MONTGOMERY — The state Public Service Commission has approved a plan for Alabama Power Co. to offer a $20 annual discount to customers who agree to let their home air conditioning be cut off for brief periods on hot summer weekdays.

Alabama Power would install devices on home air conditioners that would allow them to be cut off for 15 minutes out of each 30-minute period when power demand is at its peak. That occurs on weekday afternoons between June and September.

Customers who sign up for the new program would receive a $20 savings on their November bills.

Alabama Power will begin offering the program in the Birmingham area and plans to have it statewide by the end of 2010. An Alabama Power spokesman says most customers would never know the difference because they would be at work when the program was in use.