How Much Does a Standby Generator Cost to Install?

Standby generators come in a wide variety of sizes, varying in cost from just over $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. 

Understanding 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.

A backup generator can be connected to all of your home’s electrical circuits for Whole House Coverage, or just a few “essential circuits”.  Here are a few examples of common essential circuits homeowners might want covered with a backup generator:

• Garage door or gate openers
• Security system
• Refrigerators and freezers
• Electric ranges
• Kitchen receptacles
• Washing machine and clothes dryer
• Essential light circuits
• Receptacle circuits for medical equipment, TV, and WIFI
• Fan blower motor for gas furnaces
• Water well pumps
• Sump pumps
• Air conditioner

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 backup generator system, especially high energy circuits like ovens, clothes dryers, and air conditioners.

The table below provides estimated wattage of various electrical appliances in most homes:

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-$6,000. The popular Cummins RS20A Kit includes a 200-Amp Automatic Transfer Switch (ATS) for under $6,000.

What is a Transfer Switch & Determining Which Size You Need

The Automatic Transfer Switch (ATS) monitors utility power and automatically switches to generator power during a power outage. The ATS also prevents electrical currents from traveling in the wrong direction across utility lines during power outages, thus allowing for safe connections.

There are two main types of transfer switches: Manual Non-Automatic Switches and Automatic Transfer Switches. Portable generators are typically connected to a manual switch while standby generators use an automatic switch.

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 main breaker panel with a 100-Amp load center, you will need a 100-Amp Automatic Transfer Switch.

Be sure to check the size of the main breaker on the load center(s) installed at your home. The size of the main breaker will determine the size of the ATS.

If your home has multiple load centers and you wish to have the generator power the whole house, you will need an ATS for each load center. Homeowners looking to cover Just the Essentials, instruct the installer to move essential circuits to one of the load centers and relocate the non-essential circuits to other load centers not covered by the generator. Purchase an ATS for only the load center(s) covered by the generator.

About Service Entrance Rated and Non-Service Rated Switches

Service Entrance Rated Switches are required for Main Breaker Panels or load centers. The Main Breaker (typically 200-amps) controls the flow of power throughout the panel.

A Sub-Panel does not have a main breaker. Instead, the circuit breaker controlling the flow of electricity to a Sub-Panel is found on a Main Breaker Panel and typically the circuit breaker is 50-100 amps. If you only wish to power circuits on an installed Sub-Panel, you will need a Non-Service Rated ATS.

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 Main Breaker Panels, gas heat and gas 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.
  
  NOTE: Do keep in mind that Cummins air-cooled generators have built-in load management capabilities enabling the operation of one air conditioner at a time. When one A/C cycles "off", generator power will become available to operate the other A/C. One of the two A/Cs can be set as a priority load.

The “essential circuits” listed above might be installed on both Main Breaker Panels.  Your instructions to the installer will be to move all "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 Main 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 Automatic Transfer Switch appropriately sized to match the size of the connected panel.

If your 2-story home has two Main Breaker Panels rated at 200-Amps and the Essential Circuits are located on one of the panels, your installation will require just one 200-Amp ATS that is also service-entrance rated. Or, if the essential circuits are installed on a Sub-Panel, your installation will need an appropriately sized automatic transfer switch that is non-service rated.

Now, let's suppose your home has just one 200-Amp Main Breaker Panel. Your installation will require a 200-Amp Service Entrance Rated ATS. If you are also installing a Cummins RS20A 20kW generator, the generator can be programmed to load-shed non-essential loads like electric ovens, clothes dryers, and electric hot water heaters. The same generator can also manage the loads of two air conditioners.

If your air-cooled home standby generator will be load shedding an oven, clothes dryer, or electric hot water heater, be sure to order the Cummins 50A Load Management Module for each load to be shed. Air conditioning circuits do not require a load shed module because a low-voltage connected can be made to the thermostat.

Let’s Talk About Overall Project Costs

Costs for typical 20kW generators (with ATS) vary from just under $6,000 for a  Cummins Generator. .

The Cummins RS20A Home Standby Generator is growing in popularity with homeowners for good reason.  It also happens to be the quietest air-cooled generator on the market.

Installation costs can vary widely.  The lowest cost installation can be obtained when the generator is positioned at or near the home's gas meter and the electric meter is also located on the same side of the house as the gas meter. Installation costs will range higher when the generator is located away from the gas meter and when the two meters are on opposite sides of the home..

When budgeting for a professionally installed backup 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, $6,000.00 for the generator equipment, expect the total project to be around $12,000.00. If the generator is positioned away from gas and electric meters, installation costs will be higher. Project costs for liquid-cooled generators begin in the mid-teens and can often range well in excess of $20,000.00.

The Cummins RS20A air-cooled generator is the generator of choice in many installations. Use it as a Whole House solution for modest sized homes under 2,000 square feet (with gas heat and hot water). Or use the same generator as a Managed Whole House solution for homes up to 3,000 square feet. Larger homes should use the RS20A to cover Just the Essentials with all essential circuits relocated to one of your Main Breaker Panels.. 

If your home exceeds 3,000 square or is an all-electric home and you’re looking for a whole house generator, you will likely need to focus on liquid-cooled generators.

The best advice we can offer anyone considering a backup generator is to consult an industry professional. We’ve witnessed 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.

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 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 to calculate the anticipated electrical loads, better still, consult an industry professional. Work with an experienced generator installer and, preferably, also an authorized dealer for the manufacturer.

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

If you're in the market for a standby generator, we encourage you to call us with questions or assistance in generator sizing. Call us today at 901-379-8097.