10 Best Diesel Generators 2025 in the United States

The 20kW Standby Generator with 200amp Automatic Transfer Switch (ATS) from KOHLER offers robust power output and reliable performance, making it suitable for residential use. With the capability to produce 20kW using liquid propane and 18kW with natural gas, it delivers ample power to keep essential appliances running during an outage. One of its standout features is the automatic power restoration in just 10 seconds, ensuring minimal disruption during power failures.

The generator is equipped with advanced voltage and frequency regulation, safeguarding sensitive electronics from power surges. The versatile fuel option allows easy switching between natural gas and liquid propane, offering flexibility based on availability and preference. This model includes a 200-amp outdoor-rated automatic transfer switch, simplifying the installation process and providing a seamless transition during outages.

The KOHLER Command PRO engine is designed for durability, featuring hydraulic valve lifters that reduce maintenance needs and improve longevity. PowerBoost technology is another highlight, enabling the generator to handle large loads like central air conditioners without compromising power to other appliances. However, the generator's weight of 485 pounds may pose challenges for portability. Additionally, regular maintenance and service are crucial for its optimal performance. This generator is well-suited for homeowners looking for a reliable and powerful standby generator with automatic transfer capabilities and flexible fuel options.

The WEN DF1100T is a powerful dual-fuel portable generator that runs on gasoline or propane, delivering up to 11,000 surge watts and 8,300 running watts on gas, with slightly lower power on propane. Its flexibility to switch fuels with a simple dial offers convenience and backup fuel options. The 6.6-gallon gas tank supports about 8.5 hours of run time at half load, making it suitable for emergency or outdoor use. It includes electric start for easy powering up without manual effort, and the voltage can switch between 120V and 240V, fitting well with most home backup systems and appliances.

On outlets, it offers a good variety, including standard household plugs and heavy-duty connections, adding versatility. Weighing 214 pounds, it is less portable despite the included wheel kit, so moving it may require some effort. The noise level corresponds with typical generators of this engine size. This model does not include an automatic transfer switch (ATS), so manual setup during power outages is required.

Maintenance is straightforward with the included oil and a 2-year warranty, though servicing may require some basic technical knowledge. This generator is well-suited for homeowners needing reliable emergency power or for outdoor activities, balancing strong power output and fuel options, though it is somewhat heavy and lacks automatic transfer features.

The Westinghouse 28000 Peak Watt Home Backup Portable Generator is a robust option for anyone needing a reliable backup power source, particularly for residential use. With a peak output of 28,000 watts and running at 20,000 watts, it delivers significant power, making it suitable for larger appliances during an outage. The generator features an easy-start mechanism with a remote key fob and push-button electric start, which simplifies operation and adds convenience.

One of its standout strengths is the impressive run time of up to 11 hours at half load, thanks to the sizable 17-gallon fuel tank. This extended run time combined with its automatic low oil and carbon monoxide shutdown enhances safety and usability. Portability is manageable despite its 599-pound weight, as it includes reinforced steel handles, making it easier to move when necessary.

There are a few drawbacks to consider. While it offers multiple outlets for various connections, the generator can produce noise levels that may be disruptive, especially in quieter neighborhoods. Additionally, maintenance may be more involved due to its 999cc engine, which could be a concern for those unfamiliar with engine upkeep. Westinghouse backs this generator with a 3-year limited warranty and nationwide service, providing reassurance. Users looking for a powerful, versatile, and relatively easy-to-use generator for home backup will likely find the Westinghouse model meets their needs well. However, those sensitive to noise or with limited experience in maintaining large engines might want to explore simpler alternatives.