Can I Go Off Grid Free Wind Systems
Hybrid Systems
Hybrid wind energy systems can provide reliable off-grid power for homes, farms, or even entire com-munities (a co-housing project, for example) that are far from the nearest utility lines. According to many renewable energy experts, a “hybrid” system that combines wind and photovoltaic (PV) technologies offers several advantages over either single system. In much of the United States, wind speeds are low in the summer when the sun shines brightest and longest. The wind is strong in the winter when less sunlight is available. Because the peak operating times for wind and PV occur at different times of the day and year, hybrid systems are more likely to produce power when you need it. (For more information on solar electric or PV systems, contact the Energy Efficiency and Renewable Energy Information Portal—see For More Information.)
For the times when neither the wind turbine nor the PV modules are producing, most hybrid systems provide power through batteries and/or an engine-generator powered by conventional fuels such as diesel. If the batteries run low, the engine-generator can provide power and recharge the batteries. Adding an engine-generator makes the system more complex, but modern electronic controllers can operate these systems automatically. An engine-generator can also reduce the size of the other components needed for the system. Keep in mind that the storage capacity must be large enough to supply electrical needs during non-charging periods. Battery banks are typically sized to supply the electric load for one to three days.
An off-grid hybrid system may be practical for you if:
- You live in an area with average annual wind speed of at least 9 mph (4.0 m/s)
- A grid connection is not available or can only be made through an expensive extension. The cost of running a power line to a remote site to connect with the utility grid can be prohibitive, ranging from $15,000 to more than $50,000 per mile, depending on terrain.
- You would like to gain energy independence from the utility
- You would like to generate clean power
Hybrid Power Systems Combine multiple sources to deliver non-intermittent electric power. A hybrid system that combines a wind system with a solar and/or diesel generator can provide reliable off-grid power around the clock.
Living Off-Grid: A Success Story
This home, built near Ward, Colorado (at an elevation of 9000 feet), has been off-grid since it was built in 1972. When the house was built, the nearest utility was over a mile away, and it would have cost between $60K–$70K (based on 1985 rates) to connect to the utility lines. The owners decided to install a hybrid electric system powered by wind, solar, and a generator for a cost of about $19,700. The parts of the system include:
- Bergey 1.5-kW wind turbine, 10-ft (3-m) diameter rotor, 70-ft. (21-m) tower
- Solarex PV panels, 480 watts
- 24 DC battery bank, 375 ampere-hours
- Trace sine wave inverter, 120 AC, 1 phase, 4 kW
- Onan propane-fueled generator, 6.5 kW rated (3 kW derated for altitude)
Electric appliances in the home include television, stereo, two computers, toaster, blender, vacuum cleaner, and hair dryer. The largest electric loads are created by a well pump and washing machine. The generator runs about 20% of the time, particularly when the washing machine is in use. Propane serves the other major loads in the home: range, refrigerator, hot water, and space heat. Solar collectors on the roof provide pre-heating for the hot water.
