What Size Generator Do You Need For A House?
Key takeaways:
- Small household backup power requirements can often be supported by generators in the 5kVA to 10kVA range
- Larger homes with higher power demands may require 20kVA generators or larger backup power systems
- Air conditioning is one of the biggest factors affecting generator sizing due to its high power requirements
- Startup loads should always be considered, as many appliances require significantly more power when starting than when running
- Choosing the correct generator size helps improve reliability, fuel efficiency, and overall performance during power outages
- Whole-house backup systems typically require larger generators than essential circuit backup solutions
- Understanding your home's total power requirements is the most important step when selecting a backup generator
Power outages can happen unexpectedly due to storms, network failures, maintenance work, or natural disasters.
A backup generator can help keep essential appliances running and reduce disruption during an outage. However, choosing the right generator size is critical. A generator that is too small may struggle to support your home's power requirements, while an oversized generator may increase costs unnecessarily.
The ideal generator size depends on what you want to power, how long you need backup power, and whether you're looking to support essential circuits or your entire home.
What Do You Want To Power?
The first step is deciding what equipment needs to operate during a power outage.
Some homeowners only want to keep essential appliances running.
Others want their entire property to continue operating normally.
Common household loads include:
- Refrigerators
- Freezers
- Lighting
- Internet equipment
- Televisions
- Air conditioning
- Hot water systems
- Pumps
- Kitchen appliances
- Home office equipment
Understanding your actual power requirements is the key to selecting the right generator.
If you're unsure how much power your appliances and equipment require, use our Generator Size Calculator to estimate your power needs before selecting a generator.
If you're unsure how generator sizing works, read our guide on kVA, kW, amps and watts.
Essential Circuits Only
Many homeowners focus on essential backup power rather than whole-house coverage.
This may include:
- Fridge and freezer
- Lighting
- Internet and Wi-Fi
- Phone charging
- Basic kitchen appliances
- Medical equipment
A smaller generator is often sufficient for these applications.
For example, many homes can support essential circuits using a 10kVA generator.
Learn more in our guide on what will a 10kVA generator run.
Partial House Backup
Some homeowners want to power additional equipment such as:
- Multiple rooms
- Entertainment systems
- Home office equipment
- Security systems
- Additional appliances
Depending on the total load, a larger generator may be required.
Many properties find a 20kVA generator offers a good balance between capacity and operating costs.
See our guide on what will a 20kVA generator run for practical examples.
Whole House Backup Power
Whole-house backup systems aim to keep most or all household functions operating during an outage.
This may include:
- Air conditioning
- Refrigeration
- Lighting
- Kitchen appliances
- Laundry equipment
- Home offices
- Pumps
- Security systems
Larger homes with multiple air conditioning units may require significantly larger generators.
In some situations, generators above 20kVA may be necessary depending on the property's total electrical demand.
Can A Generator Run Air Conditioning?
Air conditioning is one of the biggest factors affecting generator size.
While the running load may appear manageable, startup demand can be significantly higher.
Large ducted systems, multiple split systems, and commercial-grade air conditioning can quickly increase generator requirements.
Failing to account for startup loads is one of the most common generator sizing mistakes.
Single Phase Home Generators
Most Australian homes operate on single-phase power.
Single-phase generators are commonly used for:
- Residential backup power
- Small properties
- Essential circuit backup
- Home offices
Larger properties and specialised applications may require different solutions depending on their electrical setup.
Common Home Generator Sizing Mistakes
Only Calculating Running Loads
Many appliances require significantly more power when starting than when running normally.
Forgetting Future Requirements
Power requirements often increase over time as additional appliances and equipment are added.
Choosing The Cheapest Generator
The cheapest option is not always the most suitable.
Reliability, fuel efficiency, runtime, and support should also be considered.
Ignoring Fuel Consumption
Backup generators may operate for extended periods during outages.
Understanding fuel usage is important when estimating operating costs.
Our Diesel Generator Fuel Consumption Guide explains how generator size affects fuel consumption and runtime.
How Long Can A Generator Power A House?
Runtime depends on:
- Generator size
- Fuel tank capacity
- Load levels
- Fuel consumption
Some generators can operate for many hours before requiring refuelling.
Properties requiring extended backup power should consider both generator capacity and fuel storage requirements.
Understanding your household's typical electricity usage can help estimate fuel consumption and runtime requirements.
Generator Hire Vs Buying
The right solution depends on your circumstances.
Generator Hire
Generator hire may be suitable for:
- Temporary backup power
- Planned maintenance
- Emergency situations
- Short-term requirements
Benefits include:
- Lower upfront costs
- Access to modern equipment
- Flexible sizing
- Maintenance support
Generator Ownership
Purchasing a generator may be more suitable for:
- Permanent standby systems
- High-risk outage locations
- Critical home operations
- Long-term backup power planning
Many homeowners choose commercial generator sales solutions when installing permanent backup systems.
How To Choose The Right Generator For Your Home
The best generator should:
- Meet your power requirements
- Handle startup loads
- Operate efficiently
- Provide sufficient runtime
- Allow for future growth
If you're unsure which size generator is right for your property, our What Size Generator Do I Need? guide provides a broader overview of generator sizing considerations.
Need Help Choosing A Home Backup Generator?
SGH provides generator hire, backup power solutions, commercial generator sales, installation services, and ongoing support across Australia.
Whether you need temporary emergency power or a permanent standby generator, our team can help you identify the right solution for your property.
Explore our Generator Hire, Sales & Services Across Australia or contact SGH to discuss your backup power requirements.
FAQs
What size generator do I need for a house?
This depends on what you want to power. Essential circuits may require a smaller generator, while whole-house backup systems often need larger units.
Can a 10kVA generator power a house?
Many homes can run essential circuits such as refrigeration, lighting, internet equipment, and small appliances using a 10kVA generator.
Can a generator run air conditioning?
Yes, but air conditioning systems can create significant startup loads. Generator sizing should account for both running and startup power requirements.
What is the best generator for home backup power?
The best generator is one that matches your household's power requirements, runtime expectations, and budget.
Should I hire or buy a home backup generator?
Generator hire can be ideal for temporary or emergency situations, while purchasing may be more suitable for long-term standby power requirements. You can also read about this topic in more detail on out post about should i hire or buy a generator here.
