Peak demand is the moment of highest electricity use. It usually comes in the late afternoon or early evening, when homes and businesses draw power at the same time. In hot regions, summer peaks spike with air conditioning. In cold regions, winter peaks rise with heating.

Utilities must build enough capacity to meet the peak, even if it lasts only a few hours a year. That capacity is expensive. Peaking plants, often gas turbines, sit idle most of the year and fire up when needed. They produce the most expensive electricity on the grid.

Managing peak demand is a major focus. Demand response programs pay large users to cut back. Smart thermostats cycle air conditioners. Time-of-use rates encourage customers to shift laundry and dishwashing to off-peak hours. Batteries discharge into the evening peak. As electrification grows, peak demand will rise, and managing it will matter more.

Common strategies

• Demand response programs
• Time-of-use pricing
• Battery storage
• Peaking power plants
• Energy efficiency upgrades