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A large enclosed backup generator installed outdoors
Backup power · Buyer's guide

Best home standby and home-backup generators

Home backup power falls into two groups: permanently installed standby generators that start on their own, and large portable generators you connect through a transfer switch. This guide compares both types using only manufacturer spec sheets. We have not tested these units.

Updated October 16, 2026By the Big Buy Brief editorsSpecs from manufacturersNot hands-on tested

Photo: U. S. Fish and Wildlife Service - Northeast Region, Public domain, via Wikimedia Commons

Below: our quick picks, a side-by-side comparison, a full rundown of each model, and a plain-English buying guide.

Quick picks

Compare at a glance

Swipe the table sideways to see every column.

Comparison of home generators
ModelTypeOutputFuelWarrantyPrice
Generac Guardian 24 kW (7210)Best whole-home standbyStandby, automatic24 kW LP / 21 kW NG
Most output		Natural gas or LP5-year limited (maker)Check price
Kohler 20RESCL 20 kWAlternative standby brandStandby, automatic20 kW LP / 18 kW NGNatural gas or LP5 yr/2,000 h limited (maker)Check price
Westinghouse WGen12000DFBiggest portable home backupPortable, transfer-switch use12,000 W gas / 10,800 W LP runningGasoline or propane3-year limited (maker)Check price
Westinghouse WGen9500DFMid-size portable backupPortable, transfer-switch use9,500 W gas / 8,500 W LP runningGasoline or propane3-year limited residentialCheck price

Highlighted cells mark the highest (or lightest) listed spec in this group, where the specs can be compared directly. Specs are from manufacturer pages, checked October 16, 2026. We link to retailers for current prices.

The full rundown

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#1 of 4 Best whole-home standby

Generac Guardian 24 kW (7210)

  • TypeStandby, automatic
  • Output24 kW LP / 21 kW NG
  • FuelNatural gas or LP
  • Warranty5-year limited (maker)
  • Includes 200 A whole-house transfer switch
  • Wi-Fi monitoring
  • G-Force 1000 engine
  • 120/240 V single phase

What stands out (from specs)

  • Can run most homes, including central AC (check your loads)
  • Starts automatically in an outage

Trade-offs

  • Needs professional installation, permits and a gas line
  • LP use is about 3.9 gal/h at full load (maker spec)

Best for: Homeowners who want hands-off, whole-house backup.

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Spec source: manufacturer page. Plain retailer links; affiliate links are coming soon.

Generac Guardian 24 kW (7210)Check price
Check price on Amazon
#2 of 4 Alternative standby brand

Kohler 20RESCL 20 kW

  • TypeStandby, automatic
  • Output20 kW LP / 18 kW NG
  • FuelNatural gas or LP
  • Warranty5 yr/2,000 h limited (maker)
  • RXT automatic transfer switch
  • OnCue Plus remote monitoring
  • CH1000 air-cooled engine
  • Kohler lists a newer 20RCAL model; compare both

What stands out (from specs)

  • Second major standby brand to compare against Generac
  • Remote monitoring included

Trade-offs

  • The spec sheet is for an older model; check the current 20RCAL
  • Professional installation required

Best for: Buyers who want a second standby quote from a different dealer network.

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Spec source: manufacturer page. Plain retailer links; affiliate links are coming soon.

Kohler 20RESCL 20 kWCheck price
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#3 of 4 Biggest portable home backup

Westinghouse WGen12000DF

  • TypePortable, transfer-switch use
  • Output12,000 W gas / 10,800 W LP running
  • FuelGasoline or propane
  • Warranty3-year limited (maker)
  • 15,000 W peak on gas
  • 10.5 gal fuel tank
  • 120/240 V output
  • A WGen12000DFc variant adds a CO sensor with auto-shutoff

What stands out (from specs)

  • Far lower upfront cost than a standby unit
  • Dual fuel

Trade-offs

  • Manual setup during each outage
  • Must run outdoors, away from windows (CO risk)

Best for: Homeowners who want serious backup without a standby install.

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Spec source: manufacturer page. Plain retailer links; affiliate links are coming soon.

Westinghouse WGen12000DFCheck price
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#4 of 4 Mid-size portable backup

Westinghouse WGen9500DF

  • TypePortable, transfer-switch use
  • Output9,500 W gas / 8,500 W LP running
  • FuelGasoline or propane
  • Warranty3-year limited residential
  • 12,500 W peak on gas
  • L14-30R and 14-50R outlets
  • Remote electric start
  • Transfer-switch ready

What stands out (from specs)

  • Two 240 V-capable outlets
  • Remote start

Trade-offs

  • Less output than the WGen12000DF
  • Same outdoor-only CO cautions

Best for: Running essential circuits (fridge, furnace blower, well pump) through a transfer switch.

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Spec source: manufacturer page. Plain retailer links; affiliate links are coming soon.

Westinghouse WGen9500DFCheck price

Buying guide

Standby vs. portable

Standby units start automatically and run on natural gas or LP. Portables cost less but need you to connect and refuel them during each outage. Both need a transfer switch or interlock installed by a licensed electrician.

Sizing

List your essential loads. Large motors (central AC, well pumps) need extra startup capacity. Generac and Kohler dealers offer load calculations; get more than one quote.

Carbon monoxide

Run portable generators only outdoors and far from doors, windows and vents. Install battery CO alarms inside your home. Consumer Product Safety Commission guidance applies.

Permits

Standby installs usually need electrical and gas permits from your city or county. In Chicago, check with the Department of Buildings.

Who we are

How we chose

We chose these models because they show up in current best-seller results at major retailers, come from established brands, and have full spec sheets published by their makers. We compared only what manufacturers publish and linked every source.

We have not hands-on tested these products. For lab results, see the independent testers below.

  • Every spec links to the manufacturer's own page.
  • No star ratings, invented scores, or copied retailer reviews.
  • No prices that go stale. Retailer links show today's price.
  • Commissions never decide the order. Disclosure.

By the Big Buy Brief editors
House Of Biz & Company, Chicago. We research specs, warranties and buyer questions. We don't claim hands-on testing we haven't done. Our method

Independent hands-on reviews

FAQ

How long can a standby generator run?

On a natural gas line it can run as long as gas service continues, though makers recommend scheduled maintenance. On LP, runtime depends on tank size and load.

Can I install a standby generator myself?

Generally no. Gas and electrical work usually needs licensed pros and permits, and makers may require authorized installation for warranty coverage.

Why no prices?

Installed cost depends on your home. Get local quotes. For portable units we link to retailers so you can see the current price.