Living With a 12V DC Home Power System

Using 12V DC for home power requires some adjustments, but generating your own energy will protect you from rising utility rates.

| November/December 1984

Do you sometimes feel as if you're at the mercy of your mailbox and the monthly utility bill it contains? You're not alone: Power company per-kilowatt-hour (kwh) rates are pushing up over 15¢ in some parts of the country — enough to suck better than $100 out of many people's monthly budgets — and there's not the slightest reason to suppose we've seen more than the tip of this financial iceberg. Maybe it's just about time to abandon ship!

The alternative, a personal electrical system using a renewable resource, can offer an insurance policy against the inexorable escalation of utility electricity prices. Researchers such as Hunter and Amory Lovins (see A Tour of the Rocky Mountain Institute) have argued persuasively that investments in conservation and renewable energy are among the wisest anyone can make. But there are equally convincing arguments in favor of moving toward electrical independence — among them, the personal satisfaction you gain from taking control.

The power grid that public utilities and the government have built is a marvel of reliability, but that grid's awesome size and complexity make it hard to recall just how simple an electrical supply can actually be. A small, well-conceived 12V DC home power station need be no more complex than an automobile's electrical system.

In the following paragraphs, we're going to give you an overview of what we've found to be the simplest, least expensive method of achieving electrical independence. We've been working with low-voltage, direct-current power systems for a number of years now and have found that they offer a practical combination of low initial cost, expandability, flexibility, simplicity, and reliability. For people on a limited budget who are willing to conserve, low-voltage living is assuredly the most sensible way to cut the utility umbilical.

What Is Low-Voltage Living?

For our purposes, low-voltage means producing 12-volt direct current (VDC) and using it at that level whenever possible. For technical reasons, low-voltage electricity limits the size of a given appliance and the total amount of power that will be available in a day. Therefore, to keep the system simple, we've more or less arbitrarily decided that the largest 12-volt appliance we'll use will draw 150 watts and that the maximum amount of power that will be produced in a day is 3,000 watt-hours, or 3 kilowatt-hours (kwh). As you'll soon see, there are ways around both of these restrictions, but a low-voltage household will still end up being one that uses far less electricity than the norm of about 900 kwh per month.

Much of the margin between 900 kwh per month and 90 can be made up simply by not using electricity to power major heating appliances (a water heater, stove, or space heater, for instance). Solar energy is a good choice for water heating, gas or wood can be used for cooking, and passive solar heating — backed up with a little wood in the stove — should keep you comfy. Those three changes alone will trim at least 500 kwh/month from the U.S. average. But before we get too deeply into how to use electricity in a low voltage house, we'd better figure out where that power will come from in the first place.

5/5/2007 12:01:18 AM

Very well written article on 12 volt living. I have just moved into an alternative living arrangement and will be experimenting in the inventive realm by which I am hopeful to make a few alternative power break throughs. Come check out the place here - - you will be suprised at the current system I am sure. Scott

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