Generator Types: Standby vs Portable vs Inverter

Standby generators are permanently installed outside the home on a concrete pad, connected to the home's electrical panel via an automatic transfer switch (ATS), and supplied by a natural gas line or propane tank. When utility power fails, the ATS detects the outage within seconds and signals the generator to start. The generator reaches operating speed and the ATS transfers the electrical load to generator power, typically within 10 to 30 seconds. Sizes range from 10kW (essential circuits only) to 48kW or larger for whole-house coverage including central air conditioning. Brands include Generac, Kohler, Briggs and Stratton, and Cummins.

Portable gasoline generators are the most accessible form of backup power. They must be started manually and run outside the home (carbon monoxide risk makes indoor operation life-threatening). They power devices via extension cords or, with a manual transfer switch or interlock kit, selected circuits in the home. A 3,500 to 5,000-watt portable generator ($500 to $1,000) can power a refrigerator, several lights, a phone charger, and a window AC unit. Fuel consumption is significant: a 5,000-watt unit at 50 percent load consumes 0.5 gallons of gasoline per hour. Stored gasoline degrades after 30 days without a stabiliser.

Inverter generators produce clean power: less than 3 percent total harmonic distortion, safe for sensitive electronics including computers, televisions, and medical equipment. They throttle the engine to match the actual load, making them significantly quieter (50 to 60 dB at 23 feet) and more fuel-efficient at partial loads. The main limitation is output capacity: most inverter generators produce 1,000 to 7,000 watts. Two units can often be parallel-connected to double the capacity. Best for powering home offices and sensitive electronics during outages when a standby unit is not in the budget.

Natural gas standby generators connect to the utility natural gas supply line. The fundamental advantage is unlimited fuel: natural gas service is rarely interrupted during power outages. A natural gas generator can run for days or weeks without any intervention. Natural gas is also the least expensive fuel option, typically costing 50 to 75 percent less per kilowatt-hour of generated power than propane. Installation requires a gas line connection from the main to the generator location ($300 to $1,500 depending on run length).

Propane standby generators work identically to natural gas models from a performance standpoint. The difference is fuel supply: propane is stored in an on-site tank rather than drawn from a utility line. A 250-gallon propane tank costs $800 to $1,500 installed. A 22kW generator running continuously uses approximately 2 to 3 gallons of propane per hour. A full 250-gallon tank provides 3 to 5 days of continuous operation. Standard choice for rural homes without natural gas service.

Diesel generators dominate commercial and industrial standby power but are less common in residential applications. They are more fuel-efficient at equivalent output and have longer engine life under heavy continuous use. Diesel fuel stores better than gasoline but degrades after 12 to 24 months without treatment. Drawbacks for residential: cost ($1,000 to $5,000 more than equivalent gas units), noise (diesel engines are louder), and fuel storage requirements. In residential applications, NG or propane are almost always the better choice.