Best Generators for Home Backup: A Complete UK Guide

Power cuts can happen with very little warning. Bad weather, faults on the electricity network, local infrastructure problems and planned maintenance can all leave a property without mains electricity.

For many households, a short interruption is little more than an inconvenience. But when a power cut lasts several hours — or potentially longer — losing electricity can affect refrigeration, lighting, broadband, communications, heating controls, pumps, security systems and other important equipment.

A home backup generator provides an independent source of electricity, allowing essential appliances and equipment to continue operating until mains power is restored.

However, choosing the best generator for home backup isn't simply a case of buying the machine with the highest output.

You need to consider:

• How much power your essential appliances require
• Starting and surge loads
• Whether you want portable or permanent backup power
• Petrol versus diesel
• Noise levels
• Sensitive electronic equipment
• Fuel storage and runtime
• Generator positioning
• How the generator will be connected to the property

This guide explains the main options and helps you decide what type and size of generator is best for protecting your home during a power cut.

What Is a Home Backup Generator?

A home backup generator produces electricity independently of the National Grid.

Depending on the type of generator you choose, it can either power selected appliances directly or form part of a professionally installed backup electricity system.

There are two main approaches.

Portable Home Backup Generators

Portable generators are usually petrol, diesel, LPG or dual-fuel powered.

Rather than being permanently installed, they can be stored until required and positioned safely outdoors when a power cut occurs.

Portable generators can be an excellent choice if you only need to keep a limited number of essential appliances operating.

Typical applications include powering:

• Refrigerators
• Freezers
• Lighting
• Wi-Fi routers
• Laptops
• Mobile phone chargers
• Televisions
• Small appliances
• Heating controls
• Selected pumps

The biggest advantages are relatively low purchase cost, portability and flexibility.

Explore our range of portable petrol generators.

Standby Generators

A standby generator is a more permanent solution.

These systems are generally designed for properties where maintaining electricity is particularly important and can provide considerably greater power than smaller portable machines.

Depending on the installation, a standby generator can be connected through suitable changeover equipment so that selected circuits — or potentially much of the property — can receive generator power when mains electricity is unavailable.

Standby systems are particularly useful for larger homes, rural properties and locations that experience regular outages.

Electrical installation and changeover equipment should always be designed and installed by an appropriately qualified professional.

How Much Generator Power Does a House Need?

This is probably the most important question when choosing a generator.

There isn't one universal generator size that suits every house.

A small generator may comfortably keep a fridge, freezer, router and a few lights running, while a property requiring pumps, electric heating equipment or numerous appliances simultaneously may require significantly more power.

The starting point is identifying what you actually need to keep running during a power cut.

You don't necessarily need to power everything in the house.

For many homeowners, the priority list might be:

Appliance	Typical Backup Priority
Fridge	High
Freezer	High
Wi-Fi router	High
Basic lighting	High
Phone chargers	High
Boiler controls	High
Television	Medium
Kettle	Medium
Microwave	Medium
Washing machine	Low
Tumble dryer	Low
Electric oven	Low
Electric shower	Low

High-consumption electrical heating appliances can dramatically increase the size of generator required.

For that reason, an essential-load approach is often considerably more practical than attempting to reproduce the full electrical capacity of the property.

Running Watts vs Starting Watts

One of the biggest generator-sizing mistakes is looking only at an appliance's normal operating power.

Certain appliances contain electric motors or compressors that can require considerably more electricity for a short period when starting.

Common examples include:

• Refrigerators
• Freezers
• Water pumps
• Air-conditioning equipment
• Compressors
• Certain heating systems

This temporary additional demand is known as the starting, surge or peak load.

For example, your group of appliances might require 2,500 watts while operating normally but momentarily require considerably more when a compressor or pump starts.

Your generator therefore needs sufficient capacity to accommodate both the continuous load and these temporary peaks.

Always check the manufacturer's specifications for the equipment you intend to power rather than relying solely on generic appliance estimates.

What Size Generator Is Best for Home Backup?

As a broad way of thinking about generator sizes, home backup requirements can be divided into several categories.

1–2kW: Basic Emergency Backup

A small generator can be extremely useful during shorter outages.

It may be capable of powering a carefully selected combination of:

• Wi-Fi
• Phone chargers
• Laptops
• Lighting
• Television
• Smaller appliances

A compact inverter generator can be particularly attractive for this application because of its portability and suitability for electronic equipment.

For example, the Pramac PMi2000 provides a compact option for essential emergency power.

View the Pramac PMi2000 and our inverter generator range.

This level of generator is best viewed as an essential emergency power source, rather than a whole-house solution.

2–3.5kW: Essential Household Backup

Moving into the 2–3.5kW range gives you considerably more flexibility.

You may be able to operate a combination of equipment such as:

• Fridge
• Freezer
• Lighting
• Router
• Television
• Laptops
• Phone chargers
• Boiler controls
• Selected small appliances

The exact combination still depends on individual appliance consumption and starting requirements.

Models such as the Pramac PMi3000 and Pramac P3500i/O offer a useful middle ground for homeowners wanting considerably more emergency capacity without moving to a much larger conventional generator.

Browse inverter generators.

3.5–6kW: More Comprehensive Home Backup

For homeowners wanting to operate several household appliances simultaneously, a generator somewhere around this class can offer significantly greater flexibility.

Depending on the specific electrical loads involved, you might be able to support:

• Refrigeration
• Lighting
• Communications
• Boiler controls
• Kitchen appliances
• Home-office equipment
• Pumps
• Garage equipment
• Additional household circuits

This is often the point at which a professional assessment becomes increasingly worthwhile.

The more equipment you intend to operate simultaneously, the more important correct generator sizing becomes.

6kW and Above: Larger Home Backup Requirements

Larger properties or households wanting substantial backup capability may require a generator above 6kW.

Reasons for needing higher capacity could include:

• Multiple refrigerators or freezers
• Water pumps
• Larger heating systems
• Home offices
• Workshops
• Outbuildings
• Security systems
• Electric gates
• Larger domestic appliances
• Rural infrastructure

At this point, homeowners should seriously consider whether a properly installed standby generator is more appropriate than a portable machine.

Large backup systems should be designed around the property's actual electrical demand rather than purchasing purely according to a nominal generator output.

Inverter Generators for Home Backup

An inverter generator can be one of the best options for basic or medium-level emergency home power.

Inverter generators produce electronically regulated electrical output and are particularly popular where sensitive electronics need to be powered.

Typical equipment might include:

• Computers
• Laptops
• Televisions
• Broadband equipment
• Chargers
• Electronic controls
• Modern household electronics

They also tend to be compact compared with larger conventional generators, making them easier to store when not required.

Advantages of Inverter Generators

• Suitable for sensitive electronic equipment
• Compact
• Portable
• Generally quieter than large open-frame machines
• Efficient for lighter loads
• Excellent for essential emergency backup

Disadvantages of Inverter Generators

• Lower power capacity than many larger conventional or standby generators
• Cost per kilowatt can be higher
• Not normally intended as a complete whole-house backup system

For homeowners mainly concerned with keeping communications, refrigeration, lighting and electronics operating, an inverter generator deserves serious consideration.

Shop inverter generators.

Petrol Generators for Home Backup

Petrol generators remain one of the most popular forms of portable emergency power.

They're available in a huge range of outputs and are relatively straightforward to operate.

Advantages of Petrol Generators

• Wide choice of sizes
• Competitive purchase price
• Portable options available
• Excellent for occasional emergency use
• Petrol is widely available

For households experiencing only occasional power cuts, a petrol generator can make a lot of sense.

Things to Consider

Petrol needs to be stored and handled correctly.

You should also think about how long the generator may need to operate and how much fuel you can safely keep available.

For extended or frequent generator use, diesel may become more attractive.

Browse petrol generators.

Diesel Generators for Home Backup

Diesel generators are widely used where longer running periods, durability and larger power outputs are required.

They are particularly attractive for:

• Rural homes
• Farms
• Larger properties
• Regular outages
• Extended backup periods
• Permanently installed standby systems

Diesel generators are available from relatively compact machines through to large industrial generating sets.

Advantages of Diesel Generators

• Well suited to longer operating periods
• Strong choice of higher-output machines
• Robust engines
• Widely used for professional standby power
• Excellent option for larger backup installations

Potential Disadvantages

• Generally heavier than equivalent small petrol machines
• Higher initial purchase cost in many cases
• Noise can be a consideration without an acoustic enclosure

For residential environments, a silent diesel generator with an acoustic enclosure may therefore be preferable.

Browse diesel generators.

Silent Generators for Residential Areas

Generator noise is an important consideration that is sometimes overlooked until the machine is actually running.

An open-frame generator operating for several hours can become intrusive — particularly at night or in densely populated residential areas.

Silent and low-noise generators use enclosures and other noise-reduction measures to reduce operating sound.

A silent generator may cost more than an equivalent open-frame machine, but for regular home backup applications the improved noise characteristics can make a substantial difference.

View silent generators.

Portable Generator or Automatic Standby Generator?

Choosing between portable and permanent backup power largely comes down to how frequently you experience outages and how important uninterrupted electricity is.

Choose a Portable Generator If:

• Power cuts are relatively rare
• You only need essential appliances
• You have limited storage space
• You want a lower initial purchase cost
• You want a generator that can also be used elsewhere

Consider a Standby Generator If:

• Your property experiences frequent outages
• You live in a remote or rural location
• Electricity is essential for important equipment
• You require substantially more power
• You want a permanently installed system
• You want a more convenient backup solution

For some households, a quality portable generator provides everything required.

For others, a dedicated standby system is a much better long-term investment.

Can I Plug a Generator Directly Into My House?

You should never improvise a connection between a portable generator and your household electrical system.

In particular, never attempt to energise household wiring by connecting a generator through an ordinary wall socket.

Incorrect generator connections can create serious electrical hazards.

If you want a generator to supply circuits within your property, the system should be designed and installed by an appropriately qualified electrician using suitable changeover and protection equipment.

For straightforward portable-generator use, appliances may instead be connected in accordance with the generator manufacturer's instructions using appropriate cables and equipment.

Never Run a Generator Indoors

A petrol, diesel or LPG engine produces exhaust gases containing carbon monoxide.

Carbon monoxide is colourless and odourless and can be fatal.

A combustion-engine generator should therefore never be operated inside a house, garage, shed or other enclosed space simply because a door or window has been opened.

The generator must be positioned outside in a suitable location and operated in accordance with the manufacturer's safety instructions.

Never sacrifice safe positioning simply to make connecting the generator easier.

Don't Forget Carbon Monoxide Alarms

Homes using combustion appliances should already take carbon-monoxide safety seriously.

If you own a generator for emergency use, having functioning carbon-monoxide alarms provides another important layer of protection.

Check batteries regularly and replace alarms according to the manufacturer's recommended service life.

What Should You Power During a Power Cut?

Rather than trying to run every appliance, prioritise.

Priority 1 – Essentials

• Refrigeration
• Freezer
• Essential lighting
• Communications
• Medical equipment where applicable
• Heating controls
• Critical pumps

Priority 2 – Useful Equipment

• Television
• Computers
• Additional lighting
• Microwave
• Small kitchen appliances

Priority 3 – High-Power Non-Essentials

Where possible, avoid unnecessarily running:

• Electric showers
• Tumble dryers
• Large electric heaters
• Electric ovens
• High-powered workshop machinery

Reducing unnecessary demand means a smaller generator can support your genuinely important equipment.

Consider Your Heating System

Heating can create particular confusion when sizing a backup generator.

A gas- or oil-fired boiler might only require electricity for its controls, pumps and fans, meaning its electrical consumption can be relatively modest compared with the amount of heat it produces.

A completely electric heating system is very different.

Electric heaters, immersion heaters, electric boilers and electric showers can consume several kilowatts individually.

If maintaining electric heating during an outage is important, this requirement should be factored into the generator calculation from the beginning.

Don't Forget Your Water Supply

Rural properties sometimes rely on electric pumps for water supplies or drainage systems.

If your property uses a:

• Borehole pump
• Well pump
• Booster pump
• Sewage pump
• Sump pump

Then backup electricity may be considerably more important than simply keeping the television running.

Motors can also have significant starting demand, making accurate sizing particularly important.

Home Offices and Working From Home

With more households relying on internet connectivity and computers for work, even a relatively short power cut can be disruptive.

A modest inverter generator may provide sufficient emergency electricity for:

• Broadband router
• Laptop
• Monitor
• Mobile phone
• Lighting

While still leaving capacity for selected household essentials.

This is one reason inverter generators are particularly useful as compact home emergency power sources.

How Long Can a Home Generator Run?

Runtime depends on several factors:

• Generator model
• Fuel tank capacity
• Electrical load
• Engine efficiency
• Fuel type
• Operating conditions

Manufacturers generally provide runtime information at a specified percentage of rated load.

If extended outages are a concern, compare runtime, not simply maximum generator output.

A slightly larger generator running comfortably below its limit may sometimes provide a better practical solution than operating a smaller machine continually near maximum capacity.

Should You Choose a Generator Bigger Than You Need?

Some spare capacity is generally sensible.

Sizing a generator exactly to the calculated running load leaves little allowance for:

• Starting currents
• Additional appliances
• Future requirements
• Unexpected loads

However, massively oversizing a generator isn't necessarily the answer either.

Larger generators generally cost more to purchase, take up more space and can consume more fuel.

The goal is to select a machine with appropriate reserve capacity, not simply the largest generator available.

Home Generator Checklist

1. List Essential Equipment

Write down everything you absolutely need during a power cut.

2. Find the Power Consumption

Check the rating plate or manufacturer's documentation for each appliance.

3. Check Starting Requirements

Pay particular attention to equipment containing motors, pumps and compressors.

4. Calculate Simultaneous Demand

Work out which appliances are likely to operate at the same time.

5. Add Sensible Reserve Capacity

Avoid choosing a generator that will constantly operate at maximum output.

6. Choose Your Fuel

Compare petrol, diesel, LPG or dual-fuel options according to your expected use.

7. Consider Noise

This is particularly important in residential areas.

8. Decide How It Will Be Connected

Direct appliance connection and professionally installed household backup systems are very different applications.

9. Plan Safe Generator Positioning

Know where the generator will be operated before an emergency occurs.

10. Test Your Emergency Setup

Don't wait until the electricity goes off on a winter evening before learning how your backup equipment works.

Which Is the Best Generator for Home Backup?

There isn't one generator that is best for every home.

Instead, the right solution depends on the level of backup you require.

Best for Basic Emergency Power

A 1–2kW inverter generator can be ideal for communications, lighting and selected electronics.

Best for Essential Household Appliances

A 2–3.5kW inverter or petrol generator provides considerably greater flexibility and may support refrigeration, communications, lighting and selected household equipment.

Best for More Comprehensive Backup

A larger 4–6kW+ petrol or diesel generator may be appropriate where several appliances need to operate simultaneously.

Best for Regular or Extended Power Cuts

A diesel or dedicated standby generator becomes increasingly attractive where outages are frequent or substantial backup capacity is required.

Best Where Noise Matters

Consider a silent or enclosed generator, particularly in residential environments.

Prepare Before the Power Goes Off

A generator is most useful when you've planned your backup system before you actually need it.

Know:

• Which appliances you will power
• Their electrical requirements
• Where the generator will operate
• How equipment will connect
• Where your fuel will be stored safely
• How to start and stop the generator
• How often maintenance is required

Periodically checking and maintaining the generator is equally important.

A machine that hasn't been started for years isn't something you want to discover has a problem halfway through a prolonged power cut.

Find the Right Home Backup Generator

At Power Generators, we supply petrol, diesel, inverter, silent and standby power solutions for domestic, professional and industrial applications.

Whether you're looking for a compact inverter generator to keep your refrigerator, broadband and lighting operational or a larger generator for more comprehensive property backup, choosing the correct output is essential.

If you're unsure what generator you need, make a list of the equipment you want to operate and its power requirements.

Our team can help you compare suitable options and understand factors such as running power, starting load, fuel type and generator capacity.

Call 0800 222 9069 for generator sizing and product advice, Monday to Friday, 9:00am–5:00pm.

Browse all generators

Frequently Asked Questions

What size generator do I need to run a house?

It depends entirely on which appliances you want to operate. Running only a fridge, freezer, lights, internet equipment and boiler controls requires much less power than attempting to operate electric cooking, heating and other high-consumption appliances simultaneously.

Calculate the running and starting requirements of the equipment you intend to use before choosing your generator.

Is a 3kW generator enough for a house?

A generator around 3kW can provide useful emergency backup for a carefully managed selection of essential appliances. It generally shouldn't be considered a complete replacement for the property's mains electrical supply.

Is a 5kW generator enough for home backup?

For many properties, a generator in this region can provide substantial emergency capability when loads are carefully managed. Whether it is sufficient depends on your actual appliances and their starting requirements.

Is petrol or diesel better for a backup generator?

Petrol generators can be excellent for occasional emergency use and generally provide good value. Diesel generators become increasingly attractive for frequent use, extended running periods and larger standby applications.

Are inverter generators good for power cuts?

Yes. Inverter generators can be particularly useful for powering essential household electronics during a power cut, especially where computers, televisions, routers and other sensitive electronic equipment are involved.

Can I connect a generator directly to my consumer unit?

Any generator intended to supply household circuits should be connected using properly designed changeover and protection equipment installed by an appropriately qualified electrician. Never improvise a connection between a portable generator and household wiring.

Can I run a generator in my garage with the door open?

No. Engine-driven generators produce dangerous exhaust gases including carbon monoxide and should never be operated inside garages, homes or other enclosed spaces. Follow the manufacturer's outdoor positioning and ventilation requirements.

What is the quietest type of generator for home use?

Enclosed silent generators and many inverter generators are designed to reduce operating noise compared with conventional open-frame machines. Always compare the manufacturer's stated noise figures when selecting a model for a residential environment.