How much does it cost to install a backup generator?

Reviewed by Peter Thornton remodeling expert. Written by Fixr.com.

Power outages are inconvenient and dangerous, depending on your climate and the length of time your power is out. Without electricity, food spoils and goes to waste. During the very hot or cold months of the year, your home could reach dangerously hot or cold temperatures. If the power went out for days or weeks, you might have to move out until it is back on. Generators change this. They can power some or all your home until the electrical grid is restored. It can run your refrigerator, lights, and heating system at a minimum or power everything as if the grid never went down.

Generators come in many sizes and can be automatic standby models that turn on when needed or portable models you start. There can be a wide range of costs associated with purchasing a backup generator.
The national average cost is between $10,000 and $20,000 for a whole house generator. Most people spend around $15,000 on an 18kW generator capable of powering a 2,000 sq.ft. home with heating, cooling, hot water, lighting, and appliances. This project’s low cost is $900 for a 5kW portable backup generator that requires no additional installation to power your lights, refrigerator, and small appliances. The high cost is $25,000 for a 25kW generator capable of powering a 2,500 sq.ft. home with above-average power needs, including heating, cooling, large appliances, and car charging.

Backup Generator Installation Cost

House Generator Cost by Type

Generators for home use come in two basic categories - standby and portable. Both come in a range of sizes, which can power some or all your home in a power failure, but they operate differently. Standby generators are hands-off, and portable generators require personal oversight and set up. They also have very different costs.

Portable Generator

Portable generators cost between $200 and $6,000 on average. Portable generators come in many sizes, from small units that power small areas to larger units that power most of a home. Portable generators run off of gasoline or diesel fluid. The generator and fuel are usually stored outside, often in a container made for that purpose. They are turned on, started manually, and connect to your home via an extension cord. You must monitor the generator’s fuel level and refill it if you need to use it for an extended time.

Whole House Generator

A whole house or standby generator ranges from $2,000 to $20,000 on average. Standby generators are hardwired to your home. They sit on their own pad and are connected to a fuel source at all times. When the power from the grid is interrupted, the standby generator turns on automatically to power your home until the grid is reconnected. These generators use propane or natural gas and need a continuous supply. If you have propane tanks, your generator is connected directly to them. If you have natural gas, a line feeds your generator. These generators are larger and can often handle most or all your home’s load, depending on their size.

Backup Generator Cost by Size

Portable and standby generators come in several sizes. Portable generators are smaller than standby generators because they are often not designed to power the entire house. They can start under 2kW, but you need 5kW or more to power some of your home. Standby generators start at 7kW, but most homes need a 10kW to 12kW minimum, while homes with higher power needs may need larger generators.

What Size Generator Do You Need?

Ultimately, the generator’s size you need is determined by your typical daily power consumption. The process includes a visit to your home by the installation team before you purchase it. During this visit, they determine your system type, whether you have a well pump, your hot water heater’s power source, light count, and what large home appliances you have. You can choose the smaller size if your home is between sizes, which may mean using one large appliance at a time. Or, you can size up to use all appliances and lights.

You can get a basic understanding of the size you need by taking a survey of appliances, HVAC systems, lights, and outlets you need during an outage. These should all be labeled with power ratings. 1,000 watts equals 1 kilowatt. Energy-efficient lights use 6 watts each, while a hair dryer uses 2kW alone. Determine the size you need by adding up the watts you need during an outage.

Home Generator Price by Power Source

If you have a standby generator, you likely want to power it with natural gas, propane, or another readily available fuel that you can store in large tanks. Portable generators can be fueled by gasoline or diesel fuel, but you must purchase and bring smaller amounts home when you need the generator. Some portable generators are not limited to one fuel option and have a switch button that you can press to change from one fuel source to another.

If you want a portable generator without storing liquid fuel, you can use a solar generator. This works differently and charges batteries for later use.

Each generator has pros and cons to consider. For many, there is an overlap in costs for the generator. Fuel costs and availability are often the driving force behind your choice.

Gasoline Generator

Gasoline-powered generators cost between $500 and $2,000. Gas-powered generators are portable, not to be confused with standby natural gas-powered generators. Gasoline generators require you to purchase gasoline at a gas station and to store it until needed. Each generator uses gasoline differently, depending on the size and runtime. You must have sufficient gasoline on hand for prolonged outages. You also need to periodically refill your generator. Gasoline should not be stored inside.

Diesel Generator

A diesel generator ranges from $500 to $2,000. Diesel generators are also portable versions. You must purchase and store the diesel fuel until needed. Not all gas stations sell diesel, so ensure you have a nearby source. Like all portable generators, the fuel it uses is determined by the size and runtime. Prolonged outages may need extra fuel and frequent refueling. Diesel fuel should not be stored inside.

Propane Generator

Propane generators average $500 to $20,000, depending on whether they are portable or standby. Portable propane generators require you to purchase and store the propane until needed. Standby propane generators are connected directly to your home’s propane tank supply. As long as you have a sufficient supply in your propane tanks, the standby generator continues to draw. Since most propane delivery services can make deliveries even in a power outage, you are unlikely to run out of fuel with this generator. Do not store propane inside.

Solar Generator

Solar generators cost between $1,500 and $5,000. Solar generators work differently than other types. They are portable generators that run on batteries, and the batteries come as part of the package with the panels. You charge the batteries using solar panels before you need them. They only charge fully on sunny days, so do not wait until a storm to charge them. Once the batteries are charged, you can save them until needed. They hold their charge indefinitely, although brands may differ in their charge life. Then, you hook up your portable generator to the batteries. You can go several days or weeks without grid power, depending on the weather and battery capacity. Each battery’s capacity and the length of time it will power your generator varies by the brand and use. The batteries are safer to store than liquid propane, gasoline, or diesel fuel. There are also no ongoing fuel costs after the initial purchase, while other portable generators require frequent fuel purchases.

Natural Gas Generator

Natural gas generators range from $2,000 to $20,000, depending on the size. These are standby generators. They hook up to your home’s natural gas supply. If you have natural gas for cooking, heating, fireplaces, or other appliances, you can easily split off a line for a natural gas generator. This is one of the easiest generators to maintain because you do not need to worry about the fuel supply. Even propane standby generators must be watched to ensure another delivery is not needed before the power returns. With a natural gas generator, the fuel supply is constant.

Home Generator Cost by Type of Start

Home generators can also be classified in how they start. You can have an automatic generator, which turns on when it senses a disruption in your home’s power supply, or a manual start, which means you must turn the generator on.

All automatic generators have a manual start option, but all manual generators remain manual.

Generator Manual Start

Generators with a manual start only cost between $500 and $2,000. These are portable generators. They must be removed from their housing, connected to your home, and filled with fuel or connected to a battery to work. Some start by pushing a button, others have a pull cord. Some can be very physically demanding and difficult to start. If you are unsure if you can physically turn it on, opt for a push-button model or choose an automatic standby model.

Automatic Generator

Automatic generators average $2,000 to $20,000, depending on the size. Automatic generators are standby generators. They are always “on.” They typically run for about 10 minutes once a week for maintenance. They are permanently hardwired into your home’s electrical system. When they sense a drop in power, they start providing power to your home. They stop providing power when they sense the power returning. All automatic generators have a manual override. This way, you can turn them off at night or when away from home and then turn them back on again when you need them.

I always recommend an automatic transfer switch so, even if you are not home during a power outage, your generator will turn on within ten seconds. When you think about the items in your refrigerator, freezer, or even an A/C unit in a desert home, any delay in turning on backup power can cause significant damage and loss.

Peter Thornton, power services specialist.

Average Cost of Whole House Generators by Brand

You may have one or several brands of generators to choose from, depending on your area and available installers. Each brand has different costs, fuel types, sizes, and other considerations. Your fuel company may prefer some brands, so if you work with your fuel company for installation, they may recommend one over another. Others may be a better fit for your climate or the area you plan on installing them. However, most work similarly to one another once they are set up. Be sure to find out what the system costs and ongoing maintenance when deciding. Below are the average costs for each of the most popular brands of standby generators.

Briggs & Stratton Generator

Briggs & Stratton generators cost between $2,000 and $5,000. This company also makes smaller portable generators, starting at $700. Their standby generators run off of propane or natural gas. They come in sizes up to 15kW, which is sufficient for most homes. Their smaller portable generators run off gasoline. These costs do not include transfer switches or other parts necessary for installation.

Kohler Home Generators

Kohler generators average $2,000 to $6,000. Kohler is one of the first manufacturers of backup generators. Their plant was once a backup generator for large regions for nearly 2 decades, and they have some of the best-known generators in the country. Their sizing can be found in up to 15kW, which is sufficient for most homes. Their standby generators can run off of propane or natural gas.

Generac Home Generators

Generac home generators range from $2,000 to $30,000, depending on the size. Generac is one of the most popular and frequently installed residential standby generators. They have an incredible line of generators that can power large commercial spaces and smaller residential ones. You can easily find a generator that can power even the largest home with the heaviest power needs. Their generators can run on propane or natural gas. Costs do not include transfer switches or other parts necessary for installation.

Cummins Generator

The cost of a Cummins generator is between $3,000 and $15,000 on average. Cummins makes a very wide range of sizes for standby generators. Their generators can be powered by natural gas or propane. They pride themselves on producing generators of a higher quality and standard. Cummins generators are less likely to develop issues or suddenly stop working in the middle of an outage. Their costs do not include transfer switches or other parts necessary for installation.

Home Generator Installation Cost

Installation costs for a home generator start at around $5,000. Costs can go as high as $11,000 for very complex installations, but most people pay between $5,000 and $6,000.

The generator is seated on a small pad near the house, ideally situated close to your electrical panel. This pad can be concrete or filled with gravel. The generator is wired into your home’s panel, and a transfer switch is installed with it. The transfer switch senses interruptions in the power flow, which turns your system on and off.

A plumber is needed to connect your generator to your propane tanks or natural gas line. The process takes between 4 and 6 hours.

Whole House Generator Installation

The total cost range for installing a whole house generator is between $10,000 and $20,000, including all parts and labor. The labor portion is roughly $5,000, while parts like the transfer switch cost roughly $1,000, and other materials and the unit make up the difference. This includes delivery, setting the unit, and hooking it to its fuel supply and electrical panel. Most of this project’s work is done outside. The transfer switch is installed indoors. In most cases, a section of drywall must be removed to install the transfer switch below your electrical panel.

Generator Transfer Switch Installation

The transfer switch installation cost is roughly $2,700 to $3,700, including the transfer switch, electrical wiring, and labor. Labor makes up roughly $1,800 to $2,800, while the switch costs roughly $900. Installation is done indoors below your circuit breaker. The wall must be opened to install the transfer switch. You can have a box or door installed over it or tape and spackle over the drywall to conceal it. Mark the area and know that the wall must be opened again for future issues or maintenance.

Where Should a Whole House Generator Be Installed?

The exact location is likely determined by your home’s circuit panel location. The generator must be wired to the circuit panel and the transfer switch installed below it. It is usually located outside your home, a few feet away from the house, near the meter or circuit breaker. It may be moved a few feet in one direction or another to facilitate the fuel source hook up in some cases.

How Much Does it Cost to Run a Whole House Generator?

The cost depends on several things, including the generator size, how much power you draw at a given time, the fuel cost and type, and how long you run it at a time. The cost to run it is lower when you do not run your HVAC system other than in the coldest or hottest months. Your costs to run are also higher if you use a lot of power at one time rather than conserving energy.

Estimates range from $0 to $500 per year in energy costs, depending on the amount you use the generator, the fuel cost, and runtime.

How Long Can a Generator Run Continuously?

The length of time a generator can run continuously varies. Standby models are designed to continue running until the power is restored. This can mean running for days or weeks at a time. It can continue operating as long as there is a fuel source, and the unit is in good operating condition. Proper maintenance is required to ensure a standby model can continue functioning in this capacity.

Portable generators run as long as they have fuel. Check the fuel supply frequently and top it up as needed. Most people with portable models turn them off for stretches to conserve fuel or avoid running out in the middle of the night.

Some smaller generators have maximum run times. They vary by hours or days, so always check the owner’s manual for your model’s limitations.

Standby Generator Maintenance Costs

Standby generators are designed to run for a few minutes each week. During this time, they run self-diagnostics and can alert you to potential issues. Homeowners may have them serviced or pay for regular maintenance. Regular maintenance involves a service technician coming out on a scheduled basis.

In many cases, your generator alerts you when it requires maintenance. This could be through a standby light changing color or an error message. If you see one of these, have a technician service it. Otherwise, you can contract to have a technician come out a few times a year, during which they will make any necessary repairs or undertake regular maintenance, such as changing oil, cleaning parts, or replacing them. The average cost for maintenance is $200 to $500 a year, depending on the brand and how often the technician needs to come out.

Portable vs Standby Generators

Portable and standby generators are good options to keep lights and appliances running during a power outage. They work in different ways, however. A portable model requires you to take it out of storage, put fuel in it, and plug it into your home. You need to manually start the unit, which can take some effort, depending on the model. You need to keep an eye on the fuel level and refill the unit as needed. This means keeping a supply of fuel on hand. Depending on the fuel type, this can be dangerous because things like propane or gas should not be stored indoors. Therefore, you have the extra steps of retrieving and setting up the unit, as well as retrieving its fuel from a different source. People who rely on standby models often build or purchase a small storage shed just for this purpose to hold both the unit and the fuel right beside the house until it is needed. This can add to your initial costs.

Standby units are always “on.” They are hooked up to your home’s electrical supply and your natural gas line or propane tanks. They can sense a drop in power from the grid and automatically start to power your home. There is only about a 1 to 2-second delay between the grid going out and a standby generator starting. This means you will have a short power interruption when it turns on. It only lasts a second or two but can interrupt clocks, computers, and running appliances. When the unit senses the grid powering back on, it will turn itself off again with no further interruption in power.

Portable generators are often not large enough to power your entire home. You may need to choose what parts of your home you wish to power, such as the refrigerator and lights. Standby models are usually sized to power your whole home at once, including HVAC, large appliances, and lights.

Primarily due to the unit size and the added hook up and installation necessary for the standby unit, portable units are usually much less expensive to purchase, although they may take more effort to run long term.

Enhancement and Improvement Costs

Generator Battery

A battery generator can power a few small lights or appliances. You can pair one with a portable unit to charge phones and power other small electronics, freeing the portable unit to power your large appliances or HVAC system. They cost around $50 to $100.

Wireless Monitor

If you have a standby generator, you can purchase a wireless monitor to get status updates when you are away. If you are concerned about a power outage while away and want to know if your unit is running, a wireless monitor can alert you. They cost between $200 and $400.

Smart Load Manager

If your generator is not sized to handle the entire load, you can use a smart load manager to help. Smart load managers prioritize which parts of the home are powered by the unit and let you switch as needed. For example, if it cannot handle multiple large appliances at once, you can direct it to power the washer and dryer first, then switch to the stove to cook meals. A smart load manager costs between $150 and $300.

Additional Considerations and Costs

• Permits. Portable generators do not require permits to operate. Some areas may require permits for standby unit installations and inspections before use. Check with your local town or city hall for more information.
• Rental. In some areas, you can rent portable generators for short-term projects. Costs vary by rental but can be as low as $30 per day.
• Brownout. Most appliances use more watts at their start-up than they do running. If you do not factor this extra load into your calculations, you may overload or brownout your generator when you turn them on. When a brownout occurs, your lights may dim, then brighten, and large appliances like ovens and washing machines may stop work temporarily.
• Tax credits. There are no current tax credits for whole house generators, but this can change over time.
• Resale value. Whole house generators increase home value and make resale more attractive.
• Multiple units. When using portable generators, you can use more than one if you need additional load capacity.
• Noise. Whole house units are typically noisy, but their sound is less obvious indoors than outside. It can sound like a train going by if you are adjacent to the wall when the generator is on. In other areas of the home, it sounds closer to white noise.