Review – Generac GP17500E (5735) vs Westinghouse 28,000W (WGen20000)

Welcome to our comprehensive review of the Generac GP17500E (5735) — a powerful 17,500 Watt Portable Generator. A few years ago this was the biggest generator on the market but times have changed and this model has become a bit of a dinosaur compared to what you can buy today — and for less money. Westinghouse has recently released a 20,000W (Run) generator for much less money. I compare the GP17500E with the Westinghouse WGen20000. I’m here to save you some money.

Now, don’t get me wrong, the Generac 5735 is a reliable workhorse with plenty of power. The problem is the same reason why you prefer to buy a new car rather than a car from 1986. New generators are easier to use, have better technology, are more fuel efficient, are lighter in weight and have advanced features that you don’t get with an older generator. Generac is a great brand but you end up paying a lot more because of the name. Incidentally, Westinghouse has been in business since 1886, so you can still buy a quality heavy duty generator at a reasonable price.

Generac GP17500E vs Westinghouse WGen20000

Now, let’s compare the old with the new. The Westinghouse WGen20000 has been engineered with all the features you could want. It’s ideal for either your home emergency backup or for the jobsite. It has a lifting hook an GFCI outlets. You get 28,000W of starting power and 20,0000W of running power. Besides all of the great features, and excellent build quality, the price is unbeatable with an MSRP of $3599, over $1000 cheaper than the Generac 5735. You can decide which one is the better value.

If you want to pay over $1000 for the Generac, then go ahead. There’s no justification for it considering what you get with the Westinghouse WGen2000. I’m impressed by the full lineup of Westinghouse generators. They’ve established their brand as leader in generator market. It’s hard to compete with them in terms of quality, durability and value. Having said that, I know that some people are brand loyal and they can’t be convinced to consider an alternative brand.

I have no loyalty to any brand. I gravitate towards brands that make the best generators, and put an effort into designing them for visual appeal. The entire package matters, and in the end, the price you pay determines if it’s worth it, and if it’s a good value or not. The choice is yours. My job is to present the facts, sprinkled with my opinion.

►Read our full review of the Westinghouse WGen20000, the most powerful portable generator on the market.

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Video : A Walkaround of the WGen2000

Intro / Generac GP17500E (5735)

In the world of portable generators, the Generac GP17500E is a legend whose prime has passed it by. It stills a solid generator but there are some new kids on the block that represent a new generation of generators. The GP17500E is 390-pounds, and it’s not something that you’ll easily move around. It has large pneumatic wheels and handles that make it easy to push – like a wheelbarrow. So, yes, it is portable. When you look at its power output, the Generac GP17500E can rival some of the built-in standby generators that you can only use to supply emergency power to your home and never use it anywhere else.

You’re looking at 17,500W of running power and an incredible startup (peak) wattage of 26,250W. This is enough to supply power for a mid-sized (3-bedroom) house with virtually no compromise as to what electric equipment that you can use at the same time. For most contractors, the Generac GP17500E will allow you to work without any restrictions. Later in the article, I’ll give you an idea of what type of equipment and appliances you can supply power for when using this generator.

When you take a look at the price, the Generac GP17500E loses its appeal in 2023. We first wrote this review about five years ago and it’s amazing how much the generator market has changed. One would expect to pay quite a few thousand dollars for a generator of this size. When you take into account the wattage that you’re getting from this generator and its robust build quality, it makes sense it’s fairly expensive but not more expensive than newer more powerful generators. As a comparison, we’ll take a look at two other generators that come at a similar price. The other two generators that I’ll be reviewing are both cheaper than the Generac GP17500E, but neither have the same out wattage that you’ll get from this giant of portable power generation.

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VIDEO / A Closer Look at the Generac GP17500E

The GP17500E was designed for situations where high-power demands are commonplace, such as a jobsite, home emergency backup, or for “preppers,” and those who choose to live off of the grid. Nowadays you can’t rely on your power to be there when you need it, especially in places like Texas or California where rolling blackouts have increased in frequency in recent years.

The power grid is aging and unable to handle the entire population turning on their air conditioners during a heat wave, or in winter and it’s freezing outside, when everyone turns on their heating. Basically, when you need power the most, it might not always be there. This is precisely why portable generators have increased in popularity in recent years. All I can say is be prepared for the inevitable power failures. Battery generators are an excellent clean alternative, and they are capable of powering your entire home, or smaller power stations designed to keep your essentials powered during a power outage.

We have a lot of options for power backup nowadays and we all benefit.

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These are the three portable generators that we will be focusing on in this review.

• Generac GP17500E – 17,500 running watts; 26,250 peak watts
• CAT RP12000E – 12,000 running watts; 15,000 peak watts —- DISCONTINUED
• Generac GP15000E – 15,000 running watts; 22,500 peak watts

These are all very powerful and capable portable generators. The Generac GP17500E is the most expensive of the three. But, as the most powerful, it works out at the best value. When it comes to your buck per watt, the CAT RP12000E becomes the most expensive. While the CAT is the cheapest, it provides the lowest peak and running watts. Many people, particularly contractors, may see the sense in paying more for the CAT brand. This is a truly respected name in the construction industry.

While the CAT brand carries a lot of weight, the Generac generators seem, from first impressions, to be robust machines with a solid frame and a decent, powerful engine. Though, after going through many customer reviews, it seems that under heavy-duty working conditions, the Generac generators don’t always fare too well. I’ll conclude from this, that the two Generac models in this review are great (especially in terms of value for money), though might not hold up to heavy-duty daily use. If you intend running your generator day in and day out, every day of the week, the CAT is probably the best option.

VIDEO | Learn more about Generac’s OHVI engine design

For homeowners who want to provide backup power during an outage and use it for powering an RV, I would highly recommend either of Generac models. They might not be quite as tough as the CAT but offer exceptional value for money and can handle quite a lot. For contractors that don’t need to run the generator continuously for weeks, this is also a great option

In the end, you won’t find a portable as powerful as powerful as the Generac GP17500E. At least, it’s the only portable generator that I’ve found to have a running wattage of more than 15,000W. This makes it a unique generator and is certainly worth its modest price.

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Review : Generac GP17500E (5735)

Running watts = 17,500W / Peak watts = 26,250W — 992cc gas engine. Best heavy-duty industrial generator.

Features:

• Generac’s OHVI engine incorporates full pressure lubrication with automotive style spin on oil filter for longer life engine.
• Idle control reduces noise and conserves fuel for extended run-times.
• Hour meter tracks maintenance intervals.
• Low-oil pressure shutdown automatically safeguards engine from damage.
• Large-capacity fuel tank with incorporated fuel gauge provides durability and extended run times.
• Hardened 1 1/4″ steel tube cradle for added durability and strength.
• Integrated lifting eye for easy transport and security on the job site
• Wheel Kit and lifting eye included
• Unit Weight : 390 lbs / 177 kg

Documents for the Generac GP17500E (Model 5735) Heavy-Duty Generator :

• View or download the MANUAL
• View or download the BROCHURE
• View or download the BROCHURE – GP SERIES
• View or download the TROUBLESHOOTING
• View or download the PARTS DIAGRAM
• View or download the MAINTENANCE

Outlets for the Generac GP17500E :

• 1) 120V 20A 5-20R Duplex
• (1) 120V 20A GFCI 5-20R Duplex
• (2) 120V L5-30R 30A TwistLock
• (1) 125/250V 30A L14-30R TwistLock
• (1) 125/250V 14-50R 50A Straight Blade
• (1) 12VDC 10A

Overview

In the introduction, I mentioned that the Generac GP17500E is the only generator in its class, being the most powerful gas-powered portable generator on the market. This makes it the best portable generator to provide power for the entire home during an emergency. It has all the features and a spec level to compare with any of the best generators that are available today. The Generac brand is owned by Briggs & Stratton, a respected US company that’s been delivering quality power products since before most of our grandparents were born.

The 992cc OHVI engine looks like a really reliable engine. It has a cast iron cylinder a runs very well. It also uses pressurized lubrication – it has an oil pump which not all small engines do. Like any decent modern engine, it will shut off if the oil pressure drops too low. It also has a low idle setting that will reduce noise levels and fuel consumption when there is no load on the generator. What really impressed me about this engine is the fantastic fuel consumption. It has an enormous 16-gallon fuel tank, something that one wants on a generator this big. At 50% load, you’ll get around 10-hours of run time from this generator.

If you’re using 50% of the rated power output, that’s 8,750W and very few houses will use that much power continuously for 10-hours, so you can expect to get around 12-15 hours for a normal house – using all the appliances and equipment that one usually would. Regardless of how many hours, or at what load is, the amount of kilowatts you get from a gallon of gas is way better than most of the generators I’ve seen. The Generac GP17500E produces a fuel consumption figure of 5.5 kilowatt-hours per gallon. I consider 4.75 to 5 kilowatt-hours per gallon to be really great for any generator. More than 5 KWh per gallon, well that’s truly fantastic.

The alternator is a true giant, to produce 17,500W running and 26,250 watts, it has to be. With an automatic voltage regulator and a large reserve capacity, you won’t experience any noticeable voltage changes, even when drawing a substantial load. You’re not going to get the perfectly stable sine wave that you would from an inverter generator, but there’s no need to worry about damaging your electronic equipment. The huge peak watt capability of the Generac GP17500E means that the voltage and frequency will always remain within a reasonable range for sensitive equipment like TVs and computers. The Total Harmonic Distortion (THD) for this generator is below 5% and that is generally what one can expect from the mains (grid) power.

Because this is a large generator, it has a 50A 120V/240V twist-lock outlet with a 2-pole circuit breaker. A 50A outlet is the biggest you’ll find on this type of generator but is nowhere near the total power output that this generator provides. If we ignore the massive peak watt capability and just concentrate on the constant running power output of the Generac GP17500E, we end up with a maximum amperage output of 145.8A at 120V or 72.9A at 240V. We can safely assume that in the average American home, you’ll be using both 120V and 240V if you’re connecting a generator like this through a transfer switch. You’ll probably be looking at a load that could reach 80-100A 120V/240.

If you’re reaching this kind of load, a 50A outlet simply isn’t going to cut it. This leaves you with one of two options. My first choice would be to modify it and use a 120A 120V/240V circuit. Very few people can do this themselves, you’ll need an electrician who knows what they’re doing to connect it up safely for you. The second option is to make use of the two 120V 30A outlets for your 120V needs and use the 50A outlet for your 240V circuits. This is going to add all sorts of complications to your transfer switch setup, you’ll need separate circuits for each outlet. Using the full power that this generator provides for site work isn’t going to be that complicated.

You can use any of the two 120V 30A outlets for high-power 120V tools, up to 50A for 120V or 240V and there are 4 standard 20A 120V outlets – two of which are GFCI protected. Each outlet has its own circuit breaker, so you won’t trip everything if there’s a fault on one. The Generac GP17500E also has 10A 12VDC outlet for charging batteries.

Other features that put this generator up there with top models is electric starting with a recoil starter as a backup. It has a digital hour meter to keep track of your service intervals and a fuel gauge on the gas tank. The entire generator is enclosed in a robust steel tubing frame and the 12” pneumatic wheels are equally tough. The frame doesn’t cover the top of the fuel tank so it doesn’t offer the same level of protection that you get from some of the other more industrial portable generators. I’m not that impressed with the handle either. It is easy to use and offers plenty of grip, but it doesn’t fold down like most others, so you’ll have this big handle jutting out all the time. Though it’s not really a big deal and the handle has rounded edges so you don’t need to worry about people getting injured if they bump into it.

It weighs a hefty 390 LBS, so you’re not going to be lifting it too easily. If you’re going to be transporting the Generac GP17500E, you’ll want to wheel it around and a set of truck ramps will come in handy if you’re going to be loading this generator onto a pickup.

Once you’ve taken all this into account and then look at the price of the Generac GP17500E, it’s hard to pass it up. You’re getting a remarkably impressive package for the money that you’re spending. So it’s not the same industrial type machine that you’d get if you bought the CAT or Honda equivalents, you’re still getting a high-quality generator with a 2-year warranty and it has heaps more power. In a nutshell – incredible value.

Visit the Generac site to learn more.

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Review : Generac GP15000E (5734)

15,000W = Running Watts / 22,500W = Starting Watts

Features:

• Generac’s OHVI engine incorporates full pressure lubrication with automotive style spin on oil filter for longer life engine.
• Idle control reduces noise and conserves fuel for extended run-times.
• Hour meter tracks maintenance intervals.
• Low-oil pressure shutdown automatically safeguards engine from damage.
• Large-capacity fuel tank with incorporated fuel gauge provides durability and extended run times.
• Hardened 1 1/4″ steel tube cradle for added durability and strength.
• Integrated lifting eye for easy transport and security on the job site

‎✔ View or download the BROCHURE for the Generac GP15000E (5734).

Overview

This is the model just below the Generac GP17500E and its normal retail price is little lower. Essentially, it’s the same generator with a smaller alternator which delivers a lower running wattage of 15,000W and a peak wattage of 22,500W. It looks the same as the Generac GP17500E and has all of the same features.

These two generators use exactly the same engine, the OHVI 992cc. This means that the smaller GP15000E has the same great fuel consumption of 5.5 kilowatt-hours per gallon that you’d get from the GP17500E. The only difference between them is that the GP15000E makes use of a smaller alternator – hence the lower output wattage. The alternator used in the smaller generator also has a great automatic voltage regulator (AVR), so you’ll get the same stable current (less than 5% THD) as you do from the Generac GP17500E.

It also has the digital hour meter and 10A12 VDC outlet that you’ll find on the Generac GP17500E, as well as a fuel gauge on the tank. Because all the components, with the exception of the alternator, are the same as the Generac GP17500E, it weighs almost as much. Though the smaller alternator has shed a few pounds from the overall weight of the generator, bringing this model down to 363 LBS. It’s still a heavy machine and even though it’s 27-pounds lighter than the GP17500E, it’s not going to be easy to lift. It has exactly the same wheels and handle as the Generac GP17500E so, in terms of portability, they’re just about the same.

Because the Generac GP17500E and the GP15000E are not all that different in terms of price, I would rather fork out those extra few dollars for the GP17500E and have more usable power. Though I’ve seen some amazing special offers on the GP15000E, something I haven’t for the GP17500E. I suppose it’s hard to convince people to buy a less powerful generator for almost the same price, so many retailers are discounting the smaller model. If you find the Generac GP15000E marked down to a price that is several hundred dollars less than the GP17500E then, I suppose it would make sense to go for the smaller generator if you want to save your money.

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And Lastly :

Review : DuroMax XP15000EH  (15Kw)

Powerful dual-fuel portable generator

The XP15000EH is not in the same power rating league as the other generators in this article but you do get 12,000W of running power, which is still a good amount, certainly this is at the higher end of the scale. One advantage you get with this DuroMax is dual fuel. Being able to run a 12KW generator off of propane is impressive.

The advantage of propane is that you can store it indefinitely whereas gas won’t last much longer than a year, even with fuel stabilizers. Storage is an imporant consideration if you’re buying a generator for emergency situations. If you don’t have fuel on hand your generator is useless. Whatever you buy, make sure you figure out a plan for a fuel source when the lights go out.

Features:

• Dual Fuel Technology allows Generator to be run on Propane or Gas.
• Powerful V-Twin DuroMax Engine accepts high demand with ease.
• Endless possibilities from Home Standby to Jobsites and RVing
• Equipped with Low Oil Protection the DuroMax V-Twin motor protects from mishaps.
• Easy Key Start allows anyone to start the unit with no problem!
• Multiple outlets allow for easy connection of multiple devices and tools.
• Heavy-duty lifting bar comes standard with Generator.
• GFCI Protected household outlets.
• Run Time Gasoline – Up to 10 Hours at 1/2-Load
• Run Time Propane – Up to 6 Hours at 1/2-Load on 40 lb. Tank
• Full EPA and CARB Compliance allows for operation in all 50 States

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Can you supply power to your entire home using the Generac GP17500E?

There are houses that will consume more than 40KW of peak power. These will be large homes with all the mod-cons, this would include the largest pool pumps, HVAC systems, and pool water heaters along with many other high-consumption electrical equipment. If you have a large high-end home that uses a lot of electricity and you want the entire electrical system to work when there’s a power outage, you’ll need to install a large standby generator to match the power demand. A system like this can cost well over $10,000 once you’ve taken the installation cost into account. Not many of us are going to spend that kind of money on a backup power system. Not to mention the gas bills, a large standby generator is going to glug down gallons of gas every hour and this is going to cost you.

For the average American home, you could easily live in complete comfort using the Generac GP17500E to supply emergency power. Whenever you use a portable generator to supply emergency power, you need to do your homework properly. Let’s face it, if the power is out for a few hours, or even a day or two, you won’t need to power everything that you would normally have working when the grid power is present. Your pool pump and heater, for example, are luxuries that you can do without in an emergency.

Stuff like running hot water and air conditioning is nice, but not essential. Fortunately, the Generac GP17500E gives a lot more power than any other portable generator and you should be able to keep the hot water heaters, AC, central heating furnace and other similar equipment working fine when on emergency generator power.

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Calculating your power needs

If you’re going to be connecting a generator to your home, you’ll need a transfer switch. There are many kits available and these will provide you with everything you need – the transfer switch that allows you to change between the grid and generator power safely, an auxiliary breaker box for generator circuits and all the cabling and plugs. While it’s possible to do this yourself if you have the electrical knowledge, it’s recommended to use a qualified electrician who’s experienced in this type of installation. Even if you do it yourself, you’ll need to get a certified electrician to come in and check the system and certify it. Local authorities require a certified electrician to sign-off on any electrical installation that affects the permanent wiring of your home.

Common Wattage Demands for Everyday Devices

As I mentioned when reviewing the Generac GP17500E, it’s going to require some extra thought as to how you’re going to utilize the full 17,500W/26,250W running and peak power output of the generator. Modifying the power outlet so that it can handle around 120A is going to mean that you have one transfer switch and a single auxiliary breaker box. Though this is not a standard off-the-shelf solution and you’ll be voiding your warranty if you modify the generator. Get an electrician who knows what they’re talking about to advise you and do the installation.

If you’re going to use the generator as is and make use the standard commercially available transfer switch kits, you’ll be using up to 3 transfer switch kits to make full use of the generator’s power output. The largest of these will be connected to the 50A outlet and the others to any of the 30A outlets.

After deciding exactly how you want the generator to be connected your home, you’ll need to select which of the existing circuits in your home you want to be connected to the auxiliary power distribution point – the transfer switch. If you’re using several transfer switches, you’ll want to spread the load evenly up to the maximum amperage of each transfer switch circuit. An electrician who understands these installations will do this for you. So you basically want to choose the circuits that need to be powered up during an emergency.

The Generac Brochure provides a few comprehensive and easy to follow tables that provide the running and starting watts for most household electrical equipment.

I’ll summarize some of the most important items that you’ll most probably be thinking of using:

• Lights (5-6 rooms with outdoor and security lighting):  1200W  / no starting watts
• Electric water heater (regular resistance heater):  2000W / 1000W starting
• Plasma TV and satellite receiver:    300W   / no starting watts
• Refrigerator or freezer:    700W /  2200W starting
• 0.5 HP sump pump:  1050W / 2050W starting
• Computer with 17” monitor:  800W  /  no starting watts
• 1000W microwave:  1000W / no starting watts
• 10,000 BTU central air conditioner:  1500W / 3000W starting
• Vacuum cleaner : 1100W  / 2200W starting
• Washing machine:  1150W  / 2300W starting
• Coffee maker:  1500W  / no starting watts
• Security system:  500W  /  no starting watts
• 0.5 HP door opener:  875W  /  2350 starting watts
• Toaster:  1200W / no starting watts
• Hair dryer:   1250W / no starting watts

Total power consumption:   Running Watts = 16125W  /  Starting Watts = 15100W

If we have all these appliances running simultaneously, the Generac GP17500E will have enough power to do this. If everything starts at once, the power demand will be 16,125W + 15,100W = 31,225W. So the GP17500E won’t be able to start every appliance on the list at exactly the same time – it has a starting peak watt capacity of 26,250W. The only time you have a situation where every appliance in your home starts up at exactly same time is when switch on the mains with everything in your home switched on. When transferring power from mains to the generator, it’s recommended that you switch each circuit on one at a time, this eliminates the possibility of the generator tripping form an excessive startup load. So it’s quite easy to manage your power and, with everything on this list running off the Generac GP17500E, the chances of the generator tripping are just about zero.

This gives you an indication of what you can do when running your entire home on the Generac GP17500E. Basically, you can continue your normal daily activities without thinking about how much load you’re placing on the generator. You can add more appliances to this list, you’ll just need to consider which of these you’ll be using simultaneously. It’s very seldom (if ever) that every electrical appliance in the home is switched on at the same time.

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CAT RP12000E / DISCONTINUED – Reference

Running 12,000 watts / Starting 15,000 watts

Features:

• Powerful 670cc V-Twin OHV motor with pressurized oil system
• 12, 000 watts running / 15, 000 watts starting
• 11.7 hours of runtime on one tank of gas at 50% load
• Removable lifting eye and ergonomic design for easy maneuverability
• Large fuel tank and idle control for extra-long run times
• Class leading number of outlets powers more tools at one time
• All copper generator produces clean power (total harmonic distortion (<5%)
• EPA Compliant
• Low harmonic distortion generator (thd< 5%) with AVR
• 9 total outlets including 20A, 30A and 50A Receptacles
• Large fuel tank and idle control for extra-long run times
• Weight balanced design for easy mobility
• Custom heat shields protect you from burns
• USDA approved spark arrestor guards against accidental fires.
• Recessed sockets and water protected covers to keep outlets clean and dry.

✓ View or download the SPEC SHEET for the CAT RP12000E.

CAT Support Includes:

• 24/7 Call Center Support
• Multi-language Support
• Online Help Center
• Video Tutorials
• Tools and Maintenance Kit in Every Box
• 3 Year Warranty with Registration
• Authorized Sales & Service Center Support

Overview

I’m always one to sing praises when it comes to CAT equipment. These guys are the kings of hard-working construction site machinery. From earth-moving equipment to smaller stuff like portable generators, CAT builds machinery that’s going to handle these ultra-tough working conditions. For that, I take my hat off to the CAT RP12000E.

With 12,000 running watts and 15,000 starting watts, it won’t power up all the equipment that one can when using the Generac GP17500E. It’s still one of the more powerful portable generators that you can get. It’s about as tough as a generator can be with a seriously robust steel tubing frame that extends all the way around the gas tank and has a centrally positioned eye at the top for easy lifting. The fold-down handle is also super-tough and has a soft grip, making it easy and comfortable to move.

The 670cc OHV V-Twin engine is a masterpiece of modern engineering. It has a pressurized lubrication system, using an oil pump and has low oil pressure shutoff. Compared to the 992cc brute used to power the Generac GP17500E, this engine seems small. Make no mistake, this engine has the power it needs and the alternator is as close to perfection as you can hope for. The voltage range is superb with less than 5% THD, so it has the performance of the highest standard.

The fuel consumption is also among the best. It has a 13.2-gallon gas tank and this will give you 11.7-hours runtime at 50% load or 5.3 kilowatt-hours per gallon, which is only a fraction less than you’ll get from the super-efficient Generac GP17500E. Emission levels meet the strictest standards and the CAT RP12000E is CARB compliant. It also has the convenience of electric and recoil starters and an incredibly accurate fuel gauge.

The control panel is fantastic with LED backlighting to make things all the more practical. This panel is slightly recessed and sandwiched between two solid bars, another example of the rugged design that makes the CAT one of the best portable generators for construction sites. It has all the outlets that one wants on this type of generator – 4 X 120V 20A; 2 X 30A 120V; 1 X 30A 120V/240V and 50A 120V/240V – all with circuit breaker protection. It also has a 12V battery charging outlet (8.3A) and a multi-function LCD screen that provides all the relevant information on your generator’s running hours and performance.

From the rugged steel frame to the tough metal-rimmed wheels, the RP12000E displays its true CAT DNA. This generator is designed and built to work hard. It’s a CAT and that says it all. While it tends toward the higher end of the price range, you are paying for exceptional quality and durability. With a 3-year warranty, the manufacturers are confident that they’ve built one of the best portable generators in the world and many will agree with this.

Tech Specs

• Rated Power: 12000 Watts / Starting Power: 15000 Watts
• Engine Displacement: 670 cc
• Engine Type: OHV v-twin
• Engine Speed: 3600 RPM
• Recommended Oil: SAE30 / SAE30 / 10W-30
• Lubrication Method: Pressurized
• Automatic Voltage Regulation (AVR): Yes
• Starting Method: Electric
• Shutdown Method: Automatic Low Oil Level
• Run Time at 50%: 11.7 hrs