The PRO3.7E and GP3500iO are portable inverter generator offerings from Kohler and Generac, respectively. These two units push the bounds of inverted power delivery, so they’re great if you want the benefits of an inverter model but also need a lot of power. The Kohler generator produces 3,700 watts of surge power and 3,000 watts of rated power, while the Generac generator produces 3,500 watts of surge power and 3,000 watts of continuous power.
Although the engines these two generators are built around are fairly similar, the Kohler generator has a 3.4-gallon fuel tank while the Generac generator only has a 2.4-gallon fuel tank. Curiously, there’s only a one-hour difference in runtime – signaling that either the Generac is extremely fuel efficient or the Kohler is not very efficient. The latter seems more likely when comparing to other inverter generators on the market.
Where the Kohler shines is in the outlet panel. This generator is capable of switching between 120-volt and 240-volt power, while the Generac competitor is not. Both generators have a 30-amp twist-lock outlet, but the Kohler unit has two 120-volt duplexes, an additional twist-lock outlet, and a 12-volt DC outlet. The Generac model has a pair of USB charging ports, but these are less versatile than a single DC outlet.
Importantly, Kohler went above and beyond in protecting you against electrical hazards. The 120-volt duplexes are GFCI-protected, which you won’t find on the Generac generator. It also has an electric start feature, which is great for making the generator easier to use. Both models have an LED hour meter on the outlet panel so you can track your wattage output and fuel usage.
The only real downsides to the Kohler generator are weight and cost. The generator is 138 pounds, nearly twice what the Generac model weighs. However, Kohler did mount it on a set of burly wheels and attach handles to the steel frame. The Generac generator needs to be carried by hand by two people.
As for price, the Kohler generator retails for just over $1,000, compared to around $600 for the Generac generator. However, this seems very reasonable considering how many more features the Kohler model is packed with. For commercial users, getting a full three-year warranty from Kohler as opposed to a shortened one-year warranty from Generac may be reason enough to cover the price difference.