Canonical Definition
Peak demand is the highest level of electricity use over a defined interval, applicable both to an individual customer (their maximum demand during a billing period) and to the grid as a whole (the system peak, often on hot summer afternoons or cold winter mornings). Customer peak demand drives demand charges on applicable rates, while system peak demand drives infrastructure sizing and costs. Reducing usage during peak times can lower system costs and, under some rate structures, may lower a customer's bill.
Explanations
Peak demand is the highest amount of power used at one time. For your home, it is your biggest burst of usage during the billing period. For the grid, it is the time when everyone's usage adds up to the most, often on very hot or very cold days. Utilities must build enough equipment to handle these peaks, which is why some rate plans charge more during peak hours or for high peak demand.
Peak demand is the moment when the most power is used at once. It can be in your home or across the whole grid. It is like rush hour, but for power.
Analogy Bank
Peak demand is like the dinner rush at a restaurant — the kitchen has to be staffed for the busiest hour, not the average one.
Your home's peak demand is like the moment everyone showers at once — the biggest simultaneous pull on the system.
For the grid, peak demand is like a stadium crowd all leaving at the same time; the exits must be sized for that surge.
Do Not Say
- ✕Do not promise that shifting usage off-peak will lower a customer's bill; the effect depends on their rate structure.
- ✕Do not state when system peaks occur for a specific utility; timing varies by region and season.