The Generac SG100 is a 100-kilowatt industrial natural gas/propane standby generator — Generac's entry into the commercial gaseous segment that competes directly with the Kohler KG100 and Cummins C100 N6. While Generac dominates residential backup, their industrial gaseous line (SG series) targets the same commercial facilities as Kohler's KG line.
We encounter Generac SG-series units primarily at facilities that prioritized capital cost. The Generac industrial engine is reliable but parts are Generac-specific — unlike DSE-based platforms where third-party technicians can service the controls, the Generac Power Zone Pro requires Generac dealer tools for deep diagnostics. Service interval patterns are similar to Kohler KG: ignition system is the primary recurring maintenance item.
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Adjust load percent and tank size to estimate runtime. Pre-filled with this model's spec where available.
Estimate runtime on this tank
Fuel demand at 75% load
1,050,000 BTU/hr≈ 1050.0 cf/min @ 1,000 BTU/cf
On utility natural gas the runtime is generally unlimited provided the supply line and meter can deliver this BTU/hr at the engine's required inlet pressure (typically 5–14" WC residential, up to 5 psi commercial). Confirm against the OEM's published fuel-pressure spec.
Service intervals
Manufacturer-recommended intervals for the Generac SG100 under standby duty. Field intervals may differ based on load profile, ambient conditions, and fuel quality.
Oil & filter
Every 250 hours or 12 months
Spark plugs
Every 1500 hours
Major overhaul
≈ 15,000 hours
Load bank test
Every 12 months
Common failure modes
What we've seen fail on this platform. Use as a service-planning reference, not a diagnostic — actual failure modes depend heavily on duty cycle and maintenance history.
Component
Symptom
Typical hours
Severity
Spark plugs / ignition
Misfire under load, hard starting
1,500+
minor
Battery
Failed to start during outage
8,760+
minor
Coolant system
Overtemp, coolant loss
6,000+
minor
Frequently Asked Questions
How does the Generac SG100 compare to Kohler KG100?
Both are 100 kW gaseous standby at 1800 RPM. Generac uses their proprietary Generac industrial engine platform; Kohler uses their own turbocharged inline-6. Generac is typically priced 10-20% lower than Kohler. The Kohler KG100 has a turbo advantage (better power density); the SG100 uses a larger displacement NA engine for potentially longer service life.
Does Generac make their own engines?
Yes — unlike Kohler (which uses third-party engines on some platforms) and Gillette (which uses PSI), Generac designs and manufactures the Generac industrial engine platform in-house for their industrial gaseous generators.
What controller does the SG100 use?
Generac's proprietary Power Zone Pro controller with digital metering, Modbus communication, and remote monitoring via Generac's Mobile Link platform.
100 kW gaseous-fueled commercial standby generator. Upper-mid-range industrial gaseous unit for larger commercial facilities on natural gas or propane.
300 kW gaseous-fueled commercial standby generator. Kohler/Rehlko 300REZXC large industrial gaseous unit for major facilities, paralleling applications, and campus power. Note: the 300 kW Kohler gas genset is sold as the 300REZXC, not as 'KG300'.