ELECTRIC POWER GENERATORS FOR HOME USE

You probably know already that there are two basic types of residential power generators: stationary and portable.
Unfortunately, the numerous buying guides and articles available everywhere do not always emphasize the drawbacks and the issues associated with each of these types, so let's start with a little background information. Home electric generators include two main components: an engine and an alternator. That's why they are often called engine-generators sets or gensets.

Standby

(stationary) systems are permanently connected to your house wiring via a device called transfer switch and hooked up to a fuel source. Normally this would be the same source you use for the heating: natural gas, propane or diesel. The wattage of the air cooled standby systems intended for home use ranges from 6 kilowatt to 20 kW, so you can always select the right model that can supply your whole house including central a/c, sump pump, etc. In automatic mode such a system will start by itself without your involvement when it detects a power outage. Likewise it will shut down when utility voltage is restored.

Portable

devices range from 500 W to 17,500 W. When you need to use a portable genset, you have to moved it from the storage, fill with fuel or connect to a fuel source, manually start and than connect it to your equipment. There are no auto start portables. Gasoline and diesel models come with an on-board fuel tank, while propane models have to be connected to an external LPG tank. All the devices with an on-board tank require frequent refueling- at rated load their run time is typically 5-8 hours per tankful.
Both stationary and portable units can be run only outdoors. A stationary device sits outside just like a central a/c unit. A portable one is intended to be connected only when you need to use it.

PROS AND CONS OF DIFFERENT TYPES

As you realize, all types of gensets have pros and cons. Standby systems provide the highest level of comfort, but of course it comes with a price tag. Depending on wattage and options, complete systems with a transfer switch may sell from $2000 to $5000. You may also need to spend several thousand dollars for professional installation and fuel hook up. Before the installation, you will likely need to obtain permits for electrical wiring and fuel connection. You would also need to pass the inspections after the work is done. All this, obviously, takes time. So, if you are looking for a home generator because there is a hurricane or an ice storm in the next week's forecast, a standby type is not for you. Another issue is service. A hard-wired appliance that weights 400-500 pounds is not something you can easily disconnect and ship back or bring to a repair shop. Should you need a repair, you'll have to wait for a service technician to come to your home or for the manufacturer to send you a replacement part.

Portable generators are much cheaper-- their prices start at around $120 for 1000W model. Unlike stationary devices, they don't have to be hardwired to your house unless you choose to-- their control panel has several outlets of various types into which you can plug cables from your electric loads. This can be both an advantage and a disadvantage. On one hand, you can start using a portable unit, so to speak, right out of the box. However, this would work only if you want to run just stand-alone appliances, such as refrigerators and window a/c. You can just unplug them from the wall outlets and connect via extension cords to the generator. However, when it comes to lights, central a/c, boiler controls, sump pump and everything else that is hardwired directly into your house electrical lines, you'll face problems powering them up. This is something homeowners often don't realize and dealers may neglect to mention to you. You might ask, why can't I just hook up my genset to a wall outlet? First of all, it is illegal and dangerous to connect any power source into any electrical wiring connected to the grid. By trying to energize your house you are also feeding voltage back into the utility lines. This may hurt line workers or your neighbors who may think the mains is down. Aside from this, unless you are the only one who lost power, you would actually be trying to power up all the neighbors houses who lost electricity. This would likely overload your generator and trip its circuit breaker. Because of all of the above, if you want to run your built-in appliances and lights from a portable backup source you still need a transfer switch. In this case it has to be a manual one. This connection method is the safest one, but you would still have to deal with the professional installation, permits, inspections, etc.

You would also have another hurdle to overcome if you buy a portables model equipted with GFCI. The GFCI will trip when you use it with a regular transfer switch. This is something the manufacturers and retailers may not always tell you. If you choose a model with GFCI, you need to buy a special 3-pole transfer switch or otherwise discounnect genset's ground wire in the transfer switch. In any case, such a setup is still cheaper than a stationary one because portables cost less than standbys and manual switches cost less than automatic. In case of emergency, if you have no choice and you really need to connect your genset into a wall outlet, first flip the "disconnect switch" on the main service panel. This would isolate your house from the outside lines. This is not a recommended method though. You also need to remember that a standard outlet is rated for 15A. So, you can't use it for more than 120x15=1800 volt-amps. If you draw a higher current you may overheat the socket and the wires, which is a fire hazard.

SO, WHAT GENERATOR DO I NEED?

Well, buying the right model for the home involves several key decisions:
How much power do you need?
How soon do you need to use it?
How often do you expect to use it and for what duration of time?
Are you able to move around a few hundred pound device?

Here is when you definitely need a standby home generator system:

• Your house requires more than 17 kW power, or
• You want to be prepared for long-term power outages, or
• You want fully automatic operation, or
• You don't want to move around a heavy device.

Here is when you should buy a portable genset:

• You need emergency power immediately;
• You are looking to spend less than $2,000 (maybe even a few hundred dollars).

In all other cases, either type might work for you. You just need to choose between cost and convenience.
For standby gensets, my pick is the Generac Guardian® series available in the range from 8 kW and 45 kW. For my advice on portables, see best portable generators for home use.

Whatever genset you choose, remember that all engine driven devices have a common disadvantage- they all require maintenance, such as periodic oil change. If you don't feel like getting involved into this, you may want to consider a maintenance-free battery backup solution, such as a solar powered generator.