kVA vs kW — explained (with a beer)

Imagine you order a pint of beer. The total volume in the glass — the beer plus the foam — is the apparent power, measured in kVA (kilo volt-amperes). The beer itself, the part you actually drink, is the real power, measured in kW (kilowatts). The foam sitting on top is the reactive power, measured in kVAr — it takes up space and you paid for it, but it doesn't do useful work for you. The ratio of real beer to total glass volume is called the power factor (PF). A perfect glass of all beer, no foam, is PF = 1.0. A pint that's half foam is PF = 0.5. Most industrial generators are rated at PF = 0.8.

Both — but in different ways: • Sizing against the load: add up the running watts of every appliance you want to run. That's kW. A house with a fridge, lights, fans, and electronics typically draws 4–6 kW. • Sizing the alternator: account for starting surge of motors. An air-conditioner that runs at 2 kW can draw 6 kW for 200 ms on startup. That short surge is measured against the kVA rating. Rule of thumb for residential: a 7–10 kVA / 5.6–8 kW generator covers a typical 4-bedroom Australian home. For commercial sites, always build a proper load schedule with us — we do it for free.