Off Grid or Not?

I'm shopping for rural property, and have looked at some parcels that are off the grid - some a short distance from utility lines and some a very long way. I don’t know a lot about solar- and wind-electric systems, and hope you can give me some guidelines to help compare the cost of installing and owning a system with the cost of utility line extension. When is staying off grid - or connecting to the utility - worth it?

Pete Little - Los Angeles, California

One of the main financial advantages to off-grid living is the lower cost of land. But if you want electricity at your remote property, be prepared to pay. Whether your money goes to a stand-alone RE system or to the utility to bring in a line will be up to you and what your end goals are. In some areas, the expense of line extension will be prohibitive, making your decision to stay off grid easier. But if connecting to the utility grid costs $5,000 or $10,000, your decision may be a little more difficult.

Your first step should be to examine your motivations and goals. While many people dream of being off grid, they often are not aware of the responsibilities and ongoing costs. In most places, utility electricity is inexpensive compared to making your own electricity off grid, and when there's any maintenance or troubleshooting, you just call the utility. Off-grid system owners must be prepared to take on the utility’s job, or pay someone else to do it.

So just how expensive is a residential off-grid electrical system? This depends on several factors, including incentives, the renewable resources available, and local installer pricing. But the biggest factor is the one only you can answer - how much electrical energy do you need? Here are some ballpark figures, and the resources to do your own analysis.

According to a Lawrence Berkeley National Laboratory study, the average house in your utility's service area used 5,900 KWH per year in 1999. Consider the cost of powering that average home with a PV system.

Using the PV output calculator (http://rredc.nrel.gov/solar/codes_algs/PVWATTS/), with default settings for Los Angeles, a system of 5 KW peak can meet the annual need, but you’ll have 47% more energy available in August than in December. Most off-gridders do not try to size their system to provide all of their electricity in the winter; instead they rely on a backup generator to make up for reduced solar electricity generation. This hypothetical homeowner may buy a smaller system that meets demand for a portion of the year, and rely more on the engine generator during the winter.

As a very rough approximation, I use a total installed system cost of $12,000 per KW peak for an off-grid solar system. So powering the average home in southern California would require an investment of about $60,000! Some incentives may apply, but few are applicable to off-grid systems (see www.dsireusa.org).

Fortunately, most off-grid homeowners manage to live well using much less electricity than the average homeowner. This is accomplished with a mix of energy shifting (using gas or propane instead of electricity), efficiency (Energy Star appliances and compact fluorescent lighting), and conservation (turning off lights, no central air conditioning, etc.). As a result, many off-grid households manage with a PV system that produces about 1,500 KWH per year. In California, this would correspond to a system of about 1 KW peak, or $12,000.

If your site is blessed with a good average wind speed or a flowing creek, a hybrid system is likely to cost less than an all-PV system. But the output of a wind or hydro system is very site specific, so I can’t be more exact.

The lack of utility access can save you money when buying land, perhaps enough to pay for your off-grid electric system, but you’re wise to "run the numbers" before you buy.

John Richter, Institute for Sustainable Energy Education - Bingham Farms, Michigan