Portable Gas Generator VS. Standby Generator Cost Breakdown

First, let's define each of these generators.

Portable Gas Generator  This is a generator that you'll have to keep in storage until you need it.  When a power outage occurs, it must be taken out of storage along with an extension cord and plugged into an inlet receptacle hook up. This hookup will go on the outside of your house and will have a male connector (prongs that stick out, rather than holes you plug in to). It will connect to whichever panel system you installed inside your house. This setup is for powering a few appliances like a freezer, fans, or a T.V.

Automatic Standby Generator      This is a generator that automatically senses when the power goes out.  It has an automatic transfer switch that disconnects power from the utility line and connects to the generator.  It does this all within a matter of seconds.  This setup is for a more complete backup such as the whole house or several circuits.

Portable Gas Generator VS. Standby Generator
Cost Breakdown

Generac XG 7000E Portable Unit Spec Sheet

Generac Corepower 7KW Standby Unit Spec Sheet

A portable gas generator generally runs on gasoline.  It is possible to purchase one that runs on LP, but to keep this comparison simple, we'll stick with gasoline for now. We'll compare two generators of like wattage, one a portable and the other a standby unit.


A portable gas generator like Generac's XG 7,000E can run for around 10 hours on a 9 gallon tank of gasoline at 50% power.  That ends up being about $3.60 per hour. That is powering a few lights, freezer and a couple of refrigerators.  So an average power outage of 48 hours would cost you around $173 dollars assuming the price of gasoline is approximately $4.00/gallon. The cost of this unit is around $1300 which doesn't include a transfer switch or installation.
A standby unit, Generac's Corepower 7kw is similar in wattage.  It costs around $1899 which includes the transfer switch, but not installation.  When running at 50% load, it uses 2.41 cubic meters of natural gas per hour.  As this article is being written, natural gas costs about $4.59 per cubic meter.  This standby unit would cost $11.05 per hour to run which would be about $530 for 48 hours.

As you can see, a portable gas generator is more economical when looking at it from a monetary perspective.  However, you need to look at the entire picture.  Does it really make sense to store 45 gallons of gasoline for a 48 hour period?  Where would you store it and is it safe?  You could shorten your supply, but you can never be sure you'll be able to drive to the gas station at a moments notice to refuel.  You've also got to take into account the extra inconvenience it is to hook up the portable generator in inclement weather.  If you're not home, you have no way of knowing about an outage, so too bad.