Rooftop wind turbines offer a relatively inexpensive way to participate in the rush to renewable energy. The principle allure is low installation cost. Typically, tower installations for larger turbines add 50-80% to the cost of the system. With a rooftop turbine, an $800 tower is replaced by a $39 roof mounted tripod, or a length of pipe attached to the side of the house.
According to Ron Stimmel of the American Wind Energy Association, “…rooftop turbines still account for only 1 percent or so of the 10,000 small wind turbines that are sold each year in the country.” For this reason, few performance statistics are available from actual owners.
It’s possible, however, to get an idea of the estimated power output of a rooftop turbine from the manufacturer’s website. For example, the Energy Performance chart for Southwest Wind power’s 200W Air Breeze predicts 20-30 kWh (kilowatt hours) per month from 10-12 mph winds occurring 6 hours per day.
To put this in perspective, 30 kWh is less than 5% of the power consumed each month by the average household. Overall, the payback from a single, roof mounted turbine in tangible financial terms leaves a lot to be desired; especially in light of the fact that unlike solar, there is no Federal tax credit for residential wind power.
But anyone thinking about installing a rooftop turbine(s) is probably aware of this already. The rooftop wind enthusiast is not motivated by financial relief, but rather the intangible rewards of pride of ownership, walking the walk, or simple satisfaction as a hobbyist.
Motivation aside, it doesn’t make sense on any level to proceed with a wind powered project unless the three following requirements are met:
1. Higher than average cost per kWh. The more you pay per kWh for electricity, the more economical wind power becomes. A rule of thumb in the wind turbine industry states a residential wind powered system shouldn’t be considered unless you pay $0.10 or more per kWh for electricity.
The easiest way to determine your cost per kWh is divide the current monthly balance on your electric bill by kWh usage (also plainly stated on your bill).
2. Building codes. Visit your building department to find out if there are any zoning restrictions for roof top turbines. Don’t build your rooftop system first and ask questions later – only to be told it violates zoning laws and must come down.
3. Minimum wind speed. Wind speed of 7 mph, or 3 m/s (meters per second) is the start up speed for just about every wind turbine. However, in order to get any “juice” out of the turbine, minimum wind speeds of 10-12 mph for 6 hours per day are necessary.
Although wind speed charts for the United States and Canada are available to help site larger turbines, they’re of little use for rooftop systems because the data is collected at a minimum altitude of 30 meters (98.4 feet).
However, you can get a good idea of the wind speed at proposed turbine locations by purchasing an anemometer (wind speed meter) for around $150. The kit comes with a rooftop sensor, 60′ of cable and mounting hardware for the read out display. These are not data logging meters, so you’ll have to keep notes on your observations.
If you’re really serious about wind speed data collection, you can purchase a data logging anemometer kit with tracking software for $400.
Depending on where you live, wind speeds generally fluctuate with the seasons. Readings taken during the hot summer months of July and August, when you’re begging for a breeze, are not usually a reliable indicator of average yearly wind speed.
Also, rooftop turbines located at the edge of a long flat roof experience much more wind than those located on roof peaks.
If, after a month or two of collecting data you determine there just isn’t enough wind for a rooftop wind turbine, you can always resell the anemometer and turn your attention towards solar.
Wind turbine ventilators are exactly as the name implies, they are a ventilator that is powered by the wind to create effective ventilation for different industries. This product works on wind assisted ventilation. Even just a little bit of wind can be just enough for the turbo ventilator to rotate.
When it comes to roof top ventilators they have several advantages as compared to the standard type of ventilator. Some of their many advantages include that they do not need to be powered by electricity, it does not cause any harm what so ever to the environment, it tends to save a lot of money because there is no operating cost, it is light in weight which makes this invention durable and easy to transport if necessary, plus it is almost maintenance free.
A great thing about this is that it is also available in different types of materials so they can suit different types of weather conditions. The two choices of the material are either aluminum or stainless steel. The size, number and installation all depend on different factors which include wind velocity, temperature differential, environment conditions, and the size of the building.
They have many different sizes of wind turbo ventilators that range from 16″ to 34″. Due to the fact that they are located at the highest point of the roof it is able to give off optimum ventilation. They also have to be strong and anti-corrosive. As they are installed on the top of the roof and would come in contact with rain and birds they had to make these machines rainwater and bird proof. They have also designed it in a way that prevents down draft into the building allowing air entry from the side openings.
Ultimately roof wind turbine ventilators are pleasant looking, and tend to enhance the architectural looks of the building or the house that it sits on top of.