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Generac GP15000E

*Est. $2320
November 2012
by ConsumerSearch
Generac 5734

  • Air-cooled engine
  • Low-oil shutdown, fuel gauge
  • Two GFCI outlets
  • Auto idle
  • Hour meter
  • Uses a lot of gas
  • Loud
  • Limited portability
  • Not CARB compliant
  • Mixed reviews about customer service
Where to Buy

The Bottom Line

Producing 15,000 watts and a 22,500-watt surge capability, the Generac GP15000E portable generator can easily power multiple houses, including heavy-duty air conditioners, well pumps and other machinery.


Powers a whole house. The Generac GP15000E earns kudos for its ability to power an entire home. One owner says at that he was able to power a full 4,200 square feet, including two 4-ton AC units, three full-size refrigerators and a well pump, as well as provide power feeds to two neighbors. "This generator started right up and ran the whole house no problem," writes another who used it for a 2-horsepower well pump, a 4-ton geothermal heat pump and a couple of freezers.

Although the GP15000E has plenty of power, it doesn't draw the same consistent praise for delivering smooth, clean voltage. One user noticed the lights in the house pulsing and checked the generator's output, which ranged from 118 to 124.9 volts. A minority of others report misfires and some "shimmying," and this model isn't recommended for use with delicate electronics.


Great connectability. The Generac GP15000E offers a respectable array of connection options, including four 5-20R outlets, two of which are ground fault circuit interrupters (GFCIs); two L5-30R twist-lock outlets; one L14-30R twist-lock; and a single 14-50R twist-lock outlet. It also has a single 12-volt DC outlet.


Hold your ears. In reviews, nearly everyone says this generator is loud. We found no data on what a typical noise rating might be, however, and Generac doesn't provide this information on its website.


It sucks gas. Generac estimates an average runtime of 12 hours at half load from a 16-gallon tank of gas. The GP15000E's idle control lets you adjust the engine to one of four speeds according to the load, which should reduce fuel consumption, but owners still say this generator is a gas hog.

"The only downside is the fuel burn rate. This thing sucks it down!" writes one at, who powered his house and provided feeds to two neighbors. Actual figures about burn rate are scarce. The most exact example, posted on, is also very conservative at about 1 gallon of gas per hour. This is on par with a smaller generator's fuel use and probably indicates a light load.

Ease of Use

It'll give you a workout. One user writes that his 105-pound wife can easily move this 363-pound generator around, but most agree that it's only marginally portable at best. The good news is that setup takes only about an hour and the generator starts easily, even in very cold temperatures.

That said, a substantial number of owners post concerns that this generator works poorly or not at all right out of the box. Sometimes it requires servicing after just a couple of hours of runtime. One user says at that the gas tank came without a pressure valve, and would swell up like "a balloon about to burst" during the day; it sprayed gas when he cracked open the cap.

The GP15000E is covered by a two-year warranty, but several owners complain about Generac's customer service. "VERY, VERY, bad customer service by Generac company," writes one at However, a couple of recent positive reviews say customer service provided replacement parts quickly, so the company may have made efforts to improve what many consumers say is a shortcoming.

Where To Buy
Generac 5734 GP15000E 15,000 Watt 992cc OHVI Gas Powered Portable Generator with Electric Start

 (21 reviews)
Buy new: $2,966.00 $2,399.00   6 New from $2,181.51

In Stock. Eligible for FREE Super Saver Shipping


Our Sources

1. Field & Stream

Review Credibility: Very Good Smith evaluates four portable generators, including the Yamaha EF2400iS, based on firsthand experience. He says the Yamaha is one of the quietest generators in this test group.

Review: Portable Power, Bruce W. Smith, February 2007

2. Camping Life Magazine

Review Credibility: Very Good Camping Life magazine evaluates five portable inverter generators suitable for camping and RVing, including the Yamaha EF2400iS, the predecessor to the EF2400iSHC. Based on a team's tests, editors report each model's wattage output, noise level, weight and operating time per tank of gas. They like the EF2400iS's control panel layout and say it's "amazingly quiet" to operate.

Review: Compact Generator Shoot-Out, Editors of Camping Life, June 7, 2006

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