What Size House Will a 20kW Generator Run?
A 20kW generator runs the everyday load of almost any house, big or small. The catch is a large split system starting up, and a 20kVA badge on generators only means about 16kW. Here's how to check yours.
Floor area isn't the thing to size against. A small house running a big split system can need more than a large one with gas cooking and ceiling fans. What counts is what's switched on at once, and the biggest thing starting up.
The full method for every size is in our generator size guide. This one sticks to 20kW.
20kW and 20kVA Generator Ratings
kVA to kW at a 0.8 Power Factor
Most generators here are sold on kVA, and kVA isn't the same number as kW. Gentech lists its EP models at a 0.8 power factor. Multiply the kVA by 0.8 and you've got usable kW, so a 20kVA unit gives you about 16kW.
Genelite does the sum for you on its GH16000E, which lists 13kW from 16kVA.
A true 20kW works out to about 25kVA. That's bigger than anything in our generator range, and more than most houses will draw.
15kVA to 20kVA Generators in the Range
| Generator | Badge | Usable output | Outlets | Weight | Price |
|---|---|---|---|---|---|
| Gentech EP20000HSRE | 20kVA | about 16kW at 0.8pf | 2 x 32A, 1 x 15A | 160kg | $8,789 |
| Genelite GH16000E | 16kVA | 13kW | not listed | 140kg (25L tank) | from $7,839 |
| Gentech EP15000HSRE | 15kVA | about 12kW at 0.8pf | 2 x 15A | 160kg | $6,489 |
Specs and prices come from each product page, checked 14 September 2026. The EP20000HSRE page doesn't list a kW figure, so its 16kW uses the 0.8 power factor Gentech lists for its other EP models.
House Loads a 20kW Generator Runs
Fridges, Lighting, TV and Cooking
Queensland's Electrical Safety Office publishes typical appliance draws. A fridge or freezer runs on about 180W and a globe on 40W to 100W. A TV is up to 180W, a microwave up to 2,000W and a coffee maker up to 2,400W.
None of that worries 16kW. You could run two fridges, ten globes, the TV, the microwave, the coffee maker and an electric frypan together and still use less than half of it.
The same regulator says not to run a generator continuously above 80% of its rated capacity. On 16kW, that still leaves about 12.8kW for all-day loads.
Split System Aircon Start-Up
Aircon is where 20kVA runs out. The Queensland figures put a large split system at 6,000W running, and up to 30,000W to get it started. That's nearly double what a 20kVA generator makes.
A small window unit is gentler, at 1,200W running and up to 8,000W to start. Yours could sit anywhere between the two, so check the manual or ask your installer for its starting current. The guide to running an air conditioner on a generator goes further.
Worked Example With the Aircon Off
Here's a busy evening, using the Queensland figures plus the biggest start-up surge.
| Load | Running watts | Start-up watts |
|---|---|---|
| Two fridges | 360W | 1,800W for one |
| Ten globes | 1,000W | - |
| TV | 180W | - |
| Microwave | 2,000W | - |
| Coffee maker | 2,400W | - |
| Electric frypan | 1,300W | - |
| Total | 7,240W | 9,040W with a fridge starting |
That fits a 20kVA unit with room to spare. Add a small window aircon, though, and its 8,000W start takes the lot past 16kW. Turn the frypan and coffee maker off first and it fits again.
Connecting a 20kVA Generator to a House
15A and 32A Outlet Limits
A big badge is no use if the connection can't carry it. A 32A outlet at 230V tops out around 7.4kW. A 15A outlet sits at about 3.5kW to 3.6kW, depending on whether you count 230V or 240V.
The EP20000HSRE has two 32A outlets and a 15A. The EP15000HSRE only has 15A outlets, so you can't draw anything like its full output through its sockets. Ask your electrician how a big unit will connect to your switchboard before you buy it, not after.
Changeover Switch Installation
Never feed a house by plugging a generator into a power point. Queensland's regulator calls that backfeeding, and it's an electrocution risk for line crews and neighbours on the same transformer.
Connecting to house wiring is a job for a licensed electrician, with a changeover switch so only one supply feeds the house at a time. Energy Safe Victoria adds that a generator only ever runs outside, never indoors or in an enclosed space, because of carbon monoxide.
For the install side, read how to connect a generator to your house.
Smaller Generators for Most Houses
Think hard before buying 20kVA. The EP20000HSRE weighs 160kg, runs at 75 dBA at 7 metres and burns 6.88 litres an hour at 80% load. At early September 2026 petrol prices, that's about $14 an hour.
If your house connects through a 32A inlet, a 10kVA gives you everything that inlet can carry for a fraction of the price. The Hyundai HY10000LEK makes 8kW, has a 32A socket and costs $1,679.70. For fridges and lights through a 15A lead, a 5kVA is enough. Browse generators for home or the Gentech range.
If the big split system has to run, nothing portable we sell will start it. That's a conversation with an electrician about a much larger standby set.
So which one's for you? Tell us what you want running and we'll size it with you. Ring the store on 03 7056 6732, text 0476 330 590, or try the generator finder.
