The two paths
Whole-house standby generator: permanently mounted outside, fueled by natural gas or propane, automatically starts within seconds when the utility power drops. Powers the whole house (or a critical-load subpanel) through an automatic transfer switch. Self-tests itself weekly.
Portable generator: wheeled unit, fueled by gasoline (or propane on some models), started manually by pulling a cord or pressing a starter button. Runs extension cords or plugs into an interlock kit. Requires fuel storage and manual operation each outage.
Side-by-side comparison
Installed cost
- Standby (Generac, Kohler, Briggs): [verify: $9,000-$18,000 installed for 14-24 kW residential; includes ATS, gas line, concrete pad, electrical, permit].
- Portable: [verify: $700-$2,500 for the unit; another $400-$1,200 to install a generator inlet + interlock kit at the panel].
Operation during an outage
- Standby: automatic. You may not notice the transition. Lights flicker briefly; everything comes back.
- Portable: manual. You go outside in the storm, pull the unit out of the garage, fill with gas, start it, route the inlet cord, flip the interlock at the panel, energize selected circuits.
Fuel
- Standby: natural gas (unlimited supply via city gas) or propane (sized tank, typically 250-500 gallons for multi-day capacity). No refueling during the outage.
- Portable: gasoline (you stored 10-15 gallons before the outage). Refueling required every 6-10 hours of runtime. Gas stations need power to dispense fuel — widespread outages can shut down nearby pumps.
Capacity
- Standby: 10-30 kW typical residential, enough to power the entire house including AC, HVAC, water heater, and pumps. 22-26 kW is the sweet spot for most southeast Wisconsin homes.
- Portable: 4-9 kW typical. Enough for furnace + sump pump + refrigerator + a few outlets. Not the AC. Not the well pump (which can be 2+ HP, requiring a large surge capacity).
Maintenance
- Standby: annual service required (oil, filter, spark plug, battery, transfer-switch exercise). The weekly self-test exposes failures early. About [verify: $300-$450/year] on a service plan.
- Portable: spec maintenance per manufacturer; engine oil every 50-100 runtime hours; carburetor goes bad if stored with stale fuel.
Safety
Both have safety considerations. Standby is professionally installed, inspected, and permanently sited 5+ feet from the house with proper exhaust orientation. Portable generators kill people every year in Wisconsin from carbon monoxide poisoning — never run a portable in a garage, basement, or any enclosed space, even with the door open.
When standby is the right call
- You have a well pump. Without backup, no power means no water at any tap. This alone justifies a standby for most rural Walworth County homes.
- You're often away. A sump pump failure when you're away can mean a flooded basement. A standby runs whether you're home or not.
- Multi-day winter outages are the threat. January ice storms knock out power for 12-72 hours in our region. A standby just runs.
- You have medical equipment or work-from-home that can't tolerate outages.
- You can do natural gas. Natural gas standby has effectively infinite fuel supply.
When portable is the right call
- Outages in your area are infrequent and short (under 6-8 hours typical).
- Budget is the binding constraint.
- You're home most of the time and can operate it.
- Critical loads are limited: furnace blower, refrigerator, sump pump, a few lights. No AC, no well pump.
- You have safe storage for the fuel and the generator itself.
What we install
We install primarily Generac and Kohler standby generators across the three-county area. A typical 22 kW installation includes:
- Concrete pad sized to the unit.
- Natural gas or propane line sized to the generators full BTU load.
- Automatic transfer switch (ATS) wired between the utility meter and the main panel, or to a critical-load subpanel.
- Permit pulled with the AHJ; final inspection.
- Initial commissioning, load test, and homeowner walkthrough.
- Recommendation for an annual service contract.
Action
- Schedule a generator sizing visit. Well do a load calc on your actual house and tell you whether a 14, 18, 22, or 26 kW is the right size.
- Read the panel upgrade article — some installations require panel space we have to make first.
