By Meghan Wentland | Updated Aug 5, 2022 4:33 PM

When lightning strikes too close to home and the power flickers then goes out, what is your first thought? The freezer full of meat? Children who will panic if they wake up without a night-light? Critical medical equipment? The HVAC system? Power outages are inconvenient no matter how brief they may be, but they can be expensive or even dangerous in some circumstances, especially if the outage is prolonged. A whole house generator protects your family and home by automatically sensing the power loss and triggering a backup power system. The typical cost range for a whole-house generator is $5,000 to $25,000, with homeowners paying $9,520 on average.

Many people envision a Home Depot generator 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 you’ll see on sale during storm season. 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. They can be especially popular in areas regularly threatened with heavy snowfall or high winds or in remote areas where the power lines are less reliable. While the average whole house generator cost nationwide is $9,520, several options can raise or lower this cost based on your home’s needs. It’s essential to understand the possibilities and know the terminology before you start shopping so you can develop a realistic budget and decide if a whole house generator is right for you.

Whether you have a small portable gas generator or a massive standby unit, the cautions you’ll need to take when using them are the same. Never, under any circumstances, operate a generator inside your home or garage—even with the doors and windows open. Carbon monoxide is a lethal gas that can accumulate quickly, and by the time you know 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 care must be taken for proper ventilation and air exchange so you can keep your home warm and bright but also protect the people living in it.

The demand for whole house generators varies based on weather conditions, market, and region. You’ll 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 you’ll find when you begin shopping, and these choices can affect your total cost by thousands of dollars. You’ll want to know the size of your house and electrical panel so you don’t buy more power than you need. Other options may be nonnegotiable.

There are two kinds of generators for a house: fixed and portable. Most generators capable of powering an entire home are fixed: permanently installed on the outside of your home and hardwired into your electrical system. They come in sizes ranging in power from 7 to 38 kilowatts and cost from $800 to $20,000. To power a 2,500-square-foot home, you’ll want a standby generator with about 25 kilowatts of power. Another option is the portable generator, which can range in power from about 2 to 8 kilowatts. 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 $200 and $6,000.

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. You’ll see generators 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.

Every generator, whether portable or fixed, 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. Fixed standby generators, wired into your home’s electrical panel, will sense the power interruption to the house and automatically turn on, ensuring minimal loss of power and potential damage to the home and its systems. These generators also include a manual start switch as a backup.

Installed generators 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. 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.

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

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

An installed generator hooks into your home’s electrical system, so you’ll need a permit 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.

Along with installation, the cost of the generator itself is high, but it can save money in the long run by allowing you to remain in your home during a lengthy power cut. After the purchase and installation, however, there are still some costs to account for.

Standby generators automatically run themselves 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 let you know 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. You’ll need to schedule occasional maintenance service by a technician periodically, usually just before the season when you’re most likely to need backup power. Expect to pay between $80 and $300 for this yearly service.

The generator itself can’t help you if you don’t have the appropriate fuel on hand. For an installed generator, this usually means connecting the generator to a natural gas line or sizable liquid propane tank. If you’re using a tank, you’ll need to keep the tank filled, and the costs for this will depend on your contract with the gas provider. Portable units need to be filled as they are used because both gasoline and diesel fuel have short shelf lives and will lose effectiveness if left sitting in a tank (and could potentially damage the tank and sensors as well). Price out how much gas you’ll keep on hand and change it out periodically to gauge your cost of use.

Several potential upgrades will make a generator more efficient. A wireless monitor provides access to the status of the generator. If you’re away from home and there’s a power outage, you can make sure that the generator has kicked on. These monitors cost between $200 and $400. A smart load manager can help you create different zones in your 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.

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 you need it.

Generators powered by natural gas are more expensive at the time of purchase than gasoline generators, averaging between $2,000 and $21,000. There’s little fuel waste because the generator uses fuel drawn directly from the utility when it needs it. While the natural gas prices are often a bit lower than gasoline, a natural gas generator uses more gas to power your home than other types.

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 as they get larger.

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

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 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, costing between $500 and $3,000.

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 your 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.

Portable generators are less expensive and take up less space on your property than whole house generators—and they can be loaned to friends and family if they need a power boost. And really, how often do you need to power your whole house 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 house generator.

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

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

Have fast, torrential rains? Live in a floodplain or just have poor drainage around your home? If so, you probably also have a sump pump. Sump pumps are an automated way to keep your basement 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 your basement has also knocked out your power, your sump pump can’t help, and you’re likely to lose the contents of your basement and potentially have structural damage to your home. Your sump should be supported by a standby generator that will make sure the sump pump can do its job.

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

Generators are labeled by size using the total number of kilowatts they can produce. There’s no sense in purchasing a generator with more power than you need, and choosing one that is significantly underpowered for your needs will be frustrating and feel like a waste of money. The best way to determine the correctly sized generator for a house is to invite an installer to come to your home and assess your property. They can take stock of what you would like the generator to cover and recommend size and type. It’s a good idea to collect several of these estimates. Suppose you’d prefer to estimate yourself, whether to check the accuracy of a contractor’s bid or to choose the size on your own. In that case, you can look at each item you’ll need to be plugged in while using the generator, including appliances, electronics, the water heater, HVAC systems, and the garage door. Each should be marked with a label that shows how many watts the item uses.

Your formula will look like this:

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

The number of kilowatts is your guide: If it’s between two sizes of generators, you can choose to size up for comfort or size down if you’re willing to engage in strategic power use during an outage to save a few dollars.

If a portable generator adequately covers your needs, 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. The units are large and heavy and have to be wired into the existing electrical system and possibly fuel lines. Pouring the pad incorrectly, installing the connections improperly, or even pulling the wrong permits can be dangerous and costly errors, so it’s best to hire a professional to make sure the installation is completed smoothly.

Saving money on a generator purchase is primarily a matter of patience and timing and knowing exactly what you need.

You’ll want to ask a potential contractor some questions before you hire them. As always, you’ll need to ask about licensing and insurance (and the licensing and insurance of any subcontractors or workers who are expected to take part in your project). You’ll also want to ask for and check references. Additionally, here are some other questions specific to generator installations you’ll want to have answers for.

Before choosing and having a whole house generator installed, you’ll need to make quite a few decisions. Those decisions about size, type, fuel, and other elements will determine the price you’ll pay for heat and light. These can start to feel like too many choices, so just ahead are a few of the questions we’re most often asked about this topic, along with answers to help you get started.

This depends on the size of your home, the size of the generator, and how much you’re trying to power. On average, a small portable generator costs about $30 to $70 per day to run, while a 15- to 20-kilowatt generator that powers the entire home will cost about $50 to $150 per day. You’ll need to factor in fuel costs, which are dependent on the type of fuel, which could be as much as $30 per day in gasoline alone.

Generators only operate outdoors, so it’s not surprising that they’ll need a little maintenance periodically. At the cost of between $75 and $300, annual maintenance should keep your generator in excellent condition. A standby generator will monitor and maintain itself by running several times a week and reporting back any potential problems.

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.

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 should be maintained more frequently to increase its lifespan.

Sources: HomeAdvisor, Fixr, HomeServe, Angi, HomeGuide

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