When I took over purchasing for our company in 2020, one of my first big projects was sourcing a standby generator. We're a 120-person manufacturing facility in Woodstock, CT—losing power means losing production time, and that gets expensive fast.
I looked at two main brands: Kohler and Generac. After managing quotes for three different generator projects over the years, here's my honest take on the differences. This isn't about one being universally better. It's about figuring out what matters for your situation.
Why I'm Comparing These Two
If you're searching for a residential or light commercial standby generator, you're probably looking at Kohler and Generac. They dominate the market, and both have their proponents. The conventional wisdom is that Generac is more affordable and Kohler is more durable. But is that actually true when you run the numbers?
Let's break it down across a few key dimensions: upfront price, reliability, service availability, and total cost of ownership.
Dimension 1: Upfront Price
Generac: Typically 10-20% less expensive on the base unit. A popular 20kW Generac air-cooled model might list around $3,500–$4,000 before installation.
Kohler: Generally higher. Their 20kW liquid-cooled unit (a more common configuration for them) often starts around $4,500–$5,500 for the generator alone. The Kohler 20kW standby generator price we saw was around $4,800 for the unit itself.
My take: Generac wins on sticker price, no question. But that's the hook. The install cost is often the bigger variable. I've seen quotes for a full install range from $5,000 to $12,000 depending on site prep, transfer switch (needed for NEC compliance), fuel line runs, and local permitting. The cheapest quote I got once was $8,500 all-in. It wasn't from a certified dealer for either brand.
It's tempting to think you can just compare unit prices. But identical kW ratings from different vendors can result in wildly different outcomes because of installation complexity and fuel source—(more on that below).
Dimension 2: Reliability and Build Quality
Generac: Air-cooled models are the most common. They are reliable for typical residential use—power outages a few times a year, running for hours at a time. However, for heavier commercial or industrial loads, or for running the generator for days during an extended outage, the air-cooled engines can struggle. They run hotter and wear faster under sustained load.
Kohler: Kohler's reputation is built on their liquid-cooled engines, which they also use in their generators (they manufacture their own engines). Liquid cooling allows for more consistent operating temperatures, longer engine life, and better performance under heavy, sustained loads. They are more expensive, but they are built for the long haul.
The incident that changed my view: We initially went with a lower-priced Generac for one of our smaller buildings. It was fine for the first two years. Then we had a major ice storm in 2023 that knocked power out for nearly 36 hours. The Generac ran for the first 12 hours, then started to misfire. We had to bring in a technician. The time I spent coordinating that, plus the lost production time, was a headache I won't forget. The failure was partly due to a faulty voltage regulator—a known issue on some older models. I didn't fully understand the importance of engine cooling until that specific incident.
Note to self: always check the engine type and cooling system for the expected load profile. It's not just about kW rating.
Dimension 3: Service, Support, and Parts Availability
Generac: Because they sell so many units, parts are widely available—even at big-box stores. For a standard repair, a local HVAC or generator tech can often get parts quickly. This is a major plus. The downside? There are also a lot of non-certified techs. We had one who didn't properly torque the connections on our Generac install, causing a ground fault that took weeks to diagnose.
Kohler: Kohler's dealer network is smaller and more selective. In our area (Woodstock, CT), finding a certified Kohler dealer took a bit more research. The benefit is that those dealers are generally more specialized and will have technicians who know the product inside and out. The potential drawback is longer wait times for a specific repair if the dealer is busy, or if a part needs to be shipped. But Kohler's parts network is excellent for their generators.
What I learned: For routine service and simple parts, Generac is easier to work with. For complex repairs or warranty work, having a knowledgeable Kohler technician who knows the nuances of their controllers and systems is invaluable. Managing relationships with 8 vendors for different needs (as I do for our company), I can tell you that a reliable service relationship is worth more than a few hundred dollars saved on the initial quote.
Dimension 4: Fuel and Performance
Most standby generators run on either natural gas or propane. The fuel source affects performance and cost.
- Generac (especially 18-22kW air-cooled): Often highly sensitive to fuel gas pressure drops under load. The larger Generac models need a significant gas supply line to the house to maintain proper flow. Under-sizing the gas line is a common installation mistake I've seen. This can cause the generator to stop running under load, which is exactly when you need it most.
- Kohler: Their larger liquid-cooled models generally handle fuel pressure variations better. They have more robust engine governors and fuel management systems. This is less of an issue for smaller units, but for anything over 20kW, it's a real consideration.
One vendor told me the first quote is almost never the final price for ongoing relationships. That was true here—the more I learned about fuel requirements, the more specific my original quote needed to be.
Which One Should You Choose? (Scenarios)
Here's my practical advice, not a definitive 'this one is better':
- Choose Generac if: You have a typical suburban home, your budget is a primary concern, and you need a generator for short-term outages (a few hours to a couple of days). The ease of finding parts and a technician is a major convenience.
- Choose Kohler if: You have a larger home, a small commercial facility (like ours), or you expect extended outages (12+ hours). The investment in a liquid-cooled engine pays off in reliability and longevity if you are depending on it for critical operations.
- If you run a business: Honestly, for a business scenario like ours, after the ice storm incident, we ended up with a Kohler 20kW unit for our main facility. The higher initial price was justified by the reliability requirement. For our secondary building, we kept a well-maintained Generac. The key was making sure our total cost of ownership (including the cost of downtime) was accounted for.
Final Thought: It's About the Installer, Not Just the Brand
Regardless of which brand you choose, the quality of the installation is more important than the generator itself. A bad install will cause problems regardless of whether it's a Generac or a Kohler. Get three quotes for the installation. Verify dealer certifications. Ask for references. That $200 you save on a low-ball install quote can turn into a $1,500 problem when the generator fails at 2 AM during a snowstorm. (That specific scenario happened to a colleague—I'm not being hypothetical.)
Pricing data based on publicly listed prices from major online retailers and certified dealer quotes in Woodstock, CT, as of January 2025. Prices exclude installation, permits, and variable fuel line costs.
