Best 20KW Standby Generator

We all know the importance of electricity in homes, so we won’t dwell much on that. To ensure that you don’t lack power in your house during an outage, it is necessary to install a standby generator.

To make it easier for you to be able to choose a reliable standby generator, we have reviewed some awesome standby generators below. They all generate at least 20KW, so they are for homes that need that amount of electricity.

Before we go forward, it is important that we advise you not to go for this category of generators if you don’t need up to 20KW. You don’t need to pay for what you won’t use.

Since this article is meant for the best 20KW generators in the market, we combed the market for them. After testing many of them, we came up with the six below as the best. When you see their features, you’ll agree with us that they are the best.

In selecting these generators, we considered low fuel consumption, low noise, high output, high Amazon ratings, and durability. We can assure you that all the generators below have all the features. So, sit back and read the reviews through.

Our Picks of 6 Best 20KW Standby Generators:

1. Generac 7043 Home Standby Generator 22kW/19.5kW

What we love most about this generator is its app. When you install it on your smartphone, you can monitor the generator through the app irrespective of where you are.

Even if you’re in Africa and the generator is back home, in the United States, you’ll still be able to monitor it through the app.

We also love its 5-year warranty because no so many generators offer that.  The gen-set has a dimension of 48 by 25 by 29 inches and a weight of 515 pounds.

We are also happy to inform you that this generator is built in the United States. It is capable of generating 22KW. Its LCD display unit gives important information like the maintenance intervals and the battery status.

Its strong enclosure makes it strong enough to weather all storms. Its noise level and fuel consumption are both low. In addition, it is durable. Its Amazon rating of 4.6 stars sums everything up.


  • The LCD unit of this gen-set gives important information.
  • It weighs 515 pounds.
  • The generator has an app through which you can monitor it remotely.
  • With an output of 22KW, you’ll be able to power all your appliances.
  • An Amazon rating confirms the performance of the generator.
  • It has a low noise level.
  • Its aluminum body can withstand tough weather conditions.
  • The product is built in the United States.
  • It has a dimension of 48 by 25 by 29 inches.
  • If you buy it, you’ll enjoy its 5-year warranty.

2. GENERAC 20 kW, 60 Hz, Liquid-Cooled Automatic Standby Generator

This generator generates exactly 20KW. Its system is liquid-cooled. The generator is made of aluminum, so it is resistant to rust and corrosion, and it will withstand tough weather conditions.

It runs on diesel. We also noticed that its fuel consumption is low, just like its noise level.

We can assure you of its durability. Although it does not have any rating on Amazon, it is highly rated on other platforms.


  • The generator is a heavy-duty machine.
  • It runs on diesel.
  • The body of the generator is resistant to corrosion.
  • It is also resistant to rust.
  • The gen-set can withstand all weather conditions.
  • Its fuel consumption is low.
  • It does not make as much noise like many other generators in its category.
  • We can tell you that it is durable.

3. Generac 5734 GP15000E 15000 Running Watts/22500 Starting Watts

We got attracted to this generator because of the amount of electricity it generates. Only very few standby generators can generate up to 22.5KW. Another distinctive feature of this generator is its orange color.

It will always stand out among numerous generators. It has a weight of 373 pounds, which is great for a generator that gives 22.5KW.

It has a dimension of 38.5 by 30.75 by 48.5 inches. The voltage of the generator is 120 volts. It comes with a tank of 16 gallons. You start it with a recoil start or its electric start. From our experience, we can tell you that both options are convenient. We tried its recoil start and the generator came on in the very first attempt.

While it is a good idea to check its oil level always, it is not necessary. Do you know why? This masterpiece comes with a low-oil sensor that will shut it down when the oil level is low. This is a safety feature meant to protect the engine of your generator. We also noticed that its noise level is fairly low.

This generator can run for ten hours at 50% load, and it can run much longer with a 25% load on it. Of course, we agree that moving 300-pounder can be a handful. That’s why we appreciate its two wheels that make mobility much easier.

Hence, you can change its position as often as you like. Since it is movable, you can push it outside to use it and push it back inside after using it. Many of its users have confirmed its durability. That’s probably why it has an Amazon rating of 4.3 stars.


  • This workhorse runs for ten hours at 50% load capacity and runs longer with less load.
  • Its voltage is 120V.
  • Having a high Amazon rating speaks volumes about the product.
  • Its tank can take up to 16 gallons of fuel.
  • The output of this generator is 22.5KW.
  • It weighs 373 pounds.
  • One thing that makes it stand out among others is its orange color.
  • It is rugged and durable.
  • It will shut down automatically when its oil level is low.
  • The dimension of the generator is 48.5 by 30.75 by 38.5 inches.

4. Generac 6729 Guardian Series, 20kW

The finish of this generator is smooth, clean, and sleek. You can’t catch a glimpse of it and not take a second look. We expected much from it in terms of performance and we were not disappointed.

When you buy it, you’ll have the option of running it with natural gas or propane. The device does not have a manual start. It is designed to kick in automatically when a power outage occurs.

To assure you of its safety, it has been certified by EPA, CUL, and UL. Another awesome feature of the product is its 5-year limited warranty. You’ll get up to 20KW from this masterpiece.

Although it weighs a staggering 516 pounds, this shouldn’t be a problem because it is designed for permanent installation. It is needless to remind you that it is rugged and durable.

You don’t need to worry about noise because its noise level is low. It has a dimension of 25 by 29 by 48 inches and an Amazon rating of 3.6 stars.


  • This generator is approved by EPA, CUL, and UL.
  • It has a 5-year limited warranty.
  • The appliance weighs 516 pounds.
  • It has a dimension of 25 by 29 by 48 inches.
  • The generator has the capacity to put out up to 20KW of power.
  • It starts off automatically in the event of a power outage.
  • It is fueled by both natural gas and propane.
  • The fuel consumption of the gen-set is relatively low.
  • And so is its noise level.
  • Its amazon rating of 3.6 stars is fair.

5. Briggs & Stratton 40336 20kW Standby Generator

The most astonishing feature of this generator is its quietness. You may not hear its sound a few meters away.

Yes, it is as quiet as that. With a 20KW power output, you should be able to power a 5-ton air conditioner with it.

The generator will shut down when its engine oil level runs low. It is coated with aluminum to prevent it from corrosion, rust, and harsh weather conditions.

The product also comes with a 200A rated transfer switch. It runs for 20 minutes every week to carry out a self-diagnostic test. This prevents it from disappointing you when you need it most.

Also, it prevents the battery from going flat due to idleness. Unfortunately, the battery does not come with the pack. You have to purchase one yourself.

As a rule of thumb, it is better to get heavy-duty generators like this installed by experts. It is not something you should do yourself. A few of its users have testified to its durability.

It comes with a 5-year limited warranty. Weighing 580 pounds makes it one of the heaviest standby generators in the market. Its dimension of 58 by 36.5 by 72.5 inches confirms that. The product has an Amazon rating of 3.4 stars.


  • The generator outputs 20KW.
  • It comes with a 200A transfer switch.
  • A 20-minute self-diagnostic test every week ensures that it is in top condition always.
  • You’ll enjoy its 5-year limited warranty.
  • The heavy-duty generator weighs 580 pounds.
  • It has an Amazon rating of 3.4 stars.
  • The gen-set has a relatively low noise level.
  • It has a dimension of 58 by 36.5 by 72.5 inches.
  • Some of its users confirmed its toughness and durability.
  • The shipping of the product is fast.
  • It is coated with aluminum to prevent it from corrosion, rust, and harsh weather conditions.

6. Kohler 20RES – 20kW Home Standby Generator

This huge generator generates 20KW, which is enough to power a well-equipped ranch. Although it comes with a 2-year warranty, you need to find out what the warranty covers and what it does not cover.

Based on the experience of a couple of users, the warranty only covers the parts; it does not cover labor. You’ll have to pay the tech guy that comes to fix it.

In addition to what we have said, you still need to check the warranty details because warranty terms change often. This is another generator that does a weekly self-check.

The product is durable and it is backed up with awesome after-sale support. We found that its noise level is fair. It is not unbearable.

Also, it is rugged enough to withstand all weather conditions. It weighs 525 pounds and must be installed on a concrete floor. Also, its amazon rating is fairly high.


  • The generator is capable of generating up to 20KW of power.
  • It runs a weekly self-diagnostic test automatically.
  • The heavy-duty generator weighs 525 pounds.
  • It comes with a 2-year limited warranty (on parts, not labor).
  • You’ll love the brand’s after-sale support. It is awesome.
  • It’s designed to withstand all weather conditions.
  • The noise level of the device is relatively low.
  • You can be sure of its durability.

How Big of a House Will a 20kw Generator Power?

As a matter of fact, it’s not really about the size of a house, but the total power consumption in that house. If you use the size of a house to determine the size of the generator to buy, your decision may not be accurate. This is because we have seen several smaller houses consume more power than some bigger houses.

This is why we will advise you to list out all the appliances in your house and total their collective power consumption. That way, you’ll get a more accurate figure as to how much power you need in your house. That being said, we can give you an estimate. A 20KW generator should be able to power a 2,500 square foot house to a 3,500 square foot house.

 How Much Does It Cost to Run a 20kW Natural Gas Generator?

We will split the costs into three – purchase costs, installation costs, and running costs.

1. Purchase cost

The cost of a 20KW generator ranges from $5,800 – $6,500, depending on its brand.

2. Installation costs

  • Preparation of the site and casting of the concrete pad – $75 to $100 per square foot.
  • The connection of the utility lines – $100 to $150 per square foot.
  • Wiring and the installation of transfer switch – $100 to $150 per hour.
  • Application of the necessary permits for electrical works and plumbing – $250 to $500 each.
  • Required materials – $1,000 to $3,000.

3. Running costs

The running cost of a generator depends on the following three factors – the size of a generator, the price of natural gas, and the generator running load.

Size of generator – Bigger generators consume more fuel than smaller ones. A 20KW generator will consume more fuel than a 5KW generator to power the same appliances.

Price of natural gas – The cost of natural gas is directly correlated to your running cost. If the cost of natural gas increases by 2%, your running cost will increase by the same percentage.

Running load – The higher the load on your generator, the faster it will consume your fuel. So, it will cost you more to run a 20KW on 70% load than running it on 50% load. You’ll buy more fuel and you service it more often.

Generally, running a generator will cost about $0.02 to $2.41 per hour, depending on the factors mentioned above.

How Many Amps Can a 20 KW Generator Handle?

To answer the question, we’ll use this equation: Amp = Watts/ Volts

Big generators have two standard voltages – 120 volts and 240 volts.

With 120 volts

Amp = 20,000 Watts/ 120 Volts

Amp = 167 Amps

With 240 volts

Amp = 20,000 Watts/ 240 Volts

Amp = 83.3 Amps

How Long Can Generac 20kW Run?

According to the manufacturer, the generator can run for more than 500 straight hours. However, we think the figure is not realistic. If you use liquid propane, the tank of the generator is not big enough to accommodate enough fuel for 500 hours. And once it runs out of fuel, the generator will automatically shut down. It won’t start until you top up the fuel.

Furthermore, if the generator runs on natural gas, you don’t need a fuel tank but remember that the gas supply will be shut down when a natural disaster occurs. This is a safety measure. It is meant to prevent fire hazards. So, you won’t be able to run your generator on natural gas if a disaster occurs.

Finally, even generator manufacturers don’t advise you to run your generator for 48 straight hours without rest. They say it will shorten the lifespan of the generator and it will also make repairs and maintenance checks more frequent. Remember, you need to service your generator and change the oil after every 100 hours.

Finally, even though, theoretically, a Generac 20KW generator can run for more than 500 hours, it is not realistic and practicable.

How to Install a 20KW Standby Generator?

Step 1 – Decide on the spot to place your generator. Remember, it has to be at least 5 feet away from your doors and windows. You’ll also have to leave a space of 3 feet in front of the generator for servicing room. And the exhaust of the generator should be directed away from your house.

Step 2 – Create a concrete pad where you’ll install the generator. Wait for the casting to dry fully before placing the generator on it.

Step 3 – Install the generator on the pad and position it appropriately.

Step 4 – Fasten it to the ground with at least four stainless steel bolts.

Step 5 – Get a plumber to run a gas line from your main supply to the generator.

Step 6 – Get an electrician to wire your electrical panel for the generator and also get the transfer switch and the power inlet box installed.

As we always advise people, let professionals handle the installation. If you’re not an expert, don’t handle the electrical part of the installation.

What Will A 20KW Generator Run?

This amount of power is enough for a whole home or ranch. It is enough to power TV-sets, microwave ovens, air conditioners, water pumps, heaters, and all the power-consuming appliances in your home.

That’s why 20KW is a standard. It is generally believed that a standby generator that generates 20KW is enough to power all homes.

How Much Fuel Does A 20KW Generator Use?

The fuel consumption of any generator does not depend much on its power capacity. Rather, it depends on its designed rate of fuel consumption and the load on it.

For any generator, more load will lead to more fuel consumption. Depending on the amount of load on a 20KW generator, it will consume between 1 – 3 gallons of fuel in two hours.

20KW Generator Installation Cost:

The installation cost of a 20KW generator varies widely. It depends on the quality, size, and design of the generator. The bigger the generator, the higher the installation cost. Adding a concrete floor will boost the cost.

It is also necessary to bear in mind that there are different installation experts and their charges for the same job will always differ.

A good way to beat down the installation cost is to pay the supplier for installation. Since you bought the generator from them, you’re likely to earn a huge discount on the installation. That being said, the installation of a 20KW generator can cost between $1,500 to $9,500.

20KW Generator Price:

The prices of 20KW generators also differ widely. The factors that are responsible for the variances are the size, special features, and brand name. Some brand names like Generac, Briggs & Stratton, and Champion are trusted brands.

So, their products will cost more than the products of other brands within the same category. Generally, the prices of 20KW standby generators start from $3,000 and it goes up from there. You can’t really put a cap on it.

Buying Guide – How To Choose A 20KW Standby Generator?

How To Choose A 20KW Standby Generator

Buying a generator is different from buying other products, so you’ll need to apply the tips below.

1. Pick from This list

Some generators do not give problems within the 30-day return window. The problem will occur after the window has closed and you may not be able to return it. Also, generators hardly come with full warranties.

They usually come with limited warranties. That means your generator may be fixed but it will never be replaced. That’s why it is better to pick from the list of tested and trust generators reviewed above.

2. Read User Reviews

It might be a good idea to read user reviews of your preferred generator before you order it. You’ll be able to find out if it has issues that you may not be able to cope with.

Also, you could learn about the common mistakes that users make and how to avoid them. Many brands are deceptive with their warranty.

They’ll promote their product with a 2-year warranty, but users still have to pay for the product to be fixed. When you read through reviews, you’ll find out from the reviews if the company is honest with its warranty.

3. Order it from Amazon

Amazon offers competitive prices on its platform, so you’re likely to get the best deals from Amazon. Also, every appliance you purchase from Amazon automatically comes with a 30-day return window. If you find something you don’t like about your generator, you can return it within 30 days.

Finally, most 20KW generators are heavy. They weigh more than 300 pounds. It takes heavy machinery like a forklift to deliver it. Amazon has partnered with logistic companies that have the required facilities.

4. Find out If it is Permitted in Your Community

Many generators are very noisy, so heavy-duty generators are banned in some areas, while in some other localities, your generator must meet certain requirements.

You must find out about this before you order a generator. You don’t want to order a generator that will pit your neighbors against you.

Final Word

To wrap up this piece, we recommend all the standby generators above. We have tested them all, and we now have confidence in them.