How to choose a backup generator for your home

I have always thought about getting a backup generator for my home, but always thought it would be immensely expensive and complicated.

Considering that we don’t lose power very often it seemed like an unnecessary expense. What finally got me motivated was hurricane Irene. My area was heavily affected by the hurricane and we all lost power for days.

Luckily our house was fine and suffered no damage but with a young child, it wasn’t an option to stay home with no power and no refrigerator, air conditioning, etc. for days on end. We ended up staying at a hotel for three days until power was restored. When we got home we had to throw away about $500 worth of food from the fridge and freezer.

Doing the quick math, the hurricane cost us almost a thousand dollars cash simply because we had no power. Factor in the fact that we were uncomfortable away from home and living out of a suitcase. I suddenly realized that if I had spent a bit more than what the cost of the hotel and lost food were on a generator for my home, I’d have been able to stay home and live comfortably and normally waiting for the power to come back on while watching TV and surfing the internet with a glass of iced water on my own couch.

You basically have to look at owning a standby generator like buying insurance. You may feel silly for spending the money on it if you don’t need it for a while, but when you’re suddenly in a bad situation and everyone else is scrambling to find a place to go and watching their food spoil, you are comforted to know you thought ahead. As the Boy Scouts say: Always Be Prepared!

Generator Options

I started my research and quickly found that there are two main options for home backup generators:

Permanently installed standby generators and “Portable” generators. I put portable in quotes because the larger units are over 200lbs and require at least two people to put them in a truck. Portable is a relative term.

The good news is that thanks to the internet, research is much easier and you can get great prices online and stores like amazon.com give you free shipping even for the large generators that weigh hundreds of pounds. When I finally ordered my 220 pound generator, amazon shipped it to my door within two days for free!

Permanent Standby Generators

These are the Cadillac’s of generators. They sit proudly on the side of your house next to the air conditioner unit and are attached to your home power system. They constantly monitor the power coming into your home waiting for the power to go out. As soon as they detect the power is gone, they wait a few seconds to make sure it’s not a momentary blip then they fire up automatically and start powering your home.

Most of these units like the Generac Guardian 20,000 Watt Standby Generator are meant to power your entire home including heavy duty items like central air conditioning.

One thing to take into account when choosing a generator that runs off of natural gas or propane is that listed power of the generator is the amount of power it can generate when using propane. If you connect it to natural gas it will actually generate 5% to 10% less power because natural gas isn’t as efficient as propane.

So a 10,000 watt standby generator will probably only produce about 9,000 watts when using natural gas. This can be a big factor to consider if you will use maximum power when running your central air conditioner or other heavy appliances.

The three main benefits of a standby generator are:

- Fully automatic. You don’t have to do anything when the power goes out or when it comes back on.
- Fuel. Standby generators are usually connected to your home’s Natural Gas or Propane lines so you never have to refuel them. This can be a very big deal if your entire area has no power for many days (remember: gas stations can’t pump gas without power).
- Ample Power. These units are meant to be sized to power your entire home including large appliances and central heat and air conditioning. Literally living as if you are still on utility power.

The main drawbacks to a standby generator are:

- Cost. These larger units will generally run between $4,000 and $15,000 to buy and install. After you buy the generator, you will have to pay an electrician to connect it to your home and a plumber to connect it to the gas or propane lines. Standby generators need a foundation to sit on. Some come with a pad but some require a concrete pad be poured.
- Permanent. If you sell your house and move, it will probably not be cost effective to disconnect and take the standby generator with you.
- Maintenance. Generators are engines just like cars. They need periodic maintenance. With a standby generator you have to find a service company to come to your home to service it unless you are mechanically inclined to do it yourself.

Portable Generators

Portable generators are substantially cheaper and smaller than standby generators and give you a lot of flexibility. Most people that buy a standby generator store them in a corner of the garage or shed and pull them out when the power goes out or when they want to use them for portable power such as when camping or at a construction site.

Portable generators come in sizes ranging from 1,000 watts up to about 10,000 watts with the most popular models being in the 4,000 watt to 8,000 watt range. The Generac GP7500E with Electric Start can power a 3 bedroom ranch home’s systems, lights, and appliances and still have plenty of capacity left for niceties like TV and internet.

The three main benefits of a portable generator are:

- Portability. You can literally take it anywhere you need it. Portable generators store easily in a garage or shed and can be put in the back of your truck or van for use elsewhere or to take it in for service. You also have the option of lending it to a friend or family member if they lose power but you have not.

- Cost. Portable generators start as low as $200 and even the larger portable generators cost substantially less than permanent standby generators.

- Simple or no installation. Portable generators give you the option of just plugging in a couple of extension cords and running them into your house if that suits your needs. No need to hire an electrician or plumber

The three main drawbacks of a portable generator are:

- Fuel. You will have to buy and store a good amount of gasoline in advance since most gas stations can’t pump gas without electricity.
- Connection to house. Portable generators offer you two choices to connect to them: either standard extension cords which you will have to run all over your house to power your fridge and lamps or through a manual transfer switch which will have to be installed in  your circuit breaker panel beforehand. Check out my article on Installing a portable generator outlet on your home.
- Limited Power. The size of the portable generator you buy will directly determine how much of your house you can power with it. Even with a good sized portable, you will probably not be able to power your central air conditioner in addition to the other main systems in your house. Another problem is that the more power you draw from the generator, the higher the engine runs, which will make it use more gas. Just like your car, you can do 100mph, but you’ll use a lot more gas than doing 50mph.

Generator Considerations

In order to decide what generator type is the best fit for you, consider these points:

A permanent standby generator is a good choice if you:

  • Often lose power, whether for short or long periods of time
  • Live in an area that is always last to get power restored resulting in days of no power
  • Want the system to work automatically without having to follow a checklist
  • Want to have your entire home powered without having to worry about what you can turn on simultaneously

A portable generator is a good choice if you:

  • Rarely lose power and it is typically restored within a day or two when you do.
  • Want to provide emergency power to your home at lesser cost.
  • May move within the next several years and want to take your generator with you.
  • Want the ability to use the generator for camping or jobsites away from home.

Determining what size generator you need:

My needs for a generator were pretty easy to figure out, I live in a 1,200 square foot, 3 bedroom house. I wanted a generator to power my baseboard heat, fridge, lighting, and small appliances like TV. I will not use the dishwasher or washing machine when on generator power so I am able to power pretty much my entire house without the central air conditioner with a Generac 7,500 Watt Generator and still have plenty of power left over in case I want to use the microwave for a short time to heat up a sandwich.

One note to remember is that generators are usually rated with two numbers: Running wattage and Peak Wattage. Running wattage is how much it can handle continuously, whereas Peak wattage is how much it can handle in short bursts. For example, your fridge may run at 700 watts, but when you first plug it in, it may need 1,400 watts for a few seconds to get the compressor started.

The reason this matters is in the advertising. Some generators will say “2,000 watt generator”, but if you read the details on it, it’s actually 1,400 continuous watts with a 2,000 watt peak. When deciding what to buy, always use the running watts power of the generator to determine the power output. If you overload a generator, it will shut down until you reduce how much power you’re pulling from it.

Use a power estimate chart like this one to calculate how much power you think you’ll actually need. Keep in mind most CFL (spiral) light bulbs these days are between 11 and 14 watts. Also, if you use common sense with your generator and avoid using high wattage items like toasters and hair dryers, you’ll probably find you really don’t need as much power as you thought.

To keep from getting overwhelmed, just start with the basics that you know you’d need in an outage. Things like your fridge, a well pump, sump pump, furnace fan or baseboard heat circulator and some basics like cell phone chargers, AM/FM Radio, and  lighting like a lamp should pretty much cover it. Anything beyond that really gets into comfort which is fine, but if you’re on a budget you can get a less expensive smaller sized generator to cover the basics.

A couple of quick sizing examples:

 

 

This 1,400 Watt Portable Generator can power:

  • Refrigerator
  • AM/FM Radio
  • 10 CFL light bulbs (at 14W each)
  • Small TV
  • Box Fan

 

This 3,300 Watt Portable Generator can power all of the above, plus:

  • Central Heating Furnace Fan Blower
  • Computer with 17″ Monitor
  • Security System

 

 

 

This 7,500 Watt Portable Generator can power everything the two above can as well as:

  • Well Pump
  • Coffee Maker
  • Microwave
  • Video Games
  • Cable Box
  • Most of a small house (just making sure not to run high use items like coffee maker and microwave at the same time)

Once you get into the 10,000 watt range you can power pretty much the entire house including smaller central A/C systems. Anything larger will pretty much have you living the same as when off generator power.

Transfer Switch: what it does and why it’s a good idea:

A transfer switch is a small box that gets attached next to your circuit breaker panel and allows you to directly connect your generator to your house safely and easily.

If you opt for an automatic standby generator, it will most likely come with an automatic transfer switch that does everything for you. That’s about all you need to know about that.

If you go with a portable generator, it will not come with a transfer switch and is not required. A transfer switch like the Pro/Tran 6-Circuit Transfer Switchwill make your life on generator power much better and much easier. I’ll post a follow up article on transfer switches soon.

Bottom Line:

You WILL lose power. Whether it happens often or not and for how long will guide your decision on which generator to buy, but my recommendation is DO buy a generator. When you lose power and it’s freezing, the hotels are full and none of your friends or relatives have power, you will have immense comfort knowing you can start up your generator and keep your family safe and comfortable, turning an otherwise stressful and expensive problem into an inconvenience.

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2 Responses to “How to choose a backup generator for your home”


  • This is a well researched and presented article. Well done.

  • Thank You for your help, I knew nothing about generators and now I could have a conversation with any one, thank you again,
    I will be purchasing a portable generator with this information,

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