Energy vs Power
Why kilowatt-hours and kilowatts describe different things—and why confusing them creates bad system decisions.
Where this fits
Why kilowatt-hours and kilowatts describe different things—and why confusing them creates bad system decisions.
Core system ideas
Energy measures a quantity accumulated over time; power measures an instantaneous or average rate of transfer.
A device drawing 10 kW for two hours uses 20 kWh of energy.
Grid planners care about both: energy adequacy over hours or seasons and power capacity during peaks.
Interfaces and tradeoffs
The most useful way to understand this topic is to place it in the chain from energy conversion to customer service. Definitions, units and system boundaries should be explicit before comparing technologies.
What organizations measure
Peak kW/MW, energy kWh/MWh, load duration and capacity needs.