A standby generator quote covers an engine, two utility connections and a permit, and the connections are where the numbers move.
The components
The generator, by kW rating and by air-cooled or liquid-cooled.
The transfer switch, automatic, sized for the service and either whole-house or essential-circuit.
Load shedding modules and soft starters, where used.
The pad, composite or poured concrete, on a prepared base.
Gas piping from the meter or the propane tank, sized for the demand and the distance.
A meter or service upgrade from the gas utility, where the existing one cannot supply the additional load.
The electrical run from the generator to the transfer switch, and from the switch to the panel.
Permits — electrical and usually gas — and the inspections.
Where two quotes diverge
Distance from the gas meter. Gas pipe is priced per foot and it is sized for the run; a long run needs a larger pipe, which costs more per foot as well as more feet.
Whether the gas meter needs upgrading. A generator is a large gas load and many existing residential meters cannot supply it alongside the house. The utility's charge and lead time for that vary.
Distance from the panel, which is conductor and labour and sometimes a trench.
Whether a trench is needed and what it crosses — a lawn is one thing, a driveway is another.
Whole-house with shedding versus an essential-circuit subpanel, which changes the transfer switch and often the generator size.
Propane tank, if there is no gas service: the tank, its siting, the pad or the burial, and whether it is bought or leased.
What is often not in the base price
The concrete pad, where one is required rather than the moulded composite one.
Landscaping restoration after a trench.
A soft starter for the air conditioner, which is frequently what makes the quoted generator size adequate.
The first service, and the maintenance agreement.
A propane tank fill, which on a 500-gallon tank is a meaningful sum on its own.
Where spending more is worth it
A soft starter, which is cheap relative to a generator size step and often removes the need for one.
Shedding modules, same argument.
A slightly larger propane tank, because the cost difference is small and the run time difference is large.
Remote monitoring, which is standard on most current controllers and which turns a failed exercise cycle into a notification.
Where spending more is not
Generator capacity beyond the load list. A larger unit costs more to buy, more to install, and more to run, and it spends its life at a lower fraction of its rating where engines are least efficient.
Liquid cooling, unless the loads genuinely require it.
Comparing quotes properly
Ask each for the load list, the generator model and kW, the transfer switch type and rating, the gas pipe size and length, whether a meter upgrade is included, the pad type, and whether permits and the first service are included.
Two quotes that differ by a large margin almost always differ on the gas work or on whether a meter upgrade was allowed for, and that is a question with a factual answer the gas utility can give.
Timing
Dealers are overwhelmed after a major regional outage, and lead times for both equipment and installation stretch for months.
The households that get generators installed promptly are the ones that ordered before the event rather than after it. Prices are also better outside those periods, for the same reason.
Insurance and resale
Some insurers offer a small discount for a permanently installed standby generator, on the reasoning that it prevents frozen pipes and water damage.
At sale, a standby generator is a genuine feature in areas with frequent outages and close to invisible elsewhere. It is not an improvement that returns its cost, and in a storm-prone market it is one buyers notice.