The question we get most often on WhatsApp — usually phrased as "just tell me which generator to buy" — deserves a better answer than a model number. Undersize and the genset trips or cooks itself every blackout; oversize and you pay tens of millions of rupiah extra upfront, then slowly damage the engine by running it at a fraction of its load. This guide shows you how we actually size villas, with the same numbers we use on surveys.
Step 1 — Add Up What Actually Runs
List everything that draws power during a blackout. Not the whole villa nameplate — the realistic simultaneous load. A typical 3-bedroom villa evening looks like: three air conditioners (800–1,200 W each running), a fridge and freezer (300 W), pool pump (750–1,100 W), water pressure pump (370–750 W), lighting (200–400 W LED), Wi-Fi, TV and chargers (150 W), and intermittent spikes from a kettle, microwave or hair dryer (up to 2,000 W each, briefly).
Running total for that villa: roughly 6–7 kW. If you stopped calculating here, you would buy an 8 kVA genset and regret it within a week. Here is why.
Step 2 — The Number Everyone Misses: Startup Surge
Motors do not start politely. An air-conditioner compressor draws roughly three times its running current for the first second or two; pool and well pumps behave the same. When PLN drops and your genset picks up the villa, several compressors may try to restart at the same moment — and that combined surge, not the steady evening load, is what your generator must survive without stalling or tripping.
The working rule we use: take your realistic running load, make sure the largest two or three motors can start on top of the rest, and keep 20–25% headroom above the result. Headroom is not waste — it is what stops the genset running at 100% (which shortens its life dramatically) and leaves room for the appliance you will inevitably add next year.
Typical Generator Sizes by Villa Type
| Property | Typical Load | Recommended Size |
|---|---|---|
| 1–2 BR villa, fans, no pool | 2–3 kW | 5–8 kVA |
| 2 BR villa, 2 AC, fridge, pumps | 4–5 kW | 10 kVA |
| 3–4 BR villa, 4–5 AC, pool pump | 6–8 kW | 12–15 kVA |
| Large villa, 5+ BR, full AC, outdoor kitchen | 10–14 kW | 20–25 kVA |
| Guesthouse, 8–10 rooms | 18–25 kW | 30–40 kVA |
| Small hotel / restaurant | 35–60 kW | 60–100 kVA |
These assume everything backed up. A cheaper strategy for large properties is a smaller genset feeding an "essentials" circuit — bedrooms' AC, fridges, pumps, lights, Wi-Fi — while the spa bathtub waits for PLN. We wire split circuits like this regularly during installation.
kVA vs kW — the 0.8 That Confuses Everyone
Generators are rated in kVA (apparent power), appliances in kW (real power). For typical villa loads the conversion is kW = kVA × 0.8. So a "15 kVA" genset delivers about 12 kW of real power. When a seller quotes you kVA and you compare it against your kW total without converting, you accidentally undersize by 20% — one of the most common mistakes in marketplace genset purchases.
Three Mistakes We Keep Seeing
Sizing to the MCB rating. Your 16,500 VA PLN connection is not your load — it is a ceiling. Most villas never approach it, and buying a genset to match it wastes serious money.
Ignoring the pool pump. It runs hours a day, it surges on start, and it is wired into a shed nobody thinks about. It belongs in the calculation.
Massive oversizing "to be safe". A 40 kVA unit carrying a 6 kW villa runs at 15% load forever — which causes wet stacking, fouled injectors and carbon buildup. Diesel engines want to work. Oversizing is not safety; it is slow damage you paid extra for.
Get the Calculation Done for You
Send us your appliance list — or just photos of your MCB panel and the appliances — and we will run the numbers and recommend a size in writing, free. Then compare our genset options and guide prices with anyone else's. The calculation stands either way.
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