What are the pros and cons of going off the grid vs. a grid-connected renewable energy system?
Going off the grid offers complete energy independence — no utility bills, no grid outages, ever — but it takes some effort, and you will need to learn how to conserve energy. It is possible to produce enough energy with your own renewable energy (RE) system to live a fairly normal lifestyle, but one where every appliance is carefully evaluated for its energy consumption.
RE systems are not cheap (average costs of a PV system), and in many states, they are ineligible for tax credits, rebates and other incentives if they are not connected to the grid. Off-grid systems are also more expensive because you need to provide your own energy storage system in the form of batteries. Your battery bank will need to be large enough to cover your energy needs for whenever your energy resource — solar, wind or hydro — is unavailable. In addition, you will likely need an engine-generator to make up the difference and to maintain your batteries.
Your off-grid system will have a charge controller and monitoring equipment to help you keep track of your energy supply. You will have to assume the responsibility of being your own utility company’s manager — that’s why you have those monitors and a generator! If you use more electricity than you generate, then your system will shut down, preferably with a low-voltage disconnect feature to ensure that you don’t damage your equipment. If you run out, you can’t just borrow a cup or two from your neighbor.
Then there’s maintenance. Periodically, you will need to equalize, or overcharge, your batteries to keep them healthy. You may need to add water to your batteries on a monthly basis, depending on the type of batteries that you have. The deep-cycle batteries in a renewable energy system are not like car batteries, and they cost much more. If you aren’t the technical sort, don’t despair. For a price, most installers can set you up with a user-friendly system that requires less maintenance and has some automated features.
Finally, the biggest downside of being off the grid is that your system will produce less energy than a similar-sized grid-tied system for two reasons:
- Using storage batteries carries a very stiff penalty for losses in converting the electricity from direct current (DC) to usable voltages and alternating current (AC).
- Unlike with a grid-tied system, on sunny days, once all of your electrical needs have been met and your batteries are full, the excess electricity you could produce has nowhere to go.
If you have the grid available, the advantages of a grid-intertied RE system almost always outweigh the advantages of being off-the-grid. However, if you’re buying land, deciding to go off-the-grid can have some real benefits because property far from the utility grid is often less expensive.
If the utility line is nearby, the utility company can give you an estimate for how much it will cost to extend the line to your property — but you will find that after a half-mile to a mile, depending on the terrain, the cost of a renewable energy system may be the better bargain.
— Linda Pinkham, former managing editor for Home Power magazine.