Failure to build the cross-border electricity interconnector is costing consumers across Ireland £25 million a year, it was revealed.
The development is planned to link the grids of Northern Ireland and the Republic to produce cheaper energy costs. Some residents on the route along the Monaghan-Tyrone border are unhappy at the prospect of new pylons being built across the countryside.
Stormont Energy Minister Arlene Foster said there was a need to "get to grips" with restrictions on the electricity system in Northern Ireland.
"The constraints are caused by the Moyle interconnector only working at half capacity and the fact that the North/South interconnector has not become a reality," she told the Assembly.
"Because of the fact that we don't have the North/South interconnector, that is costing the consumer in the Republic of Ireland and in Northern Ireland £25 million a year.
"Everybody in this House should be concerned about that because we often talk about the cost of electricity, about the cost of energy right across the piece from domestic consumers through to manufacturers, and the fact that we have a constraint like that on our system should be something of concern right across the House."
The minister stressed that the electricity grid needed to be capable of dealing with extra supplies from renewable sources.
A battle has been fought between proponents of a plan to build an interconnector on pylons from the Republic through Co Armagh and residents and landowners who fear its impact on the environment and health.
The Consumer Council has called for a cross-border link at the lowest cost to the consumer, which is to mount the connector on pylons rather than burying the wires underground, separate research for the UK Government has shown. According to the Consumer Council, the average electricity bill in Britain last year was £530 a year compared with £588 a year in Northern Ireland.
It said consumers were bearing more risk from higher costs than shareholders in electricity companies and prices were greater because energy policy is "confused and contradictory".