A PUC audit found that FirstEnergy Corp.’s Pennsylvania subsidiaries overstated their Energy Efficiency and Conservation Program costs in 2010 and 2011 by mistakenly applying Ohio’s higher sales tax rates on purchases of items such as home energy audit kits. The company agreed with the audit finding and has corrected the error. The audit found Pennsylvania Power Co. and Pennsylvania Electric Co. had net overcollections of more than $1 million each but Metropolitan Edison Co. undercollected by about $7.3 million despite the error.