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How Much Does a Whole House Generator Cost? Standby vs Portable vs Battery
A whole house standby generator costs about $6,000 to $11,000 installed on average, and $9,500 to $24,000 for systems over 20 kW or long gas and wire runs, according to HomeGuide. Generac puts the typical installed cost at $8,000 to $16,000 including the generator. A large portable generator with an interlock kit can back up most of the same circuits for a fraction of that, if you are willing to start it yourself.
Whole house generator cost breakdown
| Item | Typical cost |
|---|---|
| Standby generator unit only | $3,000 to $6,000 |
| Installation labor | $3,000 to $5,000 ($5,000 to $12,000+ for over 20 kW or long runs) |
| Automatic transfer switch installation | $600 to $2,500 |
| Concrete pad | $150 to $400 |
| Permits | $80 to $450 |
| Gas line | $12 to $25 per foot |
| Propane tank installation (if no natural gas) | $400 to $1,800 |
| Total installed | $6,000 to $11,000 ($9,500 to $24,000 for larger systems) |
Source: HomeGuide, "How Much Does a Whole House Generator Cost," written December 2025.
Standby generator price by size (unit only)
| Size | Unit price | What it typically covers |
|---|---|---|
| 7 to 10 kW | $2,000 to $3,000 | Lights, fridge, sump pump, well pump, microwave, TV, and furnace fan |
| 13 to 16 kW | $3,000 to $4,500 | Full home under 1,500 sq ft |
| 17 to 20 kW | $4,000 to $6,000 | Full 1,500 to 3,000 sq ft home |
| 22 to 25 kW | $4,500 to $12,000 | Full 3,000 to 5,000 sq ft home |
Source: HomeGuide. These are unit prices before installation. For reference, Generac lists its 22 kW Guardian (G0070420) at an MSRP starting at $6,119.
Ongoing costs: fuel and maintenance
- Fuel: Generac's spec sheet for its 22 kW Guardian lists propane use of about 2.53 gallons per hour at half load and 3.90 gallons per hour at full load. A 500 gallon propane tank holds about 400 gallons when full (tanks are filled to 80%, per AmeriGas), which works out to roughly 158 hours, or about 6.6 days, at half load.
- Maintenance: HomeGuide puts annual maintenance plans at $200 to $650.
The portable alternative: generator plus interlock kit
HomeGuide notes that portable generators cost $500 to $2,500, plus $400 to $1,300 for a transfer switch. An interlock kit with an inlet box runs $400 to $850 installed. Here is what that looks like with in-stock equipment:
| Setup | Equipment price | Running watts | Notes |
|---|---|---|---|
| DuroMax XP13000EH + interlock kit installed | $1,299 + $400 to $850 | 10,500 W (gasoline) | 14-50R outlet, dual fuel, electric start |
| DuroStar DS13000MXT + interlock kit installed | $999 + $400 to $850 | 10,500 W gasoline / 9,000 W natural gas | Tri fuel: gasoline, propane, or natural gas; CO alert |
| DuroMax XP15500HX + interlock kit installed | $2,299 + $400 to $850 | 12,000 W (gasoline) | Two 14-50R outlets, CO alert |
Equipment prices are from our product pages; installed interlock cost is HomeGuide's range. In total, that is roughly $1,400 to $3,150, versus $6,000 to $11,000 for an average standby install. The trade-off: you have to roll the generator out, start it, and refuel it yourself. Interlock kits for most panels are $49.95 to $69.95. See How to Hook Up a Generator to Your House for every safe option.
The quiet alternative: whole home battery backup
A home battery switches over automatically with no fuel, noise, or exhaust:
- Nature's Generator MyGrid 10K with 50 A automatic transfer switch: 10,496 Wh, 10 kW, 120/240V. $5,999.99
- Jackery Explorer 5000 Plus: 7.2 kW at 120/240V, expandable from 5 to 60 kWh. From $3,149, or $3,989 with the Smart Transfer Switch.
Batteries run as long as their stored energy lasts, so they suit shorter outages or pair with solar. Read Home Battery Backup: Cost, Sizing, and Is It Worth It?
Which is right for you?
| Standby generator | Portable + interlock | Home battery | |
|---|---|---|---|
| Typical total cost | $6,000 to $11,000+ | About $1,400 to $3,150 | About $3,149 to $6,000+ for the equipment |
| Starts automatically | Yes | No | Yes (with transfer switch) |
| Runs for days | Yes, on natural gas or a large propane tank | Yes, with refueling | Only with solar recharging |
| Noise and exhaust | Yes | Yes | No |
For sizing, start with What Size Generator Do You Need to Run a House? and How Many Watts Does a House Use?
Need a quote? Call 1-888-855-7286. Tell us your home size, panel, and fuel type, and we will price out a portable, battery, or hybrid backup setup.
Whole house generator cost FAQ
How much does a whole house generator cost installed? About $6,000 to $11,000 on average, and $9,500 to $24,000 for systems over 20 kW, per HomeGuide. Generac says $8,000 to $16,000 including the generator.
How much does a 22 kW generator cost? Generac lists its 22 kW Guardian at an MSRP starting at $6,119 before installation.
What is the cheapest way to power a whole house in an outage? A large portable generator with an interlock kit. The DuroStar DS13000MXT ($999) plus an installed interlock ($400 to $850) comes in around $1,400 to $1,850.
How much does it cost to maintain a standby generator? About $200 to $650 a year for a maintenance plan, according to HomeGuide.
How long will a 500 gallon propane tank run a whole house generator? At Generac's 2.53 gallons per hour (22 kW, half load), the roughly 400 usable gallons last about 158 hours, or about 6.6 days.