Pennsylvania residents who have not opted to choose an alternative energy supplier will face higher electricity rates beginning June 1, according to a PPL Electric Utilities filing with the Pennsylvania Public Utility Commission.

CBS News 21 reports the utility stated that higher rates are due to larger supply portfolio costs, including estimated market costs for the summer months, when demand typically spikes. The hike also marks an annual transmission rate update, as set by the Federal Energy Regulatory Commission.

The higher electricity rates will not affect customers who have chosen to use an alternative energy supplier, many of whom will see lower prices when they compare electricity rates between PPL and their supplier. Currently, more than 30 retail electricity suppliers are operating in PPL's service area, according to the news source.

"Alternative suppliers can offer options that PPL Electric Utilities does not, such as the ability to lock in a price for a longer term," said Dennis Urban, senior director of Rates and Regulatory Affairs for the utility. "We encourage all customers to look at available offers from alternative suppliers, weigh the terms and conditions, and choose what is best for them."

More than 580,200 PPL customers – or 41 percent – receive their power from alternative suppliers.