Electrical power outages are unavoidable and increasing in both frequency and duration. Nearly 60 percent of all blackouts are caused by violent storms, but 34 percent are caused by equipment failure due to the nation’s aging and overloaded electrical grid. So what’s a homeowner to do?
One increasingly popular option is to purchase a standby generator, also known as a whole-house generator. These power-producing machines are your own personal electrical power source. Within seconds of a blackout, a standby generator will automatically kick on to power your home’s electrical circuits.
However, standby generators aren’t cheap and whether you should buy one or not isn’t an easy decision. Here, I’ll provide some detailed facts and figures, so you can decide if a standby generator is right for your home and family.
A Need-Based Decision
To a certain extent, whether or not you need a standby generator is strictly personal. To some, being inconvenienced by even a single blackout warrants getting a generator. But more often, need is determined by the likelihood of a power outage. If you live in an area with frequent (more than three times a year) or lengthy (more than several hours) blackouts, then a standby generator becomes more of a necessity than a simple convenience.
And once you’ve decided to get a standby generator, the next step is picking the right size generator.
Sizing Standby Generators
Generators come in lots of different sizes, and can be powered by either natural gas or liquid propane (LP). A common mistake is to get the largest unit available to power the entire house. And that’s certainly one option.
But a more sensible—and affordable—approach is to buy a generator sized to power your home’s most essential electrical circuits, such as those connected to the furnace, kitchen appliances, well pump, water heater, security system, garage-door opener, and a few lights and outlets. These installations are often referred to as “partial-house generators.”
House size is just one criterion for selecting a standby generator. The complexity of the home’s electrical system also plays a key role, especially if it has central air conditioning. So, sizing generators isn’t as simple as saying, “If your home has this many sq. ft., then you must get this size generator.” It’s slightly more complex than that, and an experienced electrician will calculate your home’s anticipated electrical loads and recommend the right size generator.
Standby generators are sized by kilowatts (kW), which is a unit of power. One kilowatt equals 1,000 watts. Therefore, a 22kW generator produces 22 kilowatts—or 22,000 watts—of electrical power. Each generator must also be matched to an automatic transfer switch (ATS), which serves as the brains of the standby-power system and tells the generator when to kick on and turn off. Again, the electrician will provide guidance here, but typically if the generator is connected to a 200-amp breaker panel, then a 200-amp ATS is required.
Ultimately the generator size will be based on the total running watts and starting KVA of all the circuits, appliances and mechanical systems connected to the generator. KVA is simply 1,000 volt-amps; a volt is electrical pressure, an amp is electrical current. Both of these numbers must be calculated: running watts represent the power consumed by an electrical motor while running normally, and starting KVA is required because each time an electrical motor starts up, there’s an extra electrical surge that the generator must be able to handle.
Sound and Service
Once the standby electrical circuits have been identified, the electrician will add up all the running watts and starting KVA to project the total electrical load for the entire system. At that point, the proper-size generator can be determinedCities often have noise ordinances restricting the installation of generators. A machine may be rated at 62 decibels, but that's often measured at 25 feet.
What does that sound like? Imagine a neighbor idling a Harley—tolerable in a rural environment but unacceptable in a tight city lot. Additionally, most building codes require generators to be at least 5 feet from a house opening and 5 feet from flammable materials, making urban installations tricky. Fuel-tank placement is almost always restricted, especially near parking lots and schools.
Also, generators need TLC like most complicated machines. Like cars, standby generators run nonstop for many hours, so they have to be maintained as if they were, well, cars. Generally, bigger units require more care.
"After 24 to 48 hours of continuous use, get it serviced," installer Pat Porzio says. "After around 10 days, have a professional change the oil and the filter."
Your generator will stay healthy through a lifetime of outages if you check the engine oil daily during use, run it at no more than 75 percent of its rated capacity, replace overworked or deformed motor brushes, and avoid starting or stopping it under load whenever possible.
A Costly Endeavor
There are many factors that go into determining the final cost of a standby generator, which makes pinpointing an exact price difficult. However, a good general rule is that the final installed cost is usually twice the price of the generator.
Also, be aware that there are two basic engine operating systems: air-cooled or liquid-cooled. Air-cooled generators are smaller and less costly, but they’re also louder than liquid-cooled models, even though liquid-cooled generators are typically larger.
Generally speaking, a 22-kW standby generator is suitable for a home that’s 2,500 sq. ft. or smaller, especially if the home is equipped with gas-powered heat and hot water and a gas range, all of which use very little electricity. A 22-kW air-cooled generator costs between $4,500 and $5,000, so the final all-in price would be approximately $9,000 to $10,000.
Large-capacity, liquid-cooled generators—in the 22kW to 45kW range—cost between $10,000 and $15,000, making the installed price approximately $20,000 to $30,000.
Regardless of which size or type of standby generator you choose, it’s a significant investment, but one that many homeowners are willing to make to keep their home and family safe and comfortable during the darkest of times.