Millions of residential electric customers in eastern and central Pennsylvania will see a surprise rate hike on their PPL electric bill starting June 1 if they continue to buy their power supplies from PPL.

That's because PPL's generation supply rate, called the Price to Compare, for residential customers will increase to 9.036 cents per kilowatt-hour (kWh).

The current PPL residential Price to Compare is 8.754 cents per kWh.

While the hike is only about 3 percent, it does come as a jolt to customers, because PPL had actually been forecasting a small decrease in the residential Price to Compare starting June 1.

Prior to announcing the official June 1 Price to Compare, PPL's "estimated" residential Price to Compare had been 8.3670 cents per kWh.  The official June 1 Price to Compare of 9.036 cents per kWh is about 8 percent higher than the preliminary estimate.

The Price to Compare is the electric rate charged by PPL for customers who do not choose an alternative electric supplier and continue to buy their power supplies from PPL under a program known as default service.

The Price to Compare changes every three months to reflect changes in market conditions and prices.

Customers who shop around for an electric supplier avoid, or "bypass", the Price to Compare, and instead pay an electric rate negotiated with their chosen electric supplier.

PPL serves about 1.4 million customers in Harrisburg, Allentown, Scranton, Wilkes-Barre, Lancaster, and surrounding areas.

In the future, PPL customers could see changes in the way PPL sets its default electric rate.