Electric Power
Electrical power explained: the three forms of the power formula, real versus apparent power, and why your bill is in kilowatt-hours rather than kilowatts.
Questions people ask
Why do generators get rated in kVA rather than kW?
Because the generator has to supply the apparent power, including the reactive part it never gets paid for. A 10 kVA set only delivers 8 kW into a load with a power factor of 0.8.
Is a higher power factor always better?
Yes for efficiency — it means less current for the same useful work, so smaller cables and lower losses. Large industrial users are often charged a penalty for a poor power factor.
How do I work out running cost?
Multiply the power in kilowatts by the hours used, then by your price per kWh. The energy cost calculator does it for you and shows the monthly and annual figures.
Does this page work offline?
Yes, after the first visit. The service worker caches it, so the reference stays available with no connection.
Last updated 22 August 2026