Natural gas is often the practical starting point when suitable utility service is already at the property. Propane makes standby power possible where that service is unavailable and lets you store a defined fuel supply on site. The choice comes down to what can reliably supply your generator, what the installation requires, and how you will manage a long outage.
Generac’s residential standby units are configured for one fuel source—natural gas or propane. That does not mean a standard installation automatically changes fuels if one supply fails. Generac’s standby FAQ explains the supported fuels. Any proposed conversion or alternate supply needs a model-specific plan.
Compare the two fuel arrangements
| Planning question | Natural gas | Propane |
|---|---|---|
| Where does fuel come from? | The utility gas service at the property. | A tank filled by a propane supplier. |
| What needs checking first? | Available pressure, meter capacity, pipe route, and demand from other appliances. | Tank location, storage volume, cold-weather vapor delivery, and refill access. |
| What limits a long outage? | Continued utility gas availability and generator service requirements. | Usable stored fuel, other propane loads, delivery timing, and generator service requirements. |
| What costs belong in the quote? | Any utility upgrade and the gas connection work. | Tank purchase or lease, installation, regulators, piping, and fuel delivery terms. |
Do not choose from the kW label alone
A generator may have different electrical ratings on the two fuels. For example, the current G0073250 product page lists 22kW on propane and 21kW on natural gas. See Generac’s fuel-specific output ratings. A proposal should identify the fuel you will actually use and the output available on it.
That distinction matters most when a design is already close to its capacity. Ask whether the proposed system can start the largest motor while supplying the other intended loads. A larger number on the front of the brochure does not answer that question.
A tank with fuel can still have a delivery problem
On a typical vapor-withdrawal propane system, stored liquid must vaporize quickly enough to serve the connected appliances. Cold conditions and a low liquid level can reduce that capability. PERC’s Technical Pocket Guide, pages 9–10 explains why tank sizing includes temperature and withdrawal demand, not just gallons.
For a rural property, give the supplier the generator’s full-load demand along with the furnace, water heater, and other propane appliances. Ask for a winter delivery plan that accounts for a blocked driveway or several days of difficult travel. On an existing natural-gas property, ask the installer to identify any utility work before agreeing to an installation date.
Compare costs using the same outage scenario
A propane price per gallon and a gas charge per therm cannot be compared directly. First estimate each fuel’s consumption for the same intended electrical use. Then apply the relevant local rate, including variable delivery or utility charges, and compare the installed costs separately.
Use the model-specific fuel examples to understand the calculation. If you choose propane, the next decision is how much usable tank capacity the outage plan needs.
To discuss the fuel arrangement at your property, call Brite Generators at 270-223-6302 with your location, existing gas appliances, and any tank information you already have.
Connected guidance
Comparisons Related to Natural Gas vs. Propane for a Standby Generator
Continue exploring this Topic with Severe Weather and Tornado Outage Preparation. Then connect this decision to Portable Generator Safety: The Complete Guide and Generac Standby Generator Maintenance: The Complete Guide; those adjacent choices can change equipment, installation scope, operating readiness, and total ownership cost.