When you're shopping portable industrial generators, the first question is how much power you need to start and run your equipment. The four standby-style models here range from 20kW to 45kW and span diesel, propane, and NG/LP fuel, so your choice comes down to load, fuel availability, and whether you want new or used.
Quick Take
All four generators are standby units, not fuel-prone portable machines you carry around by hand. The new Generac Guardian 26kW brings the lowest listed price in the set and includes a 200A transfer switch plus Wi-Fi remote monitoring. The used Generac and Kohler propane units offer more output for a lower listed price than the new diesel Generac, which sits at the top of the price range. If you need to go diesel, the new diesel Generac is the only option here; if low hours are a priority, the Kohler's 541.5-hour meter is a notable point.
Listed Price Comparison
| Generator | Listed Price | Price Bar |
|---|---|---|
| Generac 20kW SDC020 Diesel Standby | USD 11,995.00 | |
| Generac 35kW Propane Standby | USD 4,000.00 | |
| Generac Guardian 26kW NG/LP Standby | USD 3,967.84 | |
| Kohler 45kW Standby (39kW Single Phase) | USD 4,500.00 |
Decision Matrix
| Generator | Output | Fuel | Condition | Standout Detail |
|---|---|---|---|---|
| Generac 20kW SDC020 | 20kW | Diesel | New, 0 hours | Sound enclosure, 100-amp breaker |
| Generac 35kW Propane | 35kW / 35 kVA | Propane | Used, 1,611.7 hours | Weatherproof enclosure, steel skid |
| Generac Guardian 26kW | 26kW | NG/LP | New | 200A switch included, Wi-Fi monitoring |
| Kohler 45kW | 45kW (39kW single phase) | Propane | Used, 541.5 hours | Ford industrial propane engine |
Product Notes
#### New Generac 20kW SDC020 Diesel Standby Generator 2.2 Perkins 120/240V Single Ph
This is the only new diesel generator in the comparison, and the listing describes it as a 2023 model with zero operating hours. It produces 20kW at 120/240V single phase, uses an 83-amp output with a 100-amp breaker, and includes a sound enclosure for quieter operation. The 1800 RPM engine speed is typical for this class, and the unit comes from a United States origin listing. The trade-off is the highest listed price in this set, and the 20kW output is lower than the used Generac 35kW and Kohler 45kW models. If you need diesel fuel and a factory-new unit, this is the one to consider.
#### Generac 35 kW Propane Standby Generator
This used Generac offers 35kW / 35 kVA output at 120/240V single phase, backed by a 1,611.7-hour meter and a propane-fueled Generac V6 Vortec industrial engine. The listing includes a weatherproof enclosure, output breaker, analog control panel, and steel skid, which makes it a ready-to-place unit for a site that already has propane. Used condition is the main limitation: the description notes normal cosmetic wear and surface rust on the exhaust, so you should plan for that if you go this route. It pairs a 35kW output with one of the lower listed prices in this comparison.
#### Generac Guardian 26kW Standby Generator NG/LP Wi-Fi Monitoring w/200A Switch
The lowest listed price in the comparison belongs to this new Guardian 26kW. It operates on either natural gas or LP, includes a 200A automatic transfer switch, and adds Wi-Fi remote monitoring through the Mobile Link app. The description highlights automatic startup within seconds of a power loss, a corrosion-resistant finish, and a 5-year manufacturer warranty. The listing also identifies it as a home backup and emergency generator, so it is oriented toward residential or light commercial use rather than heavy industrial duty. With 26kW maximum power, it can't match the 35kW or 39kW output of the used propane units, but it gives you new equipment and the convenience of dual fuel.
#### Kohler 45kW Standby Generator (39kW Single Phase, LP
The highest output in this set comes from this used Kohler. The model name says 45kW, but the listing specifies 39kW single-phase output at 120/240V, so the 39kW figure is the one to match against your load. It has 541.5 hours on the meter, which is lower than the used Generac 35kW, and it's driven by a Ford industrial propane engine. The weather-resistant, sound-attenuated enclosure is a plus for site noise. Its listed price sits between the lower-cost options and the new diesel unit. The downsides are the used condition and the fact that you're getting 39kW, not the full 45kW, at single phase.
Final Recommendation by Use Case
Choose the Generac Guardian if you want a new standby unit with dual-fuel NG/LP operation and the convenience of a transfer switch and monitoring included. Choose the Generac propane unit if you need high output from a used unit and already have propane fuel. Choose the Kohler unit if the highest single-phase output in the group is your priority and you accept a used condition. Choose the new diesel Generac if your site runs on diesel and you want a zero-hour unit with a sound enclosure, even though it carries the highest listed price.
