A whole-house generator protects your home from unexpected outages by automatically supplying backup power to your entire electrical system. Before you buy or install one, it's crucial to understand what's actually included in a package so you're not blindsided by hidden costs or missing components. Let's break down the components and what you should expect to pay.
What a Typical Whole-House Generator Package Includes
A standard whole-house generator package includes the generator unit itself, an automatic transfer switch (ATS), installation labor, and a permit. The generator is sized to match your home's power needs—usually ranging from 10 kW to 48 kW depending on your electrical load. The ATS automatically detects a power loss and switches your home to generator power within seconds, then back to utility power once it's restored.
Most packages also cover a basic inspection of your electrical panel and an assessment of fuel supply options (natural gas, propane, or diesel). Installation typically takes 1–3 days, depending on site conditions and whether your home already has gas or propane lines.
The Generator Unit Itself
The generator is the core component, and sizing is critical. A 20 kW unit costs roughly $5,000–$8,000 (equipment only), while a 40 kW unit runs $10,000–$15,000. Larger homes with central air conditioning, electric water heaters, and multiple large appliances need 30–48 kW units, which can exceed $20,000 before installation.
Fuel type affects both cost and convenience:
- Natural gas generators are cheapest to run but require an existing line or installation ($1,500–$3,000 extra)
- Propane generators need an on-site tank (propane storage tank costs $1,500–$2,500) and frequent refilling during outages
- Diesel generators are durable and fuel-efficient but noisier and more expensive upfront ($12,000–$25,000+)
Automatic Transfer Switch (ATS)
The ATS is a separate component that costs $1,500–$3,000 installed. It monitors your utility power 24/7 and triggers the generator within 10–50 milliseconds of an outage. This switch is essential for safety—it prevents your generator from back-feeding power into utility lines, which can electrocute utility workers.
Some premium packages include smart ATS units that can be monitored and controlled remotely via smartphone apps, adding $500–$1,000 to the cost.
Installation and Labor
Installation labor typically ranges from $2,000–$5,000 depending on your location and site complexity. This includes:
- Placement and foundation work (concrete pad or mounting structure)
- Fuel line installation or connection to existing gas lines
- Electrical wiring and panel modifications
- ATS installation and testing
- Final inspection and permitting
If your home doesn't have existing gas lines and you're choosing a natural gas generator, expect to add $1,500–$3,000 for gas line installation. Propane customers must also account for a new tank installation.
Permits, Inspections, and Warranties
Most generator packages include local building permits (typically $200–$500), though some contractors roll this into the labor cost. Final electrical inspections are mandatory and usually covered by the installer.
Warranties vary significantly:
- Equipment warranty: Most manufacturers cover 5–10 years on the generator engine
- Transfer switch: Typically 3–5 years
- Installation warranty: Usually 1–2 years of labor warranty from the installer
Extended warranties or maintenance plans (annual inspections, oil changes, filter replacements) cost $300–$800 per year.
What's Often NOT Included
Don't assume the following are covered without asking:
- Fuel tank installation (propane or diesel)
- Upgraded electrical panel service (if your panel needs expansion)
- Regular maintenance after the first year
- Propane or fuel at initial startup
- Noise reduction enclosures (another $1,000–$3,000 if desired)
Getting an Accurate Quote
When comparing quotes, ask each contractor for a detailed line-item breakdown. Legitimate providers can estimate your required kW capacity by reviewing your electrical panel, recent utility bills, and major appliances.
If you're evaluating multiple installers, Mercoly makes it easy to compare trusted generators and backup power providers in your area, review their offerings side-by-side, and check customer feedback—all in one place.
Frequently Asked Questions
Q: Do I really need a whole-house generator, or would a portable unit work? A: Portable generators are cheaper ($1,000–$5,000) but require manual setup, fuel storage, and can't power your entire home simultaneously. Whole-house systems are automatic and handle your full electrical load—essential if you have medical equipment, rely on electric heating, or want true peace of mind during extended outages.
Q: How often do I need maintenance on a whole-house generator? A: Most manufacturers recommend annual inspections and oil changes (every 100–200 hours of runtime). Monthly load-testing for 10–15 minutes keeps the system ready. Propane and natural gas systems require less frequent servicing than diesel units.
Q: How much will my monthly electric bill increase after installing a generator? A: A standby generator adds $10–$20 monthly to your utility bill if powered by natural gas or propane (for monitoring and engine exercise cycles). There's no increase if you use diesel with a fuel tank, though you'll pay when you refuel after extended outages.
Compare detailed generator packages from certified installers today to find the right system for your home.