans may never know why.

On Tuesday, electricity utility EPCOR said they wouldn't release the number of customers or locations affected by rolling blackouts Monday for security and market reasons.

Just what shut down six out of 35 generators in a record scorching heat wave will also remain under wraps.

"This increased demand, coupled with the unplanned outage of four coal-fired and two gas-fired generators, created a need to reduce electricity consumption across the province," said an AESO press release.

Energy Minister Ken Hughes said it's all right for the causes of shut-downs not to be revealed.

"The power generators are certainly within their current authority not to reveal details of vulnerabilities like that either for competitive or security reasons," Hughes said.

On a rolling basis, providers blacked out portions of the province -- reducing their customers temporarily -- at the same time that six of the province's generators went down while prices for customers not tied in to fixed rates saw their costs go through the roof.

Wildrose Party energy critic Joe Anglin called the shut-down "suspicious."

He said there's room for competition, but what Alberta has now is price gouging.

Alberta's wholesale electricity market had about 164 participants and roughly $8 billion in annual energy transactions in 2011, according to AESO.

Instead of a true free-market system, Albertans have a monopoly in Calgary, a semi-monopoly in Edmonton and a hodgepodge province-wide, Anglin said.

"What's wrong with the system is that it doesn't really cost any more to make that electricity at 3 p.m. than it does at 3 a.m. They've manipulated the pricing mechanism," he said."This is not rocket science ... it is price fixing."

Anglin said he's preparing a report for the fall detailing an alternative to the current system.

Hughes said the event was rare -- just the second occurrence in a decade of deregulation -- and pointed to the importance of two things: robust generation and robust transmission.

The transmission part, outlined in Bill 50's new north-south transmission line, is what the Wildrose takes exception to in their efforts to repeal the bill.

The province should invest in the infrastructure to ensure a really robust -- and, where necessary, redundant -- transmission system so we can access power generation throughout the province and offset generation capacity when it's not available to the system, Hughes said.

The province has more companies looking at getting into or expanding the power-generating business in the province, he said.

"In Alberta, we're going to have another million people in a decade. We're going to need to continue to grow an electricity system that meets the needs of the people of Alberta," he said.