system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Electricity can't be stored, so when a light gets turned on, the power station must immediately produce some extra electricity. How is this possible?
gpt
As a unit of one, your house's power usage varies wildly and is somewhat unpredictable. 

As the unit of your residential city block of 20 homes, the small variations in personal schedules cancel out and power usage is more statistically stable.

As the unit of your neighborhood of 10000 homes and 100 small businesses, the variations are even smaller.

As a unit of your city of a million residents and businesses, the profile of consumer is pretty steady and predicable.