A home wind system uses the available wind and breezes around a residence to rotate a small turbine that converts wind into electricity. These systems are becoming more popular in areas of the US where the wind and breezes are generally constant, and the wind speed (velocity) is typically between 8-35 miles per hour. Most small turbines have the capacity to turn into the direction of the wind to maximize the amount of electricity generated.
A small wind turbine system is recommended for homes when:
• There is enough wind where you live
• Tall towers are allowed in your neighborhood or rural area
• You have enough space in the home for the components (batteries, inverters, charge controllers, etc.)
• You can determine how much electricity you need or want to produce and if it works for you economically
• You have already reduced the energy load for your home
• There is sufficient space to allow for lowering the tower for maintenance.
Wind energy systems are most cost-effective in areas with plentiful wind resources (dependable higher wind speeds each day).
Reduce Energy Consumption
Before choosing a wind system for your home, you should consider reducing your overall energy consumption by making your home more energy efficient. Reducing your energy consumption will significantly lower your utility bills and will reduce the size of the wind turbine system you need.
For homes that are already energy efficient and utilize some types of natural heating, cooling, and daylighting, a small wind energy system can lower your electricity bill by up to 50%, and it is nonpolluting.
Wind turbines convert the kinetic energy in wind into mechanical power that runs a generator to produce clean electricity. The blades of a turbine are aero-dynamically designed to capture the maximum energy from the wind. The wind turns the blades, which spin a shaft connected to a generator that makes electricity. The turbine blades often resemble a ceiling fan (two to five blades) but newer models are available in creative egg and spherical shapes. The blades are typically made with combinations of plastic and metal materials that are flexible yet sturdy.
Parts of a Home Wind Turbine System
Many manufacturers of home wind turbine systems provide consumers with a complete package of all of the necessary components and assemblies.
The parts of a typical small wind energy system for a home include:
• The wind turbine: The turbine includes the rotor blades that spin when the wind is blowing; the alternator or motor which generates direct current (DC) power when the rotor blades are spinning; and the tail, which allows the turbine to turn in the direction of the prevailing breeze. Most small wind turbines generate 12, 24, or 48 volt DC power. The diameter of most home wind turbine systems range from 4 feet to 10 feet and generate power between 20 and 500 watts of power between 8 and 35 mile per hour of wind velocity (speed). Most small wind turbines have a tilt feature that turns the turbine slightly up or down during a severe wind or storm or a feature to turn off the turbine in order to protect the turbine from damage.
• The Tower: The tower is the support structure that holds the wind turbine at an ideal height, which is usually between 30 feet and 100 feet above the ground. Because wind velocity (speed) increases with the height above the ground, a tower should be as tall as is allowed by the local codes or zoning and available area surrounding the home. Shorter towers can be installed on a sturdy diameter pole or pipe, while taller towers are usually installed with a center pipe and guy wires. If a tower uses guy wires, the guy wires usually project from the center of the tower approximately 1/3 the distance of the tower height. Wind turbines are typically not mounted to the home roof directly. Some wind system companies make a tower structure that can tilt down to make accessibility easier for maintenance and repairs to the system. Towers are often located in areas where they will not damage nearby buildings or structures in case they collapse. Many codes discuss required clearance distances for towers.
• The brake: The brake is usually mounted on the turbine or the tower. The brake is a mechanical or electrical switch that allows the turbine to stop turning, even in a wind. This allows maintenance to be performed on the turbine in a safe way.
• The Inverter: The inverter changes the direct current (DC) power generated by the wind turbine into 120 volt alternating current (AC) power, which is the type of electrical power found in a residence.
• Disconnect: The disconnect breaker or switch is similar to the disconnect switch that is on a typical house. The purpose of the disconnect switch is to shut off the power to the house for safety or maintenance.
• Batteries (Battery Array): Whether the system is connected to the utility company grid or is a stand-alone system, a series of batteries (called an array) can store excess power for use in the home when the wind is not blowing. The battery array should be enclosed in a separate room that is ventilated to the outside as the batteries usually contain chemicals (such as acids) that may be hazardous. Batteries for the array are usually deep cycle batteries that be recharged over and over and are specially designed for wind turbine systems. Battery arrays wired in series (positive to negative) increase the voltage while arrays wired in parallel (positive to positive, negative to negative) increase the amperage. Most battery arrays are in multiples of six and are wired in both parallel and series.
• System Monitor: This device allows a homeowner to view the amount of power that the wind turbine system is generating versus the amount of power that is being used from the battery array or utility company.
• Charge Controller: The charge controller is connected to the battery array and the inverter. It controls the voltage and amperage of the electricity from the batteries to produce a constant power source that is free of power spikes or undercurrent. The controller also prevents the batteries from overcharging.
• Grounding system: The grounding system is a series of wiring and metal rods that penetrate the earth around the tower and turbine to protect the system from lightning strikes and other electrical hazards. A grounding system is required on wind turbine systems by building codes and utility companies.
• Wiring: The wiring system connects all of the components together. The wiring gauges (sizes) and types should be verified with the manufacturers of the wind turbine, controller, and inverter.
• Utility Meter: Depending on the requirements of your utility company, the meter is either the same meter that is connected to your utility company supplied power, or it is a separate meter connected to the utility company meter. For a single meter, the meter spins forward or backward, depending on whether the home is using the wind power or utility company power. On two meter systems, the extra meter spins forward to show how much power is generated by the wind turbine system. In either case, the utility meter is monitored by the utility company, and is used to determine your utility bill (or refund!).
Costs of a Wind Turbine System
Depending on the size of the turbine, the height of the tower, local building codes, utility company requirements, and the availability of the other components, a complete wind turbine system for a home typically ranges from $5-8 per watt of electricity generated.