Home Backup Generators: Why You Need One & How to Choose
home backup generators

Home Backup Generators: Why You Need One & How to Choose

When the power grid fails, your family, pets and home could be at risk. A prolonged power outage in the middle of winter could be disastrous and costly without a suitable home backup generator. In this post, we explore the reasons for having one and considerations needed before deciding what type to install.

Why You Need a Home Backup Generator

Here are a few of the many situations when you might need a home backup generator.

Your Home is Susceptible to Severe Weather Conditions

Some locations, especially in the Midwest, are prone to storms and heavy snowfall that cause frequent power outages. Other locations experience extreme temperatures and require air conditioning and heating for most of the year to maintain comfortable temperatures. Some power outages can last for days and, in these locations, cause severe disruption, emotional strain, and financial cost.

You Have a Well Pump or a Sump Pump

Your house may rely on an electric pump for pumping water from a well or borehole. If the power fails, you will have no water for drinking, washing, and flushing.

The sump pump normally keeps the basement dry. A power outage could result in the basement flooding, and this could result in damage to the property and the basement contents.

You Have a Large Refrigerator or Freezer

A power outage will cause any stored food to quickly spoil and go to waste. Not only have you lost the money the food cost, but you have also lost your stock of food when you most need it!

You Work From Home

You may be snowed in at home and unable to get to the office. With a backup generator, you will at least be able to email and video call in. This could save you losing valuable income.

Someone in Your Family Has Medical Needs That Require Power

Some people have a medical device that requires recharging or direct mains power. A power outage in this situation would be extremely dangerous.

Your Home is Frequently Vacant

You may be away from home for a significant part of the year. A home backup generator will help protect the house and maintain the security system while you are away.

What Size Home Backup Generator Do I Need?

The power output of generators is measured in watts. Watts are calculated by voltage (V) multiplied by current. Current is measured in amperes and labelled A or I. Therefore W = V x A. One thousand watts (W) equals one kilowatt (kW).

Generally, the higher the output power or wattage, the larger and more expensive the generator is. Buying an overpowered generator will just waste your money and lead to increased fuel and service costs. Buying an undersized generator will lead to the generator tripping out or being damaged as try to draw more power from it than it can produce. 

You need to determine what items in your house you want to power during an outage. This can be difficult and time-consuming. An electrician can help. There are items you need to keep supplied like the refrigerator, water pump, heating controls and lighting. Nowadays people usually consider the internet as essential.

Appliances with motors (washers and driers etc.) need more power at startup than when they are running. The label on the appliance will detail this. You should allow for this in your calculations. Cooking, heating, and cooling appliances are the most power greedy but also the most essential so be sure to include these in your calculations.

Make a list of the appliances you want to use during an outage. Look at the power consumption of each item. Add up all the items consumptions to find the total power you require. Now add 15% extra in case of error and to give you room to add extra items if you need to.

Estimated Generator Needs by House Size

  • A small house running essentials will need around 20 kW
  • A medium-size home will require around 35kW
  • A larger house with everything being used as normal may require 48kW or over

Different Types of Home Backup Generators

You also need to consider the style, cooling system, and generator design before you choose the correct one for the job. Home backup generators are either a portable generator or a fixed standby generator. Both types can be either air or liquid-cooled, and both types can be standard AC alternator type or inverter type. It sounds complicated, but we’ll explain the differences.

home standby generator for power outages

Portable Home Backup Generators

A portable generator is a multipurpose generator that is small enough to move. They’re commonly also used for camping or tailgate parties, and some people use them for job sites in remote off-grid areas. They are normally stored in the garage until needed, they have a small fuel tank and regularly need refueling (petroleum or diesel). The larger models are often noisy.

The power output is on the front or top, and you must plug in extension cables to run the power into your home. They sometimes have an electric start, but the smaller models have a manual starting pull cord.

Portable generators generally cost a lot less than the fixed standby generators. They are fine for short infrequent power outages but may be insufficient for running long-term in severe climates.

Standby Home Backup Generators

Home backup generators are also known as home emergency generators, whole house generators and standby generators. You will see them advertised under any of these names. They are all the same things. A permanently installed generator is situated inside or (more commonly) outside the house. Outside generators are usually cased and look a little like a large AC unit.

They are fueled by diesel, petroleum, propane (LPG) or mains natural gas. Home standby generators are installed permanently, can run on natural gas or propane, and kick in automatically during an outage. Most modern ones use natural gas. If they use other fuels, you need a large fuel tank close to the generator.

They are hard-wired into the house main switchboard (sometimes known as the consumer unit) via a transfer switch. Read the section on transfer switches, they are important.

Air-Cooled vs Liquid-Cooled

Whatever type of generator you have, the engine will need a cooling system. The small basic models are air-cooled by air traveling over metal fins on the engine casing. This system is simple and reliable with no moving parts to maintain or fail. They may overheat in hot weather and generally have a lower capacity than the liquid-cooled models.

Liquid-cooled generators have a liquid coolant like a car. They have a water jacket inside the engine with a pump that circulates the coolant through a radiator. The system is more complex than the air-cooled system and it needs to be maintained and serviced. Liquid-cooled generators can run almost indefinitely in all climates. Most large capacity generators are liquid-cooled.

Inverter Generators

Your grid electricity is stable at a set frequency and voltage. It has little harmonic distortion and is ideal for running sensitive electronics like computers, air conditioning and LED televisions. Normal generators are less stable and unsuitable for sensitive electronics.

The newer inverter type of generator uses a different process in generating the output power. It’s almost “pure” sinewave like the mains grid power. Inverter generators do not produce as much output power.

You should consider the output “total harmonic distortion” when buying a generator if you want to use sensitive electronics during a power outage. Look for less than 5% distortion in the output characteristics section of the technical specifications.

Generator Features to Consider

There are many other features to consider when buying a home backup generator. Think carefully about your exact needs and how frequently you are likely to use the generator.

What will happen if you are reliant on your generator for several days in extremely bad weather? Is your choice of generator suitable for this situation? After all, this is when you will need it most!

Fuel Type

A generator without fuel is just scrap metal in a power outage. Make sure you chose a generator that is easy to fuel. Think about the safety of storing fuel, what happens if the storage tank leaks? Are you concerned with fuel costs or is resupply an issue?


Most portable generators run on gasoline. It is easy to procure and is ideal for powering a generator to run a few lights and the refrigerator. Risks are around the storage of the fuel and its flammable nature. Gasoline also degrades over time when stored. Adding fuel stabilizer can prevent this.

Natural Gas

Natural gas is the ideal fuel for the larger home backup generators. It is cheap and supplied by a pipe. You will need a supply pipe already in place. It has lower emission levels than gasoline and diesel. Gas generators take some time to start up. There may be a short delay in the power output.


Propane is sometimes also known as liquid petroleum gas or LPG. It is stored under pressure as a liquid but turns into a gas when it is out of the gas tank. It is ideal for remote locations with no mains for natural gas.

Propane generators can be more expensive than other types. They are also generally lower capacity. You will need a gas storage tank close to the generator location. It is advisable to have the tank filled before the start of the cold season.


Diesel is a liquid fuel stored in a fuel tank next to the generator. It is easy to buy and delivered in a big truck with a filling hose. Diesel can run the largest of generators and is cost-effective. Diesel generators tend to be bigger and noisier than other types, but they produce more power. A good well-maintained tank and fuel pipe are essential.

Automatic Start

This is different from an electric start. An automatic start is often connected to the transfer switch. It will automatically start the generator if the transfer switch detects a mains power outage.

It saves you going outside in the cold and trying to find the generator start button in the dark, wet cold weather. It is also useful if you are away from home and the power cuts out. The generator will start automatically and protect your home contents and maintain security.

Enclosure Type

The enclosure is important. They protect the generator from the freezing temperatures, ingress of water and build-up of leaves and twigs around the engine. Plastic enclosures do not go rusty and are usually soundproofed and insulated. The plastic can be less robust than a metal enclosure. A metal case is more robust but will need regular maintenance to protect it from corrosion.

Smart Features

Many new generators have remote monitoring and even Bluetooth and Wi-Fi connections to your phone or computer. This lets you keep an eye on fuel and oil levels, maintenance requirements and fault diagnostics.

Fuel Efficiency 

Older generators can use a lot of fuel. Newer models are more efficient. Inverter and portable generators normally use less fuel than the larger home backup generators.

Service and Maintenance Costs

All generators require maintenance. It’s worth spending the time and money servicing and maintaining them before the start of the cold season. You can pay someone to do this for you as part of a maintenance contract.

Service costs (think filters, batteries, oil, pulley belts etc.) all have a cost. Consider the local availability of service parts. Some larger models have an automatic built-in maintenance feature that starts the generator periodically to keep the battery charged and the engine in working order.

Noise and Fumes

The portable and diesel generators are normally noisier than the large gas models. Diesel is renowned for creating smoke when the engine first starts. You do not want to upset your neighbors with a noisy, smoky old generator.


Look at the total package. What else do you get with the generator? Some have free installation, delivery, or extended warranty.


Check the details of the warranty.  It might be worth extending the warranty yearly on the more expensive models. Make sure you know what is and is not covered in the warranty.

Delivery and Installation

All generators are big and heavy. Even the portable types need decent trunk space for transport. All home backup generators will need specialist transport and lifting gear to unload and place the unit.

Think about the access route from the road to the proposed location. Is the installation also included? If not, you will need an electrician and possibly a plumber.

Federal and State Laws and Local Regulations

Investigate local building codes, property tax and safety inspection requirements. Failure to have the correct paperwork in place can affect your warranties, home insurance and result in a fine for non-permitted improvements.

Leading Manufacturers

Top generator manufacturers include:

  • Briggs and Stratton
  • Champion
  • Generac
  • Kohler

Each manufacturer has its specialties and varying qualities. Check out their websites for product details.

Transfer Switches

You should never plug a generator into your standard electrical outlet. You need a transfer switch. A transfer switch disconnects your house form the power grid and prevents the electricity from your generator flowing back out of your house and into the grid and the neighbors’ houses. It stops your generator electrocuting anyone working on the power lines.

You can have a manual transfer switch but there are little cost savings when compared to an automatic one. An automatic transfer switch (ATS) monitors the grid power. If it detects a voltage drop, it disconnects the grid power and starts the generator. It then connects the generator to your house circuits.

The ATS continues to monitor the grid power until it is reestablished. It then disconnects the generator, turns it off and reconnects the house to the power grid. You just sit in your chair for a few seconds until the power comes back on.

You will need a manual transfer switch if you use a portable generator and want to connect it to your house circuits. Transfer switches need to be installed by a qualified experienced electrician.

Backup Generator Safety

The main safety risks from generators are electrocution and carbon monoxide poisoning. Read more about using backup generators safely on Energy.gov.


All generators should be used per the manufacturers’ instructions. Always use a transfer switch if connecting the generator to your house hard-wired circuits. Home backup generators should be installed by qualified experienced electricians. The cables and generator should be maintained and checked regularly for worn or faulty components. A service engineer can help you with this.

Carbon Monoxide Poisoning

Carbon monoxide (CO) is produced by the incorrect combustion of fuel. It is a silent, invisible, and deadly. To prevent the buildup of CO, many new generators are equipped with a built-in sensor that shuts the generator down if CO is detected.

Even if your generator has this feature, you should still site your generator at least 20 feet away from your house. The exhaust should be directed away from windows, doors, and air conditioners. The generator should never be run in an enclosed space.


Generator maintenance is essential to ensure that it functions correctly when you most need it. The manufacturers provide basic maintenance details and procedures.

It’s a good idea to run the generator for 30 minutes each month to prevent parts corroding and seizing up. The fuel should be checked and stabilizer added if needed.

Service items such as filters, spark plugs, and lubricants need replacing periodically as set out in the instruction manual. The oil level should be checked each month. Keep the enclosure clean and free from leaves, twigs, insects, and vermin.


Your local electrical contractor will be able to install the generator. This ensures the generator is safe, robust, and compliant with local regulations.

You may need a plumber to connect the generator to the fuel source and supply and install a fuel tank. Large generators will require a concrete base.

Some systems include instructions for self-installation, but you will still need an electrician to check for compliance and safety. We recommend using an experienced local installation contractor who will have all the correct equipment and materials.


There are many different things to consider when choosing a home backup generator. Take your time with the process, the calculations, and decisions. Ask other people who already have one about their experiences. Talk to local suppliers and installation engineers for their recommendations.

A professionally installed and functioning generator gives you and your family great peace of mind, security, and protection when the power grid fails.

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