Kilowatt-Hour (kWh)
The standard unit utilities use to bill electricity, equal to using one kilowatt of power continuously for one hour, and the same unit a net metering program uses to credit solar power sent back to the grid against power drawn from it.
Why it matters
Nearly every number on a utility bill, and every number describing a solar system's output or net metering credit, is expressed in kilowatt-hours. It's a unit most people have seen without ever being told exactly what it measures, which matters once someone has to actually evaluate a solar proposal or a net metering credit.
On a real project
A solar system is sized to offset a household's typical monthly usage of roughly nine hundred kilowatt-hours, and net metering credits the homeowner one kilowatt-hour against their bill for every kilowatt-hour of solar power the system sends back to the grid.
Who this matters most to
A Solar Installer sizes a solar system against a customer's actual kilowatt-hour usage history, pulled from past utility bills, rather than a rough guess at the household's needs.
Where this goes wrong
A solar proposal quotes a system's output in a way that sounds impressive but doesn't actually match the customer's real kilowatt-hour usage from their own utility bills. The system ends up oversized or undersized relative to what the household actually needs to offset.