What Size Generator for a House? Your Complete Australian Guide
Power outages can strike unexpectedly, leaving your home in the dark and disrupting daily life. Choosing the right backup power solution is crucial, and it all starts with answering the fundamental question: what size generator for a house is suitable for your specific needs? Selecting a generator that's too small leaves essential appliances powerless, while one that's excessively large is inefficient and costly. This guide breaks down the key factors and calculation steps to ensure you find the perfect fit for your Australian home.
What Size Generator is Suitable for My Home? Key Factors
Several critical elements influence what size generator for a house you require. Understanding these ensures your backup power meets real-world demands.
Home Size
While not the sole determinant, the size of your home often correlates with the number and type of appliances. A large 4-bedroom house typically demands more power than a compact apartment. However, your specific appliance usage matters far more than square footage alone when determining what size generator for home backup you’ll need.
Electrical Load
This is the heart of generator sizing. It refers to the total wattage required by all the electrical devices you intend to run simultaneously during an outage. Crucially, you must account for both:
Running Watts (Rated Watts): The continuous power an appliance needs to operate.
Starting Watts (Surge Watts): The significant, temporary burst of power (often 2-3 times higher than running watts) required to start motors in devices like refrigerators, air conditioners, and pumps. Neglecting starting watts is a common cause of generator undersizing.
Emergency Needs
What are your absolute essentials during a blackout? Prioritise based on safety, health, and necessity. Common essentials include:
Refrigeration (food safety)
Basic lighting
Critical medical equipment (e.g., CPAP, oxygen concentrators)
Communication devices (phone charging, internet modem/router)
A few power points for essential electronics
Possibly a fan or small heater core unit, depending on climate
Future Expansion
Planning a pool? Installing ducted AC? Expecting an EV charger? Sizing up now beats buying a new generator later. What is the average size generator for a house in Australia? While typical homes use 5-8kVA systems, this varies wildly based on needs - your calculation matters more than average.
What Size Generator is Suitable for My Home? Calculation Steps
Determining what size generator for a house requires a systematic approach. Follow these steps for an accurate estimate:
List All Electrical Devices
Create a comprehensive inventory of every appliance and device you might want to power during an outage. Don't forget smaller items like phone chargers, Wi-Fi routers, and security systems. For each item, note:
The appliance name
Its Running Watts (often found on a nameplate or in the manual)
Its Starting Watts (if applicable, also found on nameplate/manual or via manufacturer specs). If unsure, a safe estimate is 2-3 times the running watts for motor-driven appliances.
Estimate the Maximum Power Consumption of All Devices Simultaneously
This involves two key calculations:
Total Running Watts: Sum the Running Watts of all devices you plan to run at the same time.
Highest Starting Watts: Identify the single appliance on your simultaneous-use list with the highest Starting Watts. Add this surge wattage to your Total Running Watts.
This sum (Total Running Watts + Highest Starting Watts) represents the Minimum Generator Capacity you need. It accounts for the base load plus the largest expected surge when everything is operating.
Consider Redundancy
While the above calculation gives you the minimum, adding a 10-20% buffer is highly recommended. This buffer:
Accounts for potential underestimates in wattage.
Provides headroom for adding a small, unexpected load.
Prevents the generator from constantly running at 100% capacity, improving efficiency and longevity.
Generator Size Estimate = (Total Running Watts + Highest Starting Watts) x 1.1 (or 1.2 for 20% buffer)
Choosing a Generator
Fuel Type: Common fuel options include petrol, diesel, and LPG, while battery or solar-powered portable power stations—such as the EcoFlow DELTA Pro 3 Solar Generator (PV400W), a home-backup solution with a 4 kWh base capacity (expandable up to 12 kWh), a 4,000W AC output, and support for PV400W solar charging plus optional extra batteries—are also gaining popularity for powering essential loads. When choosing a generator, consider both fuel availability and storage safety, especially during emergencies.
EcoFlow DELTA Pro 3 Solar Generator
Output: Match the calculated Generator Size Estimate to the generator's rated continuous output. Never choose a generator where your calculated load exceeds its continuous rating.
Portable vs. Standby: Portable generators require manual setup and connection (often via extension cords or a manual transfer switch). Standby generators are permanently installed, start automatically during an outage via an Automatic Transfer Switch (ATS), and are the ultimate home backup generator solution but come at a higher cost. Knowing how to safely prepare for power outage at home is vital, regardless of type.
Voltage: Australian homes typically use either 230V single-phase or 400V three-phase power. When determining what size generator for a house Australia requires—especially in rural or regional areas—it's crucial to know whether your home runs on single or three-phase power to ensure compatibility.
kVA vs. kW: Aussie generators list kVA. Convert: kW = kVA × 0.8. Need 4.2kW? Look for ≥5.25kVA. This answers what size kva generator to run a house – always base it on your buffered wattage calculation.
Why Should I Calculate the Power of My Home Generator Before Purchasing?
Skipping the calculation step is a recipe for problems:
Undersizing: The generator trips breakers or shuts down when overloaded, failing to power essential appliances. This defeats the purpose of having backup power and can damage both the generator and your appliances.
Oversizing: An excessively large generator runs inefficiently at low loads ("wet stacking" in diesel units), consumes more fuel than necessary, produces more emissions, and costs significantly more upfront. It's also often noisier than a properly sized unit.
Safety Hazards: Connecting too many devices to an undersized generator can overload circuits and create fire risks. Correct sizing ensures safe operation.
Cost Effectiveness: Calculating ensures you invest in the right-sized generator – not wasting money on excess capacity you don't need, nor facing the frustration and potential cost of replacing an undersized unit.
Investing the time upfront to size correctly ensures peace of mind when the grid goes down – and helps you choose the right home backup generator that won’t let you down in an emergency.
Can I Save Money Using a Solar Generator?
Yes — especially with strategic use. Here’s how:
Free Solar Charging: Pair it with panels for 100% fuel-free energy — zero ongoing petrol or diesel costs.
Minimal Operating Costs: No engine oil, stabilizers, or mechanical servicing — slashes upkeep expenses.
Indoor Use = No Extra Costs: Safe inside your home — skip pricey exhaust systems or outdoor enclosures.
Long-Term Value: Higher upfront cost, but quality units last years (thousands of cycles) — cheaper over time.
Prevent Blackout Losses: Run essentials (fridge, lights, comms) to avoid food spoilage or disruption costs.
For powering essentials and long-term resilience, a solar portable power station offers cleaner energy and often proves more economical than fuel generators.
Conclusion
Determining what size generator for a house you need isn't guesswork; it's a crucial calculation based on your specific electrical demands and priorities. By carefully listing your essential appliances, calculating both running and starting wattages, adding a sensible buffer, and understanding the different generator types and fuels, you can confidently select a generator that provides reliable, safe, and efficient backup power for your Australian home. For many homeowners seeking a robust solution, a correctly sized standby unit remains the best generator for home backup power for whole-house coverage.
FAQ
What size generator is suitable for a 200 square meter Australian home?
There's no single answer, as appliance usage varies drastically. However, a typical 200sqm Australian home with essentials (fridge, lights, fans, TV, modem, some power points) plus a ducted AC system might need at least 12-15kW (15-18.75kVA) or more. A home without ducted AC but with a split system might manage with 7-10kW (8.75-12.5kVA). Always conduct your own detailed calculation.
Can I connect my generator to my home wiring?
Yes, but ABSOLUTELY NOT via a simple power point ("suicide cord"). This is illegal and extremely dangerous, risking electrocution of utility workers and your family. You MUST use a properly installed, compliant Transfer Switch (manual or automatic) by a licensed electrician, isolating your home from the grid during generator use. This is a critical safety requirement under Australian standards (AS/NZS 3000).
What size generator do I need to run my refrigerator?
Most standard Australian household refrigerators require 150-300 running watts but can have a starting surge of 800-1200+ watts. Therefore, a generator with a minimum continuous rating of 1000-1500 watts is generally recommended to reliably start and run a single fridge, especially considering other potential small loads. Check your fridge's specific nameplate for accurate figures.