How Much Does a Whole House Generator Cost to Install? (2023)

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Highlights

• A whole-house generator has a typical cost range of $1,458 to $8,239 and a national average cost of $4,841.
• The main factors that can influence the total cost include the type and size of the generator, the power source, the type of start, and the cost of labor and permits.
• A homeowner might need to install a whole-house generator if they run a business from home, experience frequent extreme weather, or have a sump pump or crucial electric medical devices.
• A handy homeowner may be able to install a small generator by themselves, but for a large standby generator they’ll typically want to have a professional install the system.

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When lightning strikes too close to home and the power flickers then goes out, it can cause a variety of concerns: Will the meat in the freezer spoil? Will the children panic if they wake up without a night-light? Will critical medical equipment fail? What about the HVAC system? Power outages are inconvenient no matter how brief they are, but they can be expensive or even dangerous in some circumstances, especially if the outage is prolonged. The best home generators protect families and their homes by automatically sensing the power loss and triggering a backup power system. According to Angi and HomeAdvisor, the typical cost of a whole-home generator is $1,458 to $8,239, with homeowners paying $4,841 on average.

Many people envision buying Home Depot generators when they consider backup power options. That gasoline-powered portable block on wheels that generates power (along with a whole lot of noise) is what shoppers see on sale during storm season. While the best portable generators work for emergency use during storms or time spent in a camper, a whole-house generator is a different kind of appliance.

Once limited to hospitals and government buildings, large generators are now an option available to many homeowners. While there are many generator uses, generators are especially popular in areas regularly threatened with heavy snowfall or high winds or in remote areas where the power lines are less reliable. The average whole-house generator cost nationwide is $4,841, but several options can raise or lower this cost based on individual homes’ needs. It’s essential for homeowners to understand the possibilities and to be familiar with the terminology before shopping in order to develop a realistic budget and decide which whole-house generator is the best fit for them.

Whether homeowners are operating a small portable gas generator or a massive standby generator for a whole home, the same precautions will need to be taken. Homeowners should never, under any circumstances, operate a generator inside a home or garage—even with the doors and windows open. Carbon monoxide is a lethal gas that can accumulate quickly, and by the time it’s clear that something is wrong, it may be too late. Portable generators belong outside, with the doors and windows nearby closed tightly. Home generators are safe and beneficial instruments, but homeowners must take precautions to ensure proper ventilation and air exchange in order to keep a home warm and bright while also protecting the people living in it.

Factors in Calculating Whole-House Generator Cost

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The demand for whole-house generators varies based on weather conditions, market, and region. It’s not uncommon to see the cost of all generators spike after an extended power outage caused by a snowstorm or hurricane, for example, as people who have been inconvenienced by the outage rush to stores to protect themselves from future events. In addition, there are several variables for homeowners to keep in mind, and these choices can affect the overall cost of a home generator by thousands of dollars. Homeowners will want to note the size of their house and electrical panel so they don’t buy more power than is necessary. Other options may be nonnegotiable.

Generator Type

There are three kinds of generators for a house: portable, partial, and whole-house. Portable generators are the cheapest option and can support one or more important systems such as air conditioning in the event of a power outage. Portable generators run on propane, diesel, or gas, so they cannot be used inside the home; they can, however, be placed in any outdoor location. Partial and whole-house generators (also called standby generators) are larger, permanent installations that sit outside of the home and are hardwired into the electrical system. As can be expected, the cost of a whole-house generator is significantly higher than the cost of a portable unit.

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Generator Size

Standby generators come in sizes ranging in power from 9 to 48 kilowatts (kW) and cost from $500 to $18,000. A standby generator with about 25 kW can power a 2,500-square-foot home. Another option is the portable generator, which can range in power from about 1 to 7.5 kW. These are less expensive but are limited to powering a couple of lights and appliances—they’re generators that will keep the most basic electrical items running but aren’t backup power for the whole home. These smaller support generators cost between $500 and $2,000. Some common generator sizes and their average costs are below.

Generator Brand

When homeowners are selecting a partial or whole-house generator, there is a wide variety of brands to choose from. Size options, as well as prices, may vary between these brands, so homeowners will want to find the unit that best fits their needs and budget. Below are the starting costs for some of the best generator brands on the market.

Fuel Source

Generators operate on a variety of fuel sources. This won’t affect the purchase price but will affect the cost of purchasing and storing the fuel and the total cost of running the generator. Generators can be powered by gasoline, liquid propane, diesel fuel, and natural gas. Some solar-powered generators have entered the market, but they’re a bit less common.

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Start Type

Every generator, whether portable or standby, has a manual start option. In most cases, portable generators have a pull cord similar to a lawn mower starter, but others have an electrical switch. These manual generators typically cost between $500 and $2,000. Fixed standby generators, wired into the home’s electrical panel, will sense the power interruption to the house and automatically turn on, ensuring minimal loss of power and limited potential damage to the home and its systems. Generators with this added convenience come at a higher price point of $2,000 to $30,000. Automatic generators also include a manual start switch as a backup.

Concrete Pad Installation

Before going ahead with the whole-home generator installation, homeowners will want to remember that the unit will need a permanent resting spot. The most common installation method is on a poured concrete pad, which offers reduced vibration and increased airflow and prevents pooling water from damaging or rusting the underside of the unit. The pad needs to be strong, solid, and level. Professional installation will run between $50 to $75 per square foot, including site preparation and concrete pouring.

Labor

Installing a whole-house generator is not a one-and-done kind of job. A contractor may itemize the whole-house generator installation costs, including the charges for site preparation, labor, fuel storage tank, upgrades to the electrical panel, and any additional materials. Some contractors may have a flat rate for the entire installation. In these cases, it’s essential for a homeowner to fully understand what the installation includes. On average, installation cost ranges from $1,500 to $5,000.

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Transfer Switch Installation

For a standby generator that will power an entire home, an electrician will need to install a transfer switch, which connects the generator to the circuit board in the home and allows it to run power through existing circuits. These take 3 to 4 hours to install (around $1,200 in labor costs), and the switches can be manual (which the homeowner will need to activate) or automated (which will sense the power cut and smoothly self-start to ensure continuous power).

Permits

An installed generator hooks into a home’s electrical system, so a permit is required to ensure that the work is done correctly and safely. In addition, most municipalities will require a permit to pour a concrete pad to support the generator. These permits average between $50 and $200 apiece.

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Additional Costs and Considerations

Along with the cost of installation, the cost of the generator itself is high, but buying a whole-house generator can save money in the long run by allowing homeowners to remain in their homes during a lengthy power cut. After the purchase and installation, however, there are still some costs for homeowners to keep in mind.

Maintenance Costs

Standby generators automatically run for just a few minutes several times a week. This keeps the engine oiled and running smoothly and allows the generator to run diagnostics and notify the homeowner if there’s a problem that needs to be addressed. This doesn’t cost anything—but it does mean that the generator needs to be continuously fueled. It’s wise for a homeowner to schedule maintenance service by a technician periodically, usually just before the season when backup power is most likely to be needed. Homeowners can expect to pay between $80 and $300 for this yearly service. They may also want to consider investing in one of the best generator covers to protect the unit from the elements and extend its lifetime.

Running Costs

The generator itself can’t do its job without the appropriate fuel. For an installed generator, this usually means connecting the generator to a natural gas line or sizable liquid propane tank. The daily cost to run a 21 kW generator on natural gas is about $90. If a tank is being used, it will need to be kept filled, and the costs for this will depend on the gas provider. Running a 20 kW unit on propane for a day costs about $220. Using diesel for a generator of the same size costs $175 per day on average. Portable units need to be filled as they are used; both gasoline and diesel fuel have short shelf lives and will lose effectiveness if left sitting in a tank (this could potentially damage the tank and sensors as well). For reference, running a 5 kW portable home generator costs $100 per day. Homeowners will want to price out how much gas to keep on hand and change the tank out periodically to gauge the cost of use.

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Enhancements and Improvements

Several potential upgrades will make a generator more efficient. A wireless monitor provides access to the status of the generator. If the homeowner is away from home and there’s a power outage, they can make sure that the generator has kicked on. These monitors cost between $200 and $400. A smart load manager can help create different zones in the home and switch the power between them. This option can make an undersize (and less expensive) generator work in a larger house and costs approximately $150 to $300.

Electrical Upgrades

An electrical subpanel redirects power from a home’s main panel to another part of the property. This can prevent the main panel from overloading. If a home does not already have a subpanel, or it has one that is older than 25 years, an electrician may recommend adding a new subpanel before installing a generator. This can cost between $400 and $1,750. In other cases, a dedicated circuit may need to be installed before the generator. This may be the case if the home’s electrical panel is not easily accessible from the generator’s location. It costs about $550 to $1,000 to put in a dedicated circuit.

Battery Backup Installation

Battery backup is one power source option for standby generators. These units draw power either from the home’s panel or from a solar source to be stored until it is needed. These units can cost $10,000 to $25,000, plus an additional $800 to $1,500 for installation.

Whole-House vs. Partial Generator

Whole-house generators are the most expensive units on the market because they can power an entire home. They are also typically standby generators, meaning they will run automatically in the event of a power outage. While prices can vary based on size, on average a whole-home generator costs $17,000. A partial generator is able to support a home’s most essential power needs, such as kitchen appliances, but cannot produce enough power for the entire home. By contrast, these units cost between $3,000 and $12,000.

Standby vs. Backup Generator

A standby generator will kick on as soon as it detects a power failure. This is in contrast to manual generators, which must be turned on by the homeowner. A standby generator may cost anywhere from $5,000 to $25,000. “Backup generator” is a general term that refers to any home generator that acts as a backup to the home’s main power source. Home backup generators may be standby, manual, or portable, and costs can vary greatly.

Standby vs. Portable Generator

Standby generators are permanent additions to a home or business that can take over powering essential functions until the main system is back up and running. Standby generators cost around $17,000 on average, but there may be additional costs with installation, such as for pouring a concrete pad for the unit or adding an electrical subpanel. Homeowners who anticipate needing backup power often may want to consider installing one of the best standby generators. Portable generators have a capacity of only up to 10 kW; however, they are a more affordable option at $2,000 to $10,000 and can provide peace of mind for homeowners who are not at a high risk of power failure. They are also easier and less costly to install, since they are not wired to the home’s electrical system.

Whole-House Generator Cost by Fuel Type

The type of fuel a generator uses affects the total cost in two ways. First, the price of the unit itself is affected by the fuel type. Second, the cost of running the generator will vary based on the cost of that particular fuel at the time that the generator is needed.

Diesel

Costing between $3,000 and $20,000, diesel generators are usually larger machines that can power a whole house. Exceptionally efficient, diesel-powered generators are more cost effective the larger they get.

Gasoline

Gasoline generators are usually the least expensive option. They are simple engines that use gasoline to produce electricity. Gasoline is readily available in most parts of the country, making this a popular choice. However, it’s important for homeowners to note that gasoline has a short lifespan and may need to be discarded at a cost when it has gotten too old. Gas-powered generators are smaller, less powerful options that are portable and require a manual start. They cost between $500 and $3,000.

Liquid Propane

Clean-burning liquid propane (LP) can be stored indefinitely if it’s stored properly. It can be a great option for homeowners who already have a liquid propane contract and a large tank to use with other appliances, such as a dryer or stove. An LP generator can be a small portable generator or a larger standby unit and cost between $600 and $21,000. Homeowners who don’t already have a large tank or a contractor will need to store many smaller gas cans to make sure they have power when they need it. At that point, LP generators are not as cost effective as other models.

Natural Gas

Generators powered by natural gas are more expensive at the time of purchase than gasoline generators, averaging between $2,000 and $21,000; however, there’s little fuel waste because the generator uses fuel drawn directly from the utility when it needs it. Homeowners are advised to keep in mind that while natural gas prices are often a bit lower than gasoline, a natural gas generator uses more gas than other types.

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Solar

Solar generators are also modestly sized portable generators simply because the technology needed to convert and store large amounts of power would require too much space. They are sustainable and not dependent on petroleum-based fuel, which is a significant environmental benefit but may be limited in power generation by the stormy weather that caused the outage to begin with. This technology is still in development and will likely become more efficient and streamlined as technology advances. Solar generators cost between $2,000 and $25,000, with most costing at least $10,000.

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Do I Need a Whole-House Generator?

Portable generators are less expensive and take up less space on a property than whole-house generators—and they can be loaned to friends and family if they need a power boost. And really, how often will the whole house need to run on backup power for days on end? For many homeowners, a portable generator is a reasonable investment for those rare moments when it’s required. In some circumstances, though, there are clear benefits to choosing a whole-home generator.

Home Business

For those who work or run a business from home, a whole-house generator can have the power back up and running in less than a minute after an outage. Without a generator, an ill-timed thunderstorm can cut off connectivity moments before a big meeting or client consultation. And relying on a portable means quickly getting outside to fuel and start up the portable (and running several feet of extension cords) while wearing work clothes and trying not to panic. A standby generator can make the difference between a deal made and a deal lost.

Extreme Weather Conditions

While many areas that live under the threat of tornadoes, earthquakes, hurricanes, derechos, and blizzards have moved toward underground power lines, most of the country’s power grid transmission is still dependent on wires strung carefully between poles. For homeowners who live in an area that regularly loses power due to weather conditions, a whole-house generator can mean spending less time worrying about whether or not the freezer was out of power long enough to let the meat go bad.

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Sump Pump

Homeowners who regularly experience fast, torrential rains, who live in a floodplain, or just have poor drainage around their home probably also have a sump pump. Sump pumps are an automated way to keep basements and low-lying areas of the home from accumulating water or flooding—at least if they have power. When the storm bringing a flood to the basement has also knocked out the power, a sump pump can’t help, and there is likely to be water damage in the basement and potentially structural damage to the home. A sump pump will need to be supported by a standby generator that will make sure the sump pump can do its job.

Crucial Electric Medical Devices

Breathing machines, respirators, home dialysis machines, power-assistive devices—homeowners who have one (or more) of these devices in their home know that power loss is a matter of life and death. There’s no time to pull out and fire up the portable: Immediate power is essential for medical devices to continue working. A whole-house generator, even a smaller one that only powers the medical devices, is crucial in this case.

What Size Whole-House Generator Do I Need?

Generators are labeled by size using the total number of kilowatts (kW) they can produce. There’s no sense in purchasing a generator with more power than is necessary, and choosing one that is significantly underpowered will be frustrating and feel like a waste of money. So what size generator do you need? Whole-house generator sizing will depend both on the size of the home and the residents’ energy needs. A 14 to 18 kW unit is often sufficient for powering essential functions in a small or medium-size home. A 26 to 32 kW unit is a big enough generator for a whole house with average energy needs. Larger homes that require a lot of power may need a 45 to 48 kW generator. The best way to determine the correctly sized generator for a house is for an installer to assess the home and the property. They can take stock of what the generator will need to cover and recommend size and type. It’s a good idea to collect several of these estimates.

Some homeowners prefer to estimate the costs themselves, whether to check the accuracy of a contractor’s bid or to choose the size on their own. Homeowners taking this approach will need to look at each item that will need to be plugged in while the generator is in use, including appliances, electronics, the water heater, HVAC systems, and the garage door. They will then need to mark each one with a label that shows how many watts the item uses.

The formula will look like this:

Total number of watts needed/1000 = number of kilowatts needed to power the home

The number of kilowatts is the guide: If it’s between two sizes of generators, homeowners may want to size up for comfort or size down and engage in strategic power use during an outage to save a few dollars.

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Whole-House Generator Installation: DIY vs. Hiring a Professional

If a portable generator is adequate, most homeowners can prepare the generator before an anticipated outage or get it running pretty quickly after an unanticipated one. However, a larger standby or backup generator is not a DIY installation. For starters, there are many regulations concerning where the generator may be located in relation to the home, other structures such as garages, and neighboring properties. Permits must be obtained before work can start, and the power provider will need to be notified. Homeowners will also need to make note of local requirements for gas connections. Additionally, generators are large and heavy and must sit on a concrete pad. They require advanced electrical work and possibly fuel line installation. Homeowners will want to remember that these units are complex and that making mistakes with a home generator can result in electrical shock or carbon monoxide exposure. Pouring the pad incorrectly, installing the connections improperly, or even pulling the wrong permits can be dangerous and costly, so the best option is for a homeowner to hire a professional to make sure the installation is completed smoothly.

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How to Save Money on Whole-House Generator Cost

Saving money on a generator purchase is primarily a matter of being patient, considering the timing, and knowing exactly what you need.

• Shop around for estimates. Collect several estimates, both on the size of the generator and the installation cost.
• Use fewer contractors. Choose a contractor who can perform all the needed tasks (concrete pouring, gas plumbing, and electrical) to save on subcontractor fees.
• Plan installation in the off-season. Install at an off time of year when power losses are less frequent in your area.
• Plan ahead. Don’t run out and buy a generator right after the first big storm, when the item, material, and labor costs are highest.
• Take on some of the prep work. Ask if there’s any work you can do ahead of time, such as preparing the site or pulling the permits yourself.
• Buy the right size generator. Make sure that you don’t need to size up or down before you buy.

Questions to Ask About Whole-House Generator Installation

It’s important for a homeowner to ask a potential contractor some questions before hiring them. As always, homeowners will want to ask about licensing and insurance (and the licensing and insurance of any subcontractors or workers who are expected to take part in the project). It’s also a good idea to ask for and check references. The following are some additional questions specific to generator installations that homeowners can ask.

• What unexpected costs might crop up during the installation?
• Which parts of the job will you handle, and which will you subcontract?
• What is the payment schedule?
• Why do you think this generator is the correct size for my home? Should I consider going up or down a size?
• How much will it cost to run the generator?
• How long can the unit continuously run?
• Why is this the best site for my generator?
• What maintenance do you expect I’ll need? Do you provide maintenance through a contract or individual appointments?
• How long will the unit last until it needs to be replaced?
• After installation, will you show me how to use the generator properly?

FAQs

Before having a whole-house generator installed, there are quite a few decisions for a homeowner to make. Decisions about size, type, fuel, and other elements will help homeowners determine what the best whole-home generator option is for their home. These can start to feel like too many choices, so just ahead are a few of the questions that are most often asked about this topic, along with answers for getting started.

Q. How much does it cost to run a whole-house generator?

This depends on the size of the home, the size of the generator, and the number of items that need to be powered. On average, a small portable generator costs about $30 to $70 per day to run, while a 15 to 20 kW generator that powers the entire home will cost about $50 to $150 per day. Homeowners will also want to factor in fuel costs, which are dependent on the type of fuel, and could be as much as $30 per day in gasoline alone.

Q. What do I need to know about generator maintenance after the installation?

Generators only operate outdoors, so it’s not surprising that they’ll need a little maintenance periodically. At the cost of $80 to $300, annual maintenance will keep a generator in excellent condition. A standby generator will monitor and maintain itself by running several times a week and reporting back any potential problems.

Q. How many watts does it take to run a house?

Larger houses will need more watts to fully power than small ones. A 1,000- to 3,000-square-foot home can usually get by on a 16,000-watt (16 kW) generator, while a larger home between 3,000 and 5,000 square feet would need a 20,000-watt (20 kW) generator.

Q. How long does a whole-house generator usually last?

A good standby generator should last at least 20 years if well maintained. A heavily used generator will last for a shorter amount of time and will need to be maintained more frequently to increase its lifespan.

Sources: HomeAdvisor, Fixr, HomeServe, Angi, HomeGuide

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