How Power is Measured
A kilowatt hour, shortened to kWh, is a standardized way to measure how much electricity someone uses. It’s the basic unit your solar system produces, and the utility company measures, to figure out your energy bill.
But what does it really mean?
- A kilowatt (kW) is a unit of Power — kind of like how fast water is flowing through a pipe. For example, a 1,000-watt (or 1 kW) microwave uses 1 kilowatt of power while it’s running.
- A kilowatt hour (kWh) is a measure of Energy — the amount of electricity used over time. If power is like the flow rate of water, energy is the total volume of water. Energy is measured in watt-hours (Wh) or kilowatt hours (kWh). One kilowatt hour means you’ve used 1,000 watts of power continuously for one hour (that would be some burnt toast!).
Understanding kWh on your Bill
When you get your utility bill, it will show how many kilowatt hours (kWh) you drew from the grid during the billing period. Customers with solar panels and a Net Metering agreement will also list how many kWh of excess solar power were sent back to the grid. These extra kilowatt hours are added to (or withdrawn from) your “Net Meter bank”. This balance tracks how much energy you’ve saved for later use, especially during times when your solar panels aren’t producing enough electricity.