kW vs. kWh: two numbers, two jobs.

A kilowatt (kW) measures power at a moment in time. A kilowatt-hour (kWh) measures energy used or stored over time. One kilowatt used continuously for one hour equals one kilowatt-hour.

Think about what runs together.

Power output matters when several loads run at the same time. Storage capacity matters when you ask how long energy could last. Comparing batteries using only one number leaves out part of the picture.

A simple example.

If 10 kWh were available to your loads and they used a constant 1 kW, the arithmetic gives 10 hours. At 2 kW, it gives 5 hours. These are idealized calculations, not a system runtime promise.

Then ask about real-world limits.

Ask the designer to account for reserve settings, starting charge, conversion losses, startup requirements, and changing usage. Request both the equipment specifications and the assumptions behind a runtime estimate.