Kilowatt-hour (kWh)
A kilowatt‑hour (kWh) is the amount of energy delivered or consumed when one kilowatt of power is used continuously for one hour.
What a kilowatt‑hour measures
A kilowatt‑hour (kWh) is a unit of energy, not power. Power tells you how fast energy is used (kilowatts, kW); energy tells you how much has been used over time. When you multiply power (kW) by time (hours), you get energy (kWh).
How it works
- Power (kW): the rate at which electricity flows, like the speed of a car.
- Time (h): how long that rate is maintained.
- Energy (kWh) = Power × Time.
If a 2 kW electric heater runs for 3 hours, it consumes 2 kW × 3 h = 6 kWh of energy.
Why it matters
Utilities bill customers in kWh because it reflects the total amount of electricity a household or business actually uses. Understanding kWh helps you compare appliances, estimate costs, and plan energy savings.
Concrete example
The average Israeli household uses about 900 kWh per month (≈30 kWh per day). A typical 1 kW rooftop solar panel, under Israel’s sunny climate, produces roughly 4–5 kWh per day. Over a month, that panel can offset about 15‑20 % of a household’s consumption.
Relevance to solar energy in Israel
- Solar sizing: To replace a 900 kWh monthly demand, you’d need a system that generates ~30 kWh per day. With an average yield of 4.5 kWh per kW of panels, a ≈7 kW array would do the job.
- Net metering: Israeli net‑metering rules credit you for each kWh your panels feed back to the grid, effectively lowering your bill.
- Cost comparison: If electricity costs 0.65 ₪/kWh, each kWh you generate saves that amount. Over 20 years, a 7 kW system can save ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ ≈ (the exact figure depends on usage and tariffs).
Understanding the kilowatt‑hour lets you see how much energy your solar system actually produces and how it translates into real‑world savings.