As part of Maryland Public Service Commission's approval for the deal, the companies agreed to several conditions, including selling Constellation's three coal-fired plants in Maryland to mitigate concerns over market concentration in the mid-Atlantic electricity grid. Until the plants could be sold, the companies agreed to sell power from those facilities as well as others in the region's wholesale energy market at a price it costs to operate the plants, said Exelon spokeswoman Judith Rader.
But because of a computer software problem, Exelon informed the commission this month that it "advertently violated" its commitment by selling power above the agreed-upon costs, according to the PSC. This took place between March 13 and 27.
Rader said the company is working with the grid operator to "adjust our invoices to ensure that we do not receive or retain any revenues that we shouldn't have received."
The PSC is holding a hearing on May 9.