How much does a standby generator cost to install?

Standby generators come in a wide variety of sizes, varying in cost from just under $2,000.00 to $20,000.00 and more.  Installation costs can also vary widely.  It is best to consult a qualified installer to determine what size generator you need for reliable backup power for your home or business. 

Understand Kilowatts and Determining the Size Generator You Need?

Generators are sized in kW or kilowatts, so a 10kW generator will produce 10 kilowatts or 10,000 watts of power.  A qualified generator installer can help you determine the proper generator size after calculating the anticipated electrical loads needed for desired backup power. See this Quick kW Guide of Common Household Appliances to gauge how much power you may need.

Keep in mind, a standby generator can be connected to all of your home’s electrical circuits or just a few “essential circuits”.  Examples of common essential circuits include the refrigerator/freezer, kitchen receptacles, a few light and receptacle circuits, the fan blower motor for gas heating equipment, the security system, garage door opener and, if you have them, water pumps and sump pumps.  Most of these circuits do not require a large amount of power to keep them operational, but it’s important to consider the sum total of each of these loads when sizing a standby system.

A very popular and “easy on the budget” generator is a “20kW” (20,000 Watts) model because they are air-cooled (as compared to “liquid-cooled”) and cost around $5,000.00, that's including the 200-Amp Automatic Transfer Switch (ATS). 

What is a Transfer Switch & Determining Which Size You Need

Transfer switches control the amount of electricity (the "electrical load") that is delivered to each source requiring electricity and prevent the currents from traveling in the wrong direction. So they allow for safe connections, which is why Transfer Switches are mandatory for most electric codes. They also switch power between the grid service and generator, (and between different generators or different grid services). There are 3 main types; Manual, Non-Automatic, and Automatic Transfer Switches. 

The size of the ATS must match the size of the "load center" it will be connected to.  In the 20kW generator example, these are connected to a 200-Amp load center and, thus, come with a 200-Amp ATS.  If the generator you select will be connected to a breaker panel with a 100-Amp load center, then you will need a 100-Amp Automatic Transfer Switch.

If your home is 2,500 square feet or less, a generator with 20kW-25kW should suit your backup power needs well, particularly if you have gas heat and hot water.  If the range top is also gas, all the better.  20kW-25kW is enough to run most house appliances (receptacles), lights, and up to a 5-ton central air conditioner. 

When a generator is connected to all house circuits, the installation is referred to as a “whole house generator installation.”  Connecting only a few essential circuits, or “partial house generator”, can be an effective means of providing power to the essential electrical circuits most important to you, while saving on overall project costs.

Let’s say you are looking for a budget-friendly installation of a “partial house generator.”  You have one or two breaker panels, gas heat and hot water, and you’ve identified the following electrical circuits as “essential” while operating under generator power: 

  • kitchen receptacles and lights (including refrigerator/freezer)
  • the fan blower motor for your gas heat
  • the security system
  • garage door opener
  • downstairs lights and receptacles, and
  • the downstairs central air conditioning unit.  You have a second air conditioner and heating system for the upstairs, but this area of the home is not important to you while operating on generator power.

The “essential circuits” listed above might be installed on both of your breaker panels.  Your objective will be to move the "essential circuits" to one of your two breaker panels.  The panel holding these "essential circuits" can be referred to as your "generator panel" because the generator will energize only the circuits located on that circuit breaker panel.  The other circuit breaker panel will hold non-essential loads like the upstairs circuits, the upstairs air conditioning and, perhaps, your laundry equipment.  Those circuits will not be energized by the generator.

So--in the above illustration, you would need just one (1) ATS appropriately sized to match the size of the circuit breaker panel it is connected.

If your 2-story home has just one circuit breaker panel rated at 200-Amps, there is no need to install a second panel for this installation.  You just need a 200-Amp ATS that is also service-entrance rated.

Most manufacturers include ways to load-shed the non-essential loads, such as a second air conditioner or hot-water heater.  Even though the upstairs lights and receptacles are still “hot”, these circuits will not consume power from the generator unless a light is turned “on” or an appliance is operated from a receptacle.  What’s important is to disable heavier non-essential loads such as air conditioning, electric hot water heaters with load-shed devices available from the generator manufacturer.

Determine the Right Generator for Your Power Needs?

Now that we’ve identified which electrical circuits are important, we can project the total electrical load from these same loads.  Here’s a sample scenario during the summer months where we are doing the laundry but we’re conserving power and not operating the washing machine and dryer at the same time.  We’re also not operating any cooking appliances.  Someone is watching TV and downstairs, one ceiling fan is “on” as well as the downstairs air conditioner.  Let’s look at the results:

kW/Electricity Guide We’re conserving power where possible because, for budgetary constraints, we decided to have a 20kW air-cooled generator installed.  The 20kW generator coupled with a 200-Amp Automatic Transfer Switch can be connected to all house circuits installed on a 200-Amp Load Center, making it a “whole house generator” for homes 2500 square feet and less.  Keep in mind the generator is rated at 20kW when using LP as the fuel source, and 18kW for natural gas.

Let’s Talk About Overall Project Costs

Costs for typical 20kW generators (with ATS) vary from around $5,000 for a  Cummins Generator.  Most manufacturers now offer a 5-year limited warranty (generally, 5-years on parts and 2-years on labor) with an optional 5-year comprehensive warranty.

The Cummins RS20A Home Standby Generator is growing in popularity with homeowners for good reason.  It happens to be the quietest air-cooled generator on the market and Cummins has been awarded "Brand Leader" recognition for each of the past five years at Builder magazine.

If you live in the northern half of the USA, you will need a cold-weather kit.  We have the generator and transfer switch priced at less than $4,900.00 and you can check it out here.  If you live in the south, no cold weather kit is required, so the generator and switch can be purchased for less than $4,600.00.  View it online here.

Installation costs can vary widely.  The lowest cost installation can be obtained if the electric meter and gas meter are located next to each other on the same side of the house.  Installation costs may range a bit higher when the generator is located away from either the electric or gas meters, especially in situations where the electric meter is on one side of the house while the gas meter is on the opposite side of the house.

When budgeting for a professionally installed standby generator for your home, it is best to assume installation costs will closely approximate the cost of the generator equipment.  This isn’t always true but, more often than not, the rule of thumb is fairly accurate.  So—if you spend, say, $5,000.00 for the generator equipment, expect the total project to be around $10,000.00.  Project costs for liquid-cooled generators begin in the mid-teens and can often range well in excess of $20,000.00.

The 20kW air-cooled generator is the generator of choice in 70% of all installations.  Use it as a whole house generator for homes under 2,500 square feet (with gas heat and hot water), or as a partial house, essential circuits only generator for larger homes.  If your home exceeds 2,500 square or is an all-electric home and you’re looking for a whole house generator, you will need to focus on liquid-cooled generators.

The best advice we can offer anyone considering a standby generator is to consult an industry professional.  We’ve seen folks make the mistake of putting the cart before the horse by purchasing a generator without any thought of what they want to power with the generator.  I’ll never forget the gentleman who found a “great sale” on a standby generator for $1,900 at a big box store.  He bought the 7kW (that’s only 7,000 watts) generator, then called us for a quote to install it.  I asked him, “which circuits do you want to power with your new generator?”  He responded, “the entire house.”  The man lives in a 4,000 square foot home with three air conditioners.  Needless to say, I had to explain why the installation scenario he described would not work.

Avoid making this mistake ...

You might be shopping at a Big Box Store and find a standby generator with lettering on the box claiming to be a “Whole House Generator”.  More than likely, the kit includes a 200-Amp ATS that connects to your home's 200-Amp service, thus, covering the entire house.  The generator itself can be as small as 12kW or up to 22kW.  

This is important:  The term “Whole House” refers to the ATS, not the generator.  If you connect a 200-Amp ATS  to your home's 200-Amp service, you now have "Whole House Coverage". 

If you are looking for a Whole House Generator, it is critically important that you calculate the anticipated electrical loads, better still, consult an industry professional.

An “industry professional” is not necessarily any electrical contractor.  While there are many gifted electricians out there who can quickly resolve just about any electrical problem, the truth of the matter is many electricians have little or no experience installing a standby generator.  The lesson to be learned here is to work with an experienced generator installer and, preferably, also an authorized dealer for the manufacturer.

If you are shopping for a talented generator installer, ask each this question:  “How many standby generators have you installed in the past 12 months?”  If any of them respond, “Oh, I think I can probably figure it out,” you would be well advised to take a pass on any quote they offer, even if it is your low quote.

Buckeye Power Systems is a Certified Cummins Dealer, offering customers a full line of quiet, high-performance generators for reliable residential or business standby power. 

If you're in the market for a standby generator, we encourage you to call us for even better pricing than found on our website.  Manufacturers require dealers to advertise at a set Minimum Advertised Price, but we can sell the equipment to you for less when you call us at 901-379-8097.