General buying guidance only. It is not an engineering design, compliance determination or product specification.
Power describes a rate
kW is the rate at which a system supplies or absorbs energy at a point in time. Peak demand, continuous load and short surge demand may all differ.
Energy describes an amount
kWh is an amount of energy over a period. A battery’s nominal energy is not automatically the usable energy available to a particular load.
Duration depends on more than division
Dividing a battery’s nominal kWh by a load in kW does not produce a dependable backup promise. Usable capacity, conversion losses, reserve settings, temperature, battery limits and the changing load all affect the result.
What to put in a first brief
Record the load that matters, when it runs, what must stay powered, and whether the values are measured or estimated. Leave the technical design and runtime calculation to the responsible project team.