Cost and sizing guide
Home generator installation
What a standby generator costs installed, how to size one to the loads that actually matter, and what the transfer switch, fuel and permit involve.
These are market ranges, not a quote. Generator pricing depends on the size the load calculation returns, the fuel available at the property, and where the unit can legally sit. Those three answers move the figure more than any option list does.
What a standby generator costs
Installed, most home standby systems land between six and fifteen thousand dollars. Roughly half of that is the generator, the rest is the pad, the transfer switch, the gas or propane connection and the electrical work.
| System | Installed range | Covers |
|---|---|---|
| Essential circuits, 10–14kW | $6,000 – $10,000 | Fridge, some lighting, furnace, a few outlets |
| Most of the house, 18–22kW | $9,000 – $15,000 | Above plus one air conditioner and a well pump |
| Whole house, 24kW and up | $14,000 – $25,000 | Everything, no load shedding |
| Portable with an inlet | $1,200 – $2,500 | Inlet box, interlock and a circuit; you supply and start the generator |
Sizing it properly
The instinct is to size for the whole house. That is usually the most expensive answer to a question nobody asked. What matters is which loads have to stay on, and what they draw at the moment they start rather than while they run.
Motors are the reason. An air conditioner or a well pump draws several times its running current for the first second. Size on running load alone and the generator stalls the first time the compressor kicks in.
A practical sequence: list what genuinely must run, add the running loads, then add the largest starting load on top. That number, not the square footage of the house, sets the generator.
Load shedding
A load management module lets a smaller generator cover a larger house by refusing to run two big loads at once. The air conditioner waits while the well pump runs. In practice you rarely notice, and it can drop you a whole size band.
Transfer switches
The transfer switch is what makes a generator safe. It disconnects the house from the utility before connecting it to the generator, so power cannot flow back down the line into someone working on it. It is not optional and it is not somewhere to save money.
- Automatic. Senses the outage, starts the generator, transfers the load, then reverses when utility power returns. Nobody has to be home.
- Manual. You flip it. Cheaper, and fine for a portable generator, but only useful if someone is there.
- Service-rated. Handles the main disconnect too. Often the cleaner install on a newer service.
Fuel
Natural gas, where the street has it, is the easiest: no tank, no refilling, no fuel going stale. Propane suits properties without gas service and stores indefinitely, but the tank needs siting and periodic filling. Diesel is standard on larger commercial units and rare on homes.
One thing people miss: a standby generator adds meaningful gas demand, and an undersized gas meter or line will starve it. That is worth checking before the unit is ordered, not after.
Siting and permits
Generators need clearance from windows, doors and vents, on a level pad, positioned so exhaust does not carry into the house or over a neighbor’s patio. Manufacturer clearances and local setbacks both apply, and the tighter one wins.
Installation needs an electrical permit, and a gas or plumbing permit where fuel is involved. Some jurisdictions in these counties also apply noise limits at the property line, which can decide where the unit goes.
Maintenance
A standby generator exercises itself weekly. Beyond that it wants an annual service: oil, filters, battery and a load test. The battery is the usual failure point, and it fails quietly, so the first anyone knows is the generator not starting during an outage.
Common questions
How long can it run continuously?
On natural gas, indefinitely, as long as the supply holds. On propane, it depends on the tank: a 500 gallon tank typically gives several days for a mid-sized unit at partial load. Manufacturers usually recommend an oil change after a long continuous run.
Is it loud?
A modern enclosed standby unit runs around 60 to 70 dB at a few meters, roughly a conversation. It is most noticeable during the weekly exercise, which is why we set that for mid-morning rather than early.
Can a generator run my air conditioner?
Yes, with the right sizing. The starting surge is what matters. A soft starter on the air conditioner reduces that surge substantially and can let a smaller generator handle it, which is often cheaper than the next size up.
What about a battery instead?
A battery is silent, needs no fuel and pairs well with solar, but it carries a finite amount of energy. It suits short outages and load shifting. For a multi-day outage with heavy loads, a generator still does what a battery cannot.
Do I need one at all?
It depends on what an outage costs you. A few hours a year is an inconvenience. Someone on a well, on home medical equipment, or working from home without an alternative is in a different position.
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