There are few options for a portable generator that has the watts to supply an entire house with electricity during an outage. Our Generac GP17500E review examines the best portable generator for high-power output applications. As one of the most recognized generator brands, Generac is often the first choice for both homeowners and contractors.

If you’re looking for a portable generator capable of keeping your entire home powered up during an outage, your choices are somewhat limited. Standby generators involve a costly installation and cannot be moved. This makes the Generac GP17500E totally unique. It’s the most powerful portable generator on the market. Generac is a market leader in the field of standby and portable generators. After the generator review, I’ll provide some background information on the brand.

Over the years, I’ve reviewed countless portable generators, many of them powerful enough to provide adequate home backup power or a full jobsite. Of these, the CAT RP12000E stands out as one of the most remarkable. The Westinghouse WPro12000 is another great choice, and quite reasonably priced too. However, neither of these generators can match the 17,500 running watts and 26,250W peak power that the Generac GP17500E provides. This fact has made the incredibly powerful Generac 17,500W portable generator one of the most popular on the market.

For the power it provides, the Generac GP17500E is wonderfully affordable. It is also an incredibly robust machine. Offering even more reasons why this is such a sought after portable generator. Though a generator of this size is in no way cheap. Regardless of the brand, you should expect to pay over $2,000 for any generator with this kind of output.

Many generator buyers aren’t willing to pay this much for a generator that may only be used once or twice a year. For those looking for a more affordable, albeit less powerful generator, I’ll also be reviewing the Generac GP5500 portable generator, with 5,500 running watts and 6,875 peak watts. Same brand, same great quality, just much cheaper.

Generac GP17500E (5735) ǀ The Full Review

Generac GP17500 17500W portable generator

Features:

  • 120V/240V; 17,500 running watts; 26,250 peak watts
  • 992cc Generac OHVI engine
  • 16-gallon gas tank; 10-hours runtime at 50% rated load
  • Lifting eye
  • Idle control for reduced noise and improved fuel consumption
  • Heavy duty frame and 12.3” wheels
  • GFCI 120V 20A outlets
  • Digital hour meter
  • Electric starter. Group U1 battery included

Link to Amazon

Review:

The Generac GP17500E is exceptional when it comes to high power output. As I pointed out in the introduction, this is the most powerful portable generator around. The rated power of 17,500W can be closely matched by some other portable generators. But the incredible peak output (26,250W) is unrivaled. This allows for massive startup current capabilities. On a jobsite, where you’re likely to be using several high-powered tools, this is a significant advantage.

If you’re using electric grinders, hammer drills, and similar heavy equipment, you can run into trouble when these are staring and stopping regularly. A common occurrence on a busy jobsite. Some tools can have an initial inrush current of up to 4KW. This is a brief power demand, only when the tool starts. When you have several tools starting simultaneously, most portable generators will trip because of a current overload. With over 26KW startup capacity, this should never happen if you’re using the Generac GP17500.

This high-power startup capacity can be just as much of an advantage for the home user. Generally, a portable generator producing upward of 15,000 watts should be sufficient for most of your home appliances and electric equipment. If you have air conditioners, pumps, and refrigerators, you could occasionally experience random generator tripping. When several of these appliances happen to start at exactly the same time, the peak power demand will exceed that of most portable generators. The Generac GP17500E can handle a large central AC (or a number of smaller ones) without working up a sweat. Refrigerators, heat pumps, washing machines, basically any equipment that uses an inductive electric motor, will require the same high startup (peak) wattage. You never know when these appliances will start, as most have automatic cycles. When several high startup appliances start simultaneously, the demand can be huge. This is why I say this is the best portable generator for supplying a home during an outage. It compares to, even beats, many entry-level standby generators. With the advantage of portability.

Okay, at 390-pounds, the word portable can be a bit of a stretch. Though this is inevitable. A robust generator, with a super tough 1¼” hardened steel frame, is going to be a weighty machine. Add to this, a mighty 992cc engine and massive 120V/240V alternator, the pounds just keep adding up. To help you move this chunky beast about, they’ve fitted heavy-duty 12.3” pneumatic wheels with all-terrain tread. A full loop handle, and lifting eye, give you the best possible means of portability, given the size and weight of this generator.

The Generac OHVI 992cc engine needs to be understood to be appreciated. Generac is one for the few generator manufacturers that build their own engines, developing these engines specifically for generators. This makes the engine fitted to the Generac GP17500E perfectly equipped to handle the demanding conditions for a generator with this capacity. One important fact is that Generac OHVI engines are made in the USA. Whereas most of their other portable generator engines are made elsewhere. They clearly view the OHVI engine, used to power the Generac GP17500E, as one of their premium products.

When output demand remains constantly high, overheating, and consequent engine wear, can take its toll. Using pressurized lubrication, like an automobile engine, this powerhouse has improved output, lower engine wear, and less chance of overheating. Basically, an oil pump replaces the conventional splash oil lubrication system, generally used for most smaller portable power equipment engines.

An amazing thing is the large oil cooler. This is something I’d expect to see on a high-performance engine, not common on portable generators. Indicative of the Generac advantage, purpose building their generator engines. Cooling the oil in this way, ensures the engine operates at a lower temperature. The large oil filter promotes longer engine life and improved service intervals, every 2,000 hours. A digital hour meter keeps track of runtime, so you know when it’s time to service the generator. As we’ve come to expect from any generator engine worth its salt, the Generac GP17500E has automatic low oil shutdown to protect the engine. A pressure sensor at the oil pump constantly monitors the oil pressure, cutting power to the ignition system when the pressure drops too low.

Fuel consumption is reasonable for a generator of this size, 5.5 kilowatt-hours per gallon. Certainly not as economical as Honda or Westinghouse generators, the Generac GP17500E is still a little above average in the fuel economy department. Thanks to an enormous 16-gallon gas tank, you have a very convenient runtime: 10-hours at 50% load from a tank of gas. A fuel gauge on the gas tank allows you determine when to fill her up. Most users find that they can go for an entire day, without the need to add more gas. Unfortunately, this is one of the few Generac engines that is not CARB certified, making it legal only in 49-states.

DIY user maintenance and operating procedures are straightforward and easy. The gas filler is really big, eliminating the chance of spillage when refueling. Access to the air filter is at the top of the generator. The gas tank has been molded and the filter housing is neatly tucked into this space, making it really easy to open and clean the air filter. The dipstick, for checking the oil level, is situated next to the large air filter housing. Thumbscrews, mean you don’t need any tools to open the air filter. The oil filler is also positioned for maximum convenience, with a reasonably large filler opening.

Yet another amazingly cool design feature is the oil drainpipe. Instead of lining a pan up under a drain plug, and all the guesswork that goes with it, a pipe is tucked in behind the oil filter. When you need to drain the engine oil, you simply pull this pipe out, it has about a foot of reach. The pipe has a valve on the tip. So you place the pipe over your oil pan and open the valve, no mess, no fuss. I absolutely love this. Holding this massive engine securely, are 4 X heavy-duty rubber engine mountings.

Starting the Generac GP17500E is simple enough. The fuel shut off valve is on the tank; you turn this manually. The choke and switch for the electric starter are both mounted on a plate at the back of generator, not on the front panel. This means you have to move about the generator a bit to start it, but this is not complicated. Once running, the generator is smooth and unrelenting. I must say though, this is definitely not a quiet generator. The only real issue mentioned in customer reviews, has been the noise levels. It has a low idle switch, which helps reduce the noise when the generator isn’t under load. This also helps reduce fuel consumption. As soon as you use any power, the engine starts to roar like an angry bear. A sound insulated generator enclosure will certainly help mitigate this issue.

Generac GP17500E Generator user interface

The Control panel is mounted to an industrial-style metal box at the back of the generator, below the large loop handle. This is a fairly rudimentary panel, without any fancy electronic gadgets. Only a small LCD screen, displaying running hours, gives us the impression that this is a modern generator.

The outlets are perfect for both jobsite and home backup power applications. Because this industrial-grade machine delivers 145.8A continuous power at 120V, or 72.9A at 240V, you need sufficient power outlets to make full use of this power.

The 125V/250V (14-50R) 50A outlet is ideal for connecting the Generator to your home electric panel, through a transfer switch. This outlet is supplied by a main 2-pole 50A breaker. Of course, this is less than half the total output at 120V. Not top mention the 218.75A peak power (at 120V). You always have the option of using the 125V/250V (L-1430R) 30A outlet as well. The generator also has 2 X L5-30R 30A 120V outlets. This would mostly be for high-amp tools and pumps, of particular importance on a jobsite. There are 2 X 5-20R 120V 20A duplex outlets. This means a total of four standard 20A household receptacles, two of which have GFCI protection. All the outlets have their own dedicated circuit breaker. If you want to charge 12V batteries, the generator also has a 10A 12VDC outlet.

Most people are drawn to the Generac GP17500E for the extraordinarily high power output. While this appeals to me greatly, I’m blown away mostly by the technical aspects of this generator. Generac obviously know what it takes to build an industrial grade generator and have paid strict attention to every detail. Anyone who knows engines, will appreciate the oil cooling radiator and pressurized oil pump. Superbly designed for easy maintenance, this machine is immaculately practical. These are all reasons why the GP17500E is a top seller, despite being more expensive than the smaller machines. It’s a big favorite amongst homeowners, contractors, and off-grid applications. Having made a detailed inspection of this machine, I’m sold on the durability and practical design. Domestic users will appreciate the 2-year warranty. For commercial generator owners, the warranty is limited to 1-year.

Generac GP17500E Downloads:

Generac GP17500E Spec Sheet [PDF]

Generac GP17500E Owner’s Manual [PDF]

Generator Watt Calculator [PDF]

Generac GP5500 (5939) Review

Generac GP550 review

Features:

  • Generac’s OHV engine with splash lubrication provides a long engine life
  • Low-oil level shutdown automatically safeguards engine from damage, and an hour meter to track maintenance intervals
  • Large-capacity steel fuel tank with incorporated fuel gauge provides durability and extended run times
  • Covered, circuit breaker protected outlets for added protection
  • Hardened steel-tube cradle for added durability and strength

Models:

Generac GP5500 (5939): EPA Certified (49-states)

Generac GP5500 (5945): CARB Certified (California)

Generac GP5500 (5975): CSA Certified (Canada)

Link to Amazon

Review:

While the Generac GP5500 is much cheaper than the GP17500E, roughly one third the price, it cannot be seen as an equal rival to mammoth 17,500W generator. Apart from an obvious power difference (the GP5500 delivers 5,500 running watts and 6875W peak power), this generator doesn’t share all the heavy-duty industrial grade traits of its more expensive stablemate.

This isn’t really a comparative review between the Generac GP17500E and GP5500. Though I should point out the major technical differences between the engines used to power these generators. The 992cc mega-engine powering the GP17500E is quite unique in its incredibly robust design. In contrast, the 389cc engine, designed for the Generac GP5500, is more conventional. This engine uses regular splash lubrication, like just about all other portable generators. It also doesn’t have an oil cooler. No surprise here, the GP17500E is a notable exception to rule in this aspect.

Emissions are all up to standard. Though, you’ll need to buy the correct model number, depending on your geographical location. California and Canada have different environmental regulations to the rest of North America and Generac has decided to manufacture three different versions of the GP5500, EPA certified (49-states), CARB certified (California), and CSA certified (Canada). All three models are available on Amazon, you can use the links provided above to check on their respective pricing.

I have to say, I find the fuel consumption for this generator sorely disappointing. Even the Generac Gp17,500E is not that good at 5.5 kilowatt-hours per gallon. Well, this smaller generator only manages 3.8 kilowatt-hours per gallon. In terms of generator economy, you want to get the maximum kilowatts per hour from a gallon of gas. As you can see, the Generac GP5500 is not a winner in the race for low fuel consumption. While this rather dismal performance will increase your running costs, it won’t be an inconvenience in terms of runtime. Generac have supplied this generator with an extra-large gas tank in relation to its engine size. With a full tank of gas (7.2 gallons), the GP5500 will run for 10-hours at 50% load. The gas tank has a small fuel gauge, so you’re able to view the level as this thirsty machine guzzles down the gas.

One area where this mid-sized generator displays true Generac design integrity is in the tough frame and wheel kit. Like the more industrial-grade machines, the Generac GP5500 has a hardened steel 1¼” frame and solid 9.5” wheels. A strong fold down handle ensures easy portability. At 170-pounds, this generator is little on the heavy side. Though this weight is quite manageable and is indicative of high quality metal components. Always a good thing, in my opinion. When you consider that the GP5500 doesn’t have an electric starter, this weight vs durable materials becomes quite significant. There’s no starter motor, or battery, to add to the overall weight of the generator. Just about all 170-pounds of this machine is tough, solid metal.

Controls, functions, and outlets, are just what you need and not much more. An on/off switch and choke are fitted to the engine, with a fuel valve at the tank. You have to use some human power, as this generator only has a recoil starter. But it’s an easy-starter and runs well without any hassles. The electric outlets have protective plastic covers, keeping dust and moisture out. I always like to see this on a portable generator which can often find itself in pretty harsh operating conditions.
Generac GP5500 user interface

The electric circuit breakers vary slightly between the different model numbers, inline with regional compliance. The 5975-2 (Canadian model) and 5945-1 (California model) have a single 2-pole 25A main circuit breaker, the 5939 (EPA models) are fitted with 2 X single pole 25A breakers. The 5945-1 California version also has GFCI protection for the 20A duplex outlets, whereas the Canadian and EPA (49-state) models don’t. With the exception of the main 25A breakers, the control panel for all models look like the control panel image (above) and have the same outlets. This means a 120V/240V 30A, L14-30R outlet, and 2 X 120V 20A, 5-20R duplex outlets. All Generac GP5500 variants are equipped with a digital hour meter to keep track of service intervals.

The Generac GP5500 is a very capable general purpose, light to medium duty portable generator. The core market for these generators are home and recreational users. For it’s portability and power output, the Generac GP5500 is an incredibly versatile machine. At home, you can function quite comfortably during an outage, using a refrigerator (or two), room air conditioners, and all the regular smaller appliances. Used as an RV camping generator, the Generac GP550 is tops. Personally, I wouldn’t recommend this as the best portable generator for contractors. It’s a pretty tough workhorse, but I wouldn’t think it will hold up too well for daily heavy-duty applications. With that said, I know some contractors have used this as a jobsite generator and have been quite satisfied with the performance. It has a 1-year commercial warranty, so Generac are fairly confident that the GP5500 is capable of meeting pretty high standards. For residential use, the warranty is 2-years.

Generac GP5500 Downloads

Generac GP5500 Spec Sheet [PDF]

The Generac Brand

Generac Global Head Quarters

The history behind the Generac brand is a heartwarming, all American tale. From truly humble beginnings, Robert Kern, started manufacturing portable generators in his garage in Wales, Wisconsin. With a workforce of only five, he implemented his own unique generator designs. A dedication which has seen Generac grow into the biggest US generator manufacturer in the decades that followed. Today, Generac holds an estimated 75% of the generator market. These include industrial, commercial, and residential standby generators, as well as portable generators.

In the early years, Generac broke into the competitive portable and vehicle-mounted generator market, by partnering with Sears (in 1961), marketing their products under the Craftsman brand. This beneficial branding agreement lasted until the 1990s, giving the small manufacturing company the leverage to grow into an international giant.

With their initial success in the consumer generator market, Generac was able to expand rapidly. As soon as 1962, the company acquired a second garage. By 1965, Generac was entering the big leagues, with the construction of a 64,000 sq.-ft manufacturing plant and corporate headquarters near Waukesha, Wisconsin. Through the 1970s, growth was skyrocketing, with diversification into new markets, like chainsaws, power washers, and welders.

By the 1980s, Generac was in the perfect position to take on the commercial generator market. This started with the production of generators for the telecom market. Soon to be revolutionized by the cellphone boom. By 1989, the first automatic Generac standby generators were introduced for the home market. In 1995, the Jefferson plant in Wisconsin became the manufacturing hub for their domestic and RV generators, power washers, and welders. The following year, another manufacturing plant was built in Eagle Wisconsin. With another to follow in Whitewater, Wisconsin, in 1999.

In the early 2000s, Generac focused mostly on expanding and improving their standby generator models. With a specific emphasis on large industrial generators, the company embarked on developing groundbreaking innovations. Of these, the development of redundancy, through the use of parallel generators, and Bi-fuel (natural gas and diesel or gasoline combination) engines, were among the best new technologies implemented.   

In 2008, Generac tackled the portable and home backup generator market, with renewed enthusiasm. This involved new air-cooled engine designs, specifically for portable generators. In 2012, the company began it’s entry into the global generator market. Starting with the acquisition of Ottomotores UK limited, and various Latin American subsidiaries. Later, expanding into Europe, Africa, and Asia.

Generac continues to explore new technologies, especially in the field of home automation and integrated backup power solutions. Remote technology and battery banks of some of the many new and innovative products introduced by the brand in recent years.