Portable vs. Standby Generators:
A Homeowner's Buyer's Guide

The three types: portable, inverter, standby

Portable generators are the familiar gas-powered units on wheels. You roll them outside, run extension cords, or plug into a professionally installed inlet. They power essentials — fridge, sump pump, a few lights — and cost the least up front. Downsides: they're loud, they burn through fuel, and someone has to be home to set them up in the storm.

Inverter generators are the quieter, more fuel-efficient cousins. They produce cleaner power (safe for electronics and computers), sip fuel, and run much quieter — great for tailgating, RVs, and running a few essentials during shorter outages. They cost more per watt than conventional portables and top out at lower power levels.

Standby (whole-house) generators are permanently installed outside your home, wired into your panel through an automatic transfer switch, and start themselves within seconds of an outage — whether you're home or not. They run on natural gas or propane, so no refueling in a storm. They're the set-it-and-forget-it option, and the most expensive one.

How much power do you actually need?

Generators are rated in watts, and there are two numbers that matter: running watts (what it can sustain) and starting watts (the brief surge to start motors — a fridge or sump pump can need 2–3× its running watts to kick on).

The right way to size: list what you must keep running. Typical essentials:

• Refrigerator/freezer: ~150–800 running watts (1,200+ to start)
• Sump pump: ~800–1,000 running watts (2,000+ to start)
• Furnace blower (gas heat): ~500–1,200 watts
• Well pump: ~1,000–2,000 running watts (3,000+ to start)
• Lights, phone chargers, WiFi: a few hundred watts total

Add up the running watts of everything you'd run at once, add the largest starting surge on top, and add 20% headroom. Most homes' essentials land in the 5,000–8,000 watt range — which is why 7,500W portables are so popular. Trying to run central AC, electric range, and dryer on a portable is how people buy twice.

Transfer switch vs. interlock kit

Here's the part that legally requires an electrician. To feed generator power into your home's circuits (instead of running extension cords everywhere), you need one of two devices:

Manual transfer switch: a separate panel wired next to your main panel. During an outage you flip selected circuits from utility to generator power. Clean, clearly labeled, and the safest option for portables. Installed cost is typically a few hundred dollars plus the electrician's labor.

Interlock kit: a mechanical sliding plate on your existing panel that makes it physically impossible for the main breaker and the generator breaker to be on at the same time. Cheaper than a transfer switch and lets you power any circuit in the panel (up to the generator's capacity). Must be a listed kit made for your specific panel — not a homemade workaround.

Fuel types: gas, propane, natural gas, dual-fuel

• Gasoline: available everywhere, but it goes stale in months, and gas stations lose power in big outages too. Store with stabilizer, rotate your stock.
• Propane: stores indefinitely, burns cleaner, and big tanks mean long runtimes. But propane has less energy per gallon, and you'll need tank storage space.
• Natural gas: unlimited runtime as long as the gas flows (it usually does during electric outages), zero refueling. Only practical for permanently installed standby units.
• Dual-fuel: runs on gasoline or propane — flexibility when one fuel is hard to get. A smart hedge in storm season.

Rule of thumb: if you want "start it and forget it," that's natural gas or propane on a standby unit. If you want affordable backup you manage yourself, that's a dual-fuel portable.

What professional installation involves

For a portable with a transfer switch or interlock, installation means: mounting an outdoor power inlet box, wiring it to the transfer switch or interlock breaker, labeling every backed-up circuit, and testing the whole setup under load. Typically a half-day to a full day of work.

For a standby unit, it's a bigger project: concrete or composite pad, gas line run by a plumber or gas fitter, electrical connection through an automatic transfer switch, permits, and inspections. Most standby installs take 1–3 days of coordinated trades.

Maintenance: the part everyone skips

A generator that won't start in a storm is an expensive paperweight. The maintenance list is short but non-negotiable:

• Run it monthly for 10–15 minutes under load — this is the single most important habit.
• Change the oil per the manual (usually every 50–100 hours of runtime, or yearly).
• Fresh fuel: stabilize gasoline, or run the carburetor dry before storage.
• Battery: standby units have a starter battery — check it yearly, replace every 2–3 years.
• Exercise mode: most standby units self-test weekly — make sure it's actually enabled.

What it costs (national ballparks)

These are national ballpark ranges, not quotes — local labor, permits, and your panel's condition move the numbers:

• Portable generator (7,500W class): roughly $800–$1,500 for the unit
• Inverter generator: roughly $1,000–$2,500 depending on size
• Transfer switch or interlock + inlet, professionally installed: roughly $500–$1,500
• Standby unit (whole-house): roughly $5,000–$12,000+ installed, depending on size and gas work

The honest math: a portable plus a proper transfer-switch install often lands under $2,500 all-in and covers the essentials. A standby costs 3–5× more and covers everything, automatically, whether you're home or not.