Home Backup Guide

When the power goes out, a generator can keep the essentials running and help your home stay comfortable, connected and secure.

But choosing a home backup generator isn't simply a case of buying the biggest model you can afford. A larger generator costs more to purchase, uses more fuel and can take up more space. Instead, the key is understanding what you actually need to power and choosing a generator with enough capacity to handle those requirements.

From working out your wattage requirements to choosing between petrol, diesel, dual fuel and inverter generators, here's what to look for when choosing a home backup generator.

What Is a Home Backup Generator?

A home backup generator provides an alternative source of electricity when your normal mains supply isn't available.

Depending on the generator and how it is installed, you can use it to power selected appliances and essential equipment, or potentially supply a larger proportion of your home's electrical system.

For many households, the most practical approach is to focus on essential loads rather than trying to run everything at once.

This could include:

  • Fridge or freezer

  • Boiler or heating controls

  • Lighting

  • Wi-Fi router

  • Television

  • Computers and other essential electronics

  • Security systems

  • Medical equipment

  • Selected kitchen appliances

  • Sump pumps or other essential pumps

The equipment you need to keep running will depend on your home and circumstances.

Step 1: Decide What You Need to Power

Before choosing a generator, make a list of the appliances and equipment you would want to use during a power cut.

Don't simply add up the wattage printed on each appliance. Some equipment, particularly appliances with motors or compressors, can require significantly more power when starting than they use during normal operation.

Fridges, freezers, pumps and some heating equipment are good examples.

It's therefore important to consider both running watts and starting watts when sizing your generator.

Essential Loads vs Non-Essential Loads

You may find that you don't actually need to power everything in your home.

For example, during a power cut you may consider these essential:

Appliance Priority
Fridge/freezer Essential
Lighting Essential
Wi-Fi router Essential
Heating controls Essential
Security system Essential
TV Useful
Laptop Useful
Microwave Useful
Kettle Useful
Washing machine Non-essential
Tumble dryer Non-essential
Electric oven Non-essential
Electric shower Usually high-demand

This approach can significantly reduce the generator capacity you need.

How Much Power Do You Need?

Once you've decided what you want to run, calculate the total wattage.

For example, if you wanted to run:

  • Fridge/freezer – 200W running

  • Lights – 100W

  • Wi-Fi router – 20W

  • TV – 100W

  • Laptop – 60W

Your normal running requirement would be around 480W.

However, you would still need to account for the starting requirements of appliances such as the fridge/freezer.

It's also important to consider which appliances might be used at the same time. You don't necessarily need enough generator capacity to power every appliance simultaneously if you can manage when higher-demand appliances are switched on.

Tip: Use a generator wattage calculator or your appliance ratings to build a realistic picture of your requirements before choosing your generator.

Use our wattage calculator to calculate a estimate of what you need.
Wattage Calculator

Don't Automatically Buy the Biggest Generator

More power isn't always better.

A generator that's significantly larger than your requirements can cost more to purchase, take up more storage space and consume more fuel.

Instead, aim for a generator that comfortably handles your expected load, including starting requirements.

You should also avoid regularly operating a generator at or beyond its rated capacity. Electrical equipment should be suitable for the supply available, and generator systems need to be correctly selected and installed for their intended use.

What Generator Type Should You Choose?

Once you've established how much power you need, the next decision is what type of generator is right for your home.

Inverter Generators

Inverter generators are a popular choice for home backup where portability, quieter operation and power quality are important.

They produce a stable electrical output and can be particularly well suited to sensitive electronic equipment.

They're also often more compact than traditional frame generators, making them easier to store when they're not needed.

Good for:

  • Smaller essential loads

  • Electronics

  • Home offices

  • Portable backup power

  • Quieter environments

Shop Inverter Generators

Conventional Generators

Traditional open-frame generators can provide substantial power and are often a practical option when you need to run larger loads.

They're generally less focused on portability and quiet operation, but can offer a straightforward solution where higher power output is the priority.

Good for:

  • Larger loads

  • Extended backup use

  • Workshops and worksites

  • Situations where portability and low noise aren't the main priorities

Shop Open-Frame Generators

Dual-Fuel Generators

Dual-fuel generators give you the flexibility to operate using two fuel sources, typically petrol and LPG.

This can be particularly useful for emergency backup because you have more than one fuel option available.

LPG can also be convenient for longer-term storage, while petrol can provide a readily available option when you need additional flexibility.

Good for:

  • Emergency preparedness

  • Longer backup periods

  • Added fuel flexibility

  • Homes that want an alternative to relying solely on petrol

Shop Dual Fuel Generators

Diesel Generators

Diesel generators are a strong option when you need reliable backup power for longer periods or have higher power requirements.

Diesel engines are well suited to sustained operation and demanding applications, which is why diesel generators are commonly used for commercial, industrial and larger backup power systems. For homes with significant electrical requirements, they can also provide a dependable solution during extended power outages.

Diesel generators are a good choice for:

  • Larger homes with higher power requirements

  • Extended power outages

  • Regular or frequent generator use

  • Applications where durability and long-term operation are priorities

  • Higher-power backup systems

However, diesel generators aren't necessarily the best choice for every home. They tend to be larger, heavier and more expensive than many petrol or inverter generators, and can produce more noise and vibration.

If you only need to keep a few essential appliances running during an occasional power cut, a smaller petrol or inverter generator may be a more practical solution.

Consider diesel if: you need higher power, expect longer running times or want a generator designed for demanding, regular use.

Consider another option if: portability, low noise, compact storage or a lower purchase price are your priorities.

Shop Diesel Generators

What Features Should You Look For?

Once you've narrowed down the generator type and required wattage, there are several features worth considering.

Electric Start

An electric-start generator can make getting backup power up and running much easier, particularly when you need it quickly.

Some models also include recoil starting as a backup.

Automatic Voltage Regulation

AVR helps regulate the generator's electrical output and can be useful when powering a variety of household equipment.

Low Oil Shutdown

A low-oil shutdown system can automatically stop the engine if the oil level becomes too low, helping protect the engine from damage.

CO Shutdown

Carbon monoxide protection can provide an additional safety feature on compatible generators.

However, this should never be treated as a substitute for safe generator placement. Petrol generators produce carbon monoxide and should never be operated indoors or in enclosed spaces. Guidance recommends positioning generators outdoors in well-ventilated areas where fumes cannot gather or enter buildings.

Remote Start

Remote starting can be useful if your generator is positioned outside and you want to start it without going out to the machine.

Wheel Kit

If you plan to move a larger generator around your property, wheels and a suitable frame can make a significant difference.

Multiple Fuel Options

If you're preparing for longer power cuts, dual-fuel capability can give you more flexibility over how you fuel the generator.

What You Probably Don't Need

It's easy to get distracted by specifications and features that sound impressive but don't necessarily make sense for your home.

You probably don't need:

A Huge Generator

If you only need to run a fridge, lights, Wi-Fi and a few essential appliances, you may not need a generator capable of powering your entire house.

Every Appliance Running at Once

You don't necessarily need to power your oven, washing machine, kettle, tumble dryer, TV and everything else simultaneously.

Prioritising essential loads can reduce the generator size you need.

Excessive Portability

If your generator is going to stay in one designated location, ultra-portable design may not be particularly important.

Features You'll Never Use

Electric start, remote start, dual fuel and other features can all be useful, but consider how you'll actually use the generator before paying extra for features that don't benefit your situation.

What Should You Avoid?

There are a few things you should be particularly careful about when choosing and using a home backup generator.

Avoid Buying Based on Peak Watts Alone

Peak or starting watts can make a generator look more powerful than it is during continuous operation.

Pay close attention to the rated/running wattage as well as the maximum or starting wattage.

Avoid Constant Overloading

Regularly exceeding the generator's rated capacity can put unnecessary strain on the engine and electrical system.

Leave yourself some headroom rather than selecting a generator that is only just powerful enough for your calculated load.

Avoid Running a Generator Indoors

This is one of the most important rules.

Never run a petrol or other combustion-engine generator inside your home, garage, shed or another enclosed space. Carbon monoxide is colourless and odourless and can build up to dangerous levels very quickly.

The generator should be positioned outdoors, away from doors, windows and other openings, with exhaust fumes able to disperse safely.

Avoid Connecting Directly to a Wall Socket

Never attempt to feed your home's electrical system by plugging a generator into a normal household socket.

If you want a generator to supply household circuits, the installation needs to be designed and connected correctly by a competent electrical professional, using the appropriate equipment and isolation arrangements.

Incorrect connections can create serious electrical hazards and can potentially energise circuits that are assumed to be switched off.

Do You Need a Transfer Switch?

If you're only powering individual appliances directly from a portable generator, you may not need a permanent transfer switch.

However, if you want your generator to supply selected household circuits, a properly installed transfer or changeover arrangement can provide a safer and more convenient solution.

This allows the generator supply and mains supply to be properly separated rather than relying on improvised connections.

For a permanently connected home backup system, speak to a qualified electrician about the appropriate installation for your property.

What About a Whole-Home Generator?

A whole-home backup system is designed to provide considerably more power and can potentially supply a much larger number of household circuits.

This can be useful for larger homes or households where keeping more equipment running during an outage is important.

However, it also means:

  • Higher generator capacity

  • Greater fuel consumption

  • More installation requirements

  • More space required

  • Higher purchase and installation costs

For many homes, a smaller generator supplying the essentials can provide a more practical balance between cost and capability.

Petrol vs Dual Fuel: Which Is Better?

There isn't one right answer for every household.

Petrol can be convenient because it is widely available and suitable for many portable generators.

Dual fuel gives you greater flexibility by allowing you to switch between fuel sources depending on availability and your requirements.

If emergency preparedness is your priority, having more than one fuel option can be a useful advantage.

Whichever fuel you choose, make sure it is stored safely and according to the relevant manufacturer and local requirements.

Think About Noise

A generator doesn't have to be running at full power all the time, and choosing an appropriately sized model can help avoid unnecessary fuel consumption and noise.

If you live in a residential area, consider the generator's stated noise level before buying. An inverter generator may be particularly attractive if quieter operation is important.

Remember that noise levels can vary depending on the load, operating conditions and where the generator is positioned.

Think About Fuel Consumption

Generator capacity isn't the only number worth looking at.

Two generators with similar power outputs can have different fuel consumption, so consider how long you expect the generator to run and how much fuel you'll need for an extended outage.

For emergency backup, fuel efficiency can make a significant difference over several hours or days of operation.

Don't Forget Maintenance

A generator that's been sitting unused for months still needs to be ready when you need it.

Regular maintenance should include checking:

  • Engine oil

  • Fuel condition

  • Air filter

  • Spark plug

  • Battery, where fitted

  • Fuel lines and connections

  • General condition of the generator

If you only use your generator during emergencies, periodically running it according to the manufacturer's instructions can help confirm that it starts and operates correctly.

Always follow the maintenance schedule provided for your specific model.

Home Backup Generator Checklist

Before choosing your generator, ask yourself:

  • What do I actually need to keep running?

  • How many watts do those appliances require?

  • What are their starting watt requirements?

  • Which appliances need to run simultaneously?

  • Do I need portable or fixed backup power?

  • Would an inverter generator suit my requirements?

  • Would dual fuel give me useful flexibility?

  • How important is low noise?

  • How long might I need to run the generator?

  • How much fuel can I safely store?

  • Where will I operate and store the generator?

  • Do I need a transfer/changeover system?

  • Will I need an electrician to connect it to my home's circuits?

  • What maintenance will the generator require?

The Bottom Line

Choosing a home backup generator doesn't have to be complicated.

Start with what matters most: what do you need to keep running when the power goes out?

Work out your running and starting wattage, prioritise your essential appliances and then choose a generator that comfortably meets those requirements.

Don't automatically choose the biggest generator available. Look at fuel consumption, noise, portability, fuel type, safety features and how the generator will actually be used.

And most importantly, think about installation and safe operation from the start. A generator is there to provide reliable backup power, but it needs to be correctly selected, positioned and operated to do so safely.

With the right generator and a little preparation, you'll be ready to keep the essentials running when the mains power goes down.