When you're shopping for a portable industrial generator, the real decision isn't just about wattage-it's about what you're willing to manage in fuel, runtime, and price. These four used Generac standby units all deliver 120/240V single-phase power, but they range from $4,000 to $9,500, and each one makes a different trade-off. Here's how to sort through them.
Quick Take
The lowest-priced entry is the 35 kW propane unit at $4,000, but it carries 1,611.7 hours on the meter. If you need the highest output, the 50 kW diesel at $8,500 gives you a 271-hour generator with a 200-gallon tank. The least-used option is the 35 kW NG/LPG unit at $9,500 with just 110 hours. And if a smaller 15 kW load works for you, the 2016 SD15 diesel at $8,250 includes a 30-day functional warranty.
Price Comparison
| Product | Listed Price | Price Bar | Output | Fuel | Hours |
|---|---|---|---|---|---|
| Generac 35 kW Propane Standby Generator | $4,000 | 35 kW | Propane | 1,611.7 | |
| 50KW Generac Diesel Standby Generator | $8,500 | 50 kW | Diesel | 271 | |
| 35KW Generac Standby Generator | $9,500 | 35 kW | NG/LPG | 110 | |
| Generac SD15 15kW Industrial Diesel Standby Generator | $8,250 | 15 kW | Diesel | 334 |
All four generators are used, and all are configured for 120/240V single-phase output, which keeps the comparison focused on output, fuel, and runtime.
Decision Matrix
| Decision Point | Generac 35 kW Propane | 50KW Generac Diesel | 35KW Generac NG/LPG | Generac SD15 15kW Diesel |
|---|---|---|---|---|
| Output | 35 kW | 50 kW | 35 kW | 15 kW |
| Fuel | Propane | Diesel (200-gal tank) | Natural gas / propane | Diesel |
| Hours | 1,611.7 | 271 | 110 | 334 |
| Listed Price | $4,000 | $8,500 | $9,500 | $8,250 |
| Suits | Propane-friendly sites on a tighter budget | High-draw sites with room for a large tank | Low-hour, dual-fuel flexibility | Smaller loads where warranty matters |
Product Notes
Generac 35 kW Propane Standby Generator
This is the easiest way into 35 kW output without spending near the top of the range. The propane fuel source is straightforward for sites that already have a large LP tank, and the unit includes a weatherproof enclosure and steel skid. The analog control panel keeps things simple. The trade-off is the 1,611.7-hour meter, the highest runtime of these four, so plan for potential service needs. If you want 35 kW of single-phase output and propane is your fuel, this lower-priced unit gives you a clear path.
50KW Generac Diesel Standby Generator, 271hrs
If your site needs serious headroom, this is the only 50 kW option in the group. The 271-hour meter is the second-lowest runtime here, and the diesel fuel source comes with a 200-gallon tank, a meaningful convenience for longer runs. The limiting side is the price and footprint: at $8,500 it sits close to the top of the range, and the dimensions (89L x 37W x 64H) are substantial. It's a high-output workhorse for larger electrical loads.
35KW Generac Standby Generator, NG/LPG, 110 hours
This one is hard to ignore if you want a lightly used unit. At 110 hours, it has the lowest runtime of the four, a significant advantage when buying used. The dual-fuel capability lets you switch between natural gas and propane, giving you flexibility depending on what's available at the site, and the enclosure is sound-attenuated. The catch is the $9,500 price, the highest in this set. You're paying for that low hour count and dual-fuel flexibility, but if runtime matters most, this is a strong starting point.
Generac SD15 15kW Industrial Diesel Standby Generator
The smallest output of the group, but it comes with something extra: a 30-day functional warranty. If you need a diesel generator and your load requires only 15 kW, this 2016 model with 334 hours is a manageable size for smaller sites or backup roles. The price, $8,250, sits in the same neighborhood as the 50 kW unit, so you're allocating that money toward a lower output and the warranty. The limitation is clear: 15 kW won't handle large three-phase equipment or heavy starting loads, so it suits lighter single-phase needs.
Final Recommendation by Use Case
- Need the lowest entry price and propane is available: Choose the Generac 35 kW Propane Standby Generator at $4,000. You get 35 kW of single-phase output with a weatherproof enclosure; just plan for an 1,611.7-hour unit.
- Need maximum output and have room for a large diesel tank: The 50KW Generac Diesel Standby Generator at $8,500 delivers 50 kW, 271 hours, and a 200-gallon tank for extended runtime.
- Want the lowest runtime and dual-fuel flexibility: The 35KW Generac NG/LPG Standby Generator at $9,500 has only 110 hours and a sound-attenuated enclosure. It's the most expensive, but it's the freshest unit here.
- Need a smaller diesel generator and want warranty protection: The Generac SD15 15kW Industrial Diesel Standby Generator at $8,250 includes a 30-day functional warranty and 334 hours on a 2016 model for lighter loads.
