What Size kVA Generator to Run a House: Complete Guide
Everything relies on electricity. An unexpected outage can seriously disrupt your household—your fridge stops running, air conditioning shuts off, and even the WiFi goes down. To avoid such situations, having a backup generator is essential.
What size kVA generator to run a house is the first question you should ask before making a purchase. A large generator is unnecessarily costly, while one that's too small may not meet your power needs.
No worries. This article will help you determine the right kVA generator for home use, along with essential knowledge and tips to guide your decision.
What’s the Difference Between kW and kVA in Generator Sizing?
When choosing the size of a generator, you’ll likely come across two units: kW and kVA, which are often confused with each other.
This section will explain what these two units mean and help you understand how they differ.
What is kVA?
kVA refers to apparent power, which measures the total amount of electrical energy used by your entire system. When evaluating a generator, kVA is typically used to express the total output capacity it can deliver under normal conditions.
What is kW?
kW stands for real power, meaning the actual usable power that a generator can supply to run appliances. This is the amount of electricity your home appliances actually consume to operate.
If your home electrical system runs at 100% efficiency, then kW = kVA.
But in reality, no system is perfectly efficient, so not all apparent power is converted into useful output.
The efficiency of an electrical system is measured by the power factor, a number between 0 and 1.
The formula to convert kW to kVA is:
kW = kVA × Power Factor
Most generators have a power factor of 0.8. For example, if a generator has a rated output of 10 kVA, the actual usable output would be approximately 8 kW.
What Size kVA Generator to Run a House Australia?
Having understood what kVA means, the next question is how many kVA to run a house. Different household sizes and power needs require different generator sizes, so be sure to consider your own situation carefully. Here’s a general range you can use as a reference:
Household Size | Recommended Generator Size (kVA) | Types of Generators | Notes |
Small Apartment / Single Occupant | 3-5 kVA | Small Power Generators | Basic lighting and small appliances |
Medium Household | 6-10 kVA | Medium Power Generators | Standard home appliances and air conditioning |
Large Household (For example, townhouses) | 10-15 kVA | High Power Generators | Includes heaters, washing machines, etc.; Multiple high-power appliances running simultaneously |
In addition, if you live in an area prone to natural disasters and frequent power outages, you may want to consider a generator that is slightly larger than the original standard.
How Do You Calculate the Total Power Needs of Your Home?
The generator sizes mentioned earlier are only general estimates. To accurately determine what size kVA generator to run a house in Australia, you'll need to calculate your total power needs. Here's how to do it:
Step 1: List Essential Appliances
Home generators are typically used to power essential appliances during power outages. So, list the appliances you want to keep running, such as Lighting, Air conditioner, Refrigerator, Heater, Computer, etc.
Step 2: Gather Starting and Running Power Data
You'll need to find both the starting and running watts of each appliance. These are usually found on the appliance nameplate or in the user manual.
Tips:
Starting wattage refers to the initial power needed when the appliance starts, often much higher than the running wattage.
Running wattage is the continuous power required to keep the appliance operating.
Step 3: Calculate the Total Power Requirements
Add up the running watts of all selected appliances to determine your total power demand.
Then, convert the result from watts to kilowatts (kW) by dividing by 1,000.
Do not forget the starting wattage, since your generator must be able to handle that surge.
Example:
If you want to power a refrigerator (180W), a heater (1500W), lights (240W), and a computer (350W) during an outage:
Total running wattage:
180W + 1500W + 240W + 350W = 2270W → 2.27kW
Highest starting wattage:
Heater → 3000W
Step 4: Convert to kVA
As mentioned earlier, electrical systems are not 100% efficient. To determine the generator size in kVA, divide your total power need (in kW) by the power factor (usually 0.8 for generators):
2.27kW÷0.8≈2.84kVA
In this example, your house would require a generator with at least 2.84 kVA capacity and a starting wattage capacity of no less than 3 kW to ensure reliable performance.
Why Picking the Right Generator Size Matters?
Choosing the right size generator for your home requires careful research and precise calculations, as a generator that doesn’t match your household's actual power needs can lead to serious risks.
When the generator is too large:
You may encounter underloading issues. This often happens when power demand is overestimated. An oversized generator consumes unnecessary fuel, increases maintenance costs, and operates below its optimal efficiency, potentially causing damage.
When the generator is too small:
Overloading becomes a risk. Running a generator beyond its capacity can lead to frequent breakdowns, reduce its lifespan, and fail to supply consistent power to your home, costing you even more in repairs.
To avoid these issues and manage your running costs wisely, it’s best to match the generator size to your actual household usage. It also helps to stay updated on average electricity prices in Australia so you can better plan for fuel and usage expenses.
Other Things to Consider When Buying a Generator
Aside from sizing and type, here are a few extra things that can affect your decision:
Noise Level
If you live in a quiet neighbourhood, the noise a generator makes can quickly become a deal-breaker. Solar generators are built to run more quietly than others, which makes them a better fit for areas with noise restrictions.
Maintenance Requirements
Generators need regular servicing to stay in good shape. Some require more frequent checks and oil changes, while others are designed for lower upkeep. If you'd rather not spend time on maintenance, look for models known for reliability and ease of use.
Safety Features
Modern generators often come with built-in protections like automatic shut-off, overload protection, and voltage regulation. These features not only help prevent damage to your appliances but also keep the generator itself from getting overloaded.
Fuel Options
Fuel type plays a big role in cost, performance, and even how easy your generator is to store and use:
Diesel generators are fuel-efficient and built for long-term use.
Propane works well in cold climates and stores well over time.
If you're looking for a cleaner, more sustainable option, consider a solar generator.
Solar generators don’t use traditional fuels at all. Instead, they store energy in large-capacity batteries or a portable power station and can be recharged via solar panels, AC outlets, or car chargers.
A standout choice here is the EcoFlow DELTA Pro Portable Power Station. It’s a powerful home backup option with an expandable capacity from 3.6kWh up to 25kWh and 3600W–7200W of AC output, enough to cover everything from lights and fridges to air conditioning. For anyone wanting a quiet, clean energy solution without sacrificing performance, it’s well worth considering.
EcoFlow DELTA Pro Portable Power Station
Conclusion
Based on your home area, and the specific appliances you need to power, you can estimate your total power needs and determine what size kVA generator to run a house.
For small to medium-sized homes in Australia, a generator under 10 kVA is usually sufficient. This capacity can handle daily appliances. However, if you're powering a large house or a villa, you may need a 10-15 kVA or even 20 kVA generator.
Once you've figured out the right size, don’t forget to consider other important factors when purchasing, such as the fuel type, safety features, and noise level. Careful planning ensures safer, more efficient energy use.
FAQs
Will a 10 kVA generator run a house?
Yes, for most ordinary Australian households, a 10 kVA generator is sufficient. It can power appliances such as refrigerators, water heaters, air conditioners, washing machines, lighting, televisions, and computers.
However, if you live in a large residence or plan to run multiple high-energy-consuming devices simultaneously, there may be a risk of overload.
Can I use a portable generator to power an entire home?
This depends on the size of your household. For medium to small-sized homes, a portable generator is suitable. Ensure it provides the required power output.
Products like the EcoFlow DELTA Pro are a good option. With a 3600W AC output (expandable up to 7200W), it can handle essential and high-demand appliances. It's a solar-compatible portable power station, making it a quieter, cleaner alternative to fuel-powered generators for whole-home backup during outages.
How much kVA for a 3-bedroom house?
For a 3-bedroom residence, a 6–8 kVA generator is recommended. The specific requirements also depend on your household's appliance usage.
If you're using appliances during peak hours or plan to use multiple high-power appliances simultaneously, it's advisable to choose a 10 kVA generator for safety. Also, don't forget to consider the starting power.