Skystream Specification Data Sheet

Skystream 3.7 Power Curve

Skystream 3.7 Energy Curve



Simple & Dependable

The Skystream 3.7 ia a simple and dependable wind generator for those considering the purchase of a residential wind turbine. Its aesthetically-pleasing style was designed specifically for maintenance-free, grid-tie use without the need for expensive batteries. The Skystream 3.7 wind turbine simply converts available wind energy into clean, nonpolluting power for your home’s energy use and any excess power is supplied to the power-grid. Depending on the local utility and state requirements, any excess electricity produced by a residential wind turbine will be sold back to the utility and/or provide an energy credit that you can use at a later date.

Unique Features

Included with every Skystream 3.7 wind turbine is a true sine-wave inverter fabricated as part of the unit’s head making it a true, compact, grid-tie wind turbine. Since there is no external inverter there is nothing to attach to your home except a small disconnect switch that is usually required by the power company. The electrical cable routes from the wind turbine to the breaker panel and is connect through a 240VAC, 20 amp breaker. Once connected, the on-board inverter senses the 240 VAC, after a 5-minute wait, and your wind generator is ready to start producing power. Every time the wind blows, the power inverter will convert the available wind-energy into clean, green power. With the Skystream 3.7 there are no worries about connecting to the power grid. The wind turbine’s inverter is UL certified to UL-1741, (Skystream 3.7 UL Certificate of Compliance,) In fact Federal regulations require utilities to allow connection of renewable energy devices to the power grid under the Public Utility Regulatory Policies Act of 1978 , or PURPA.

Another great feature of the Skystream 3.7 is the ability to rotate effortlessly as the wind changes direction. As the air moves across blades the turbine rotates away or points from the prevailing wind. That's because the Skystream 3.7 is a down-wind turbine. Note that it does not have a wind-vane to keep it pointed into the wind, rather, it points away from it (180 degrees). The most notable benefit of a down-wind configuration is the reduced sky foot-print, like the large, commercial wind turbines. With a small foot-print, the Skystream 3.7 wind generator is less noticeable to discriminating neighbors.

Coupled with the small sky foot-print, the Skystream 3.7 is design for quite operation. The generator's unique arched blades significantly reduce the “whipping sound” inherent to typical windmill blade designs while at the same time efficiently increasing its ability to capture available wind energy. As far as sound levels are concerned the wind turbine generates less than 60 db (noise). Please see the attached noise report below. In a nut shell, the Skystream 3.7 noise generation is significantly less than an outside air conditioning unit.

Skystream 3.7 Sound Report

Safety Features

The Skystream 3.7 was designed with safety in mind, safety of personal property and safety to the turbine (self preservation). The on-board computer constantly monitors the turbine’s operations to ensure the most power is provided for the available wind energy and the generator is operating with prescribed parameters. For instances, under normal operating conditions the generator will increase speed as wind conditions change until it reaches 325 rpm or at a wind speed of 19 mph. As winds increase above 60 mph (or 360 rpm) the on-board computer will assume storm conditions and shut down for one hour. After that it will restart and resume normal operations unless the they exceed the 60 mph threshold, where the cycle will repeat. The Skystream 3.7 shuts down to prevent damage from over-speed conditions. It also reduces the risk to personal property by ensuring it does not come apart.

Another safety feature is the ability to shut itself down in the advent of a power grid failure. The Skystream 3.7 on-board computer constantly monitors the power grid to ensure there is a constant 240VAC (most application will use the 240VAC configuration). If there is a loss of power the wind generator will shut itself down regardless of the available wind energy and will not resume operations until the utility power grid is restored. This is called anti-islanding and it is a safety requirement (National Electrical Code, NEC) that all grid-tied inverters must include in order to prevent high voltage remaining on the grid after a utility power failure. It is also a requirement to the UL 1741 certification.



Backup Power For most installations there is no need to purchase a separate true sine-wave inverter because the Skystream 3.7 is a grid-tie wind turbine. However, for those who require a backup supply of energy when the power grid fails, a separate inverter is required. The Skystream 3.7 is only capable of generating a 240 VAC pure-sine power for energy produced within the wind turbine. The figure below shows a typical AC coupling configuration with a Skystream wind turbine connected to a subpanel. From the subplanel an OutBack off-grid inverter, FX3048T for example, is used. An OutBack off-grid inverter will pass voltage (bi-directional) to and from the power grid. When the power grid fails, power will be supplied via the battery bank. In this configuration, the Skystream 3.7 is used either as a battery charger using the Battery Charging Controller Kit and a grid-tie inverter to supply excess power to the power grid.



Is The Skystream 3.7 Right For Me?

The most popular question people ask is the Skystream 3.7 turbine right for my home? The answer is “definitely” if ample wind-energy is available in your area! Most literature will state that your local winds should average 10 mph before a home wind turbine is worth the investment. Although this is a good rule of thumb” the answer may not be that easy. This is a tricky question and absolutes should not be assumed, such as stating the average wind speed in regards to a turbine’s usefulness. There are many areas where the average wind speed is less than 10 mph but can benefit from a residential wind turbine installation. For instance, the average wind speed of 10 mph means that sometimes it’s above 10 mph and sometimes it’s below; rarely is it always a steady 10 mph. The trick is to determine if there are times during the day when the average is at least 10mph for sustained periods. In many areas of the county this is the case but it does vary greatly. For illustration purposes, let say the average wind speed in a given area is 9 mph. However for 6 hours a day between 11:00am and 5pm the average is 19 mph with the remaining part of the day averaging only 5.6 mph. Energy production by installing a Skystream 3.7 in this example would provide approximately 11.4kW per day (see the table below).

Expected Energy Production/Wind Speed

Expected kWh Production/month	175	230	400	440	500	570	620	670	710	750	800
Average Wind Speed (mph)	8.9	10.0	11.2	12.3	13.4	14.5	15.6	16.8	17.9	19	20.2

If your motive includes reducing your carbon foot print, your turbine (in the example above) avoids releasing 513 lbs of carbon dioxide into the atmosphere everyday your generator operates! Comparing the energy output of your turbine to a solar array, a 1.9 kW solar renewable system with a minimum average isolation (average available solar energy per day) of 6 hours is required. At $10.00 a watt for a solar array installation your cost is $19,000. A Skystream 3.7 turbine installation will fall somewhere in the $11,000 to $18,000 range. The cost difference for installing a turbine is driven mostly by the tower type and height.



There are two types of towers available for a Skystream 3.7, a monopole tower and a guyed tower. Both tower configurations work very well with the main driver being the installation cost, aesthetics, available height. The main point to remember with wind turbines is height is king. Generally speaking, height equates to more available wind energy, as you can see in the chart to the right. Guyed towers offer greater flexibility in the achievable height, generally cost less, and are quick to install. The down side is many people in residential areas are concern about tower aesthetics. Monopole towers on the other hand provide an aesthetically-pleasing tower without the guy wires. These towers more often than not are accepted by communities since they look similar to existing towers such as street lights and flag poles. Monopoles also require considerably less square footage than guyed towers. In fact, there are monopole wind-towers installed in San Francisco. Like any good news there is the bad or the downside. The major drawback is monopole towers cost more to purchase and to install. A major difference is the way the towers are mounted to the ground. With monopole towers, a large concrete foundation is fabricated along with steel “J” bolts to anchor the tower to the foundation. The concrete foundations have to be properly sized to ensure adequate support and loading of the tower/turbine combination. In a monopole tower configuration the entire load is transferred to the single foundation. In guyed tower configuration, the load is equally distributed among the guy wire support anchor points.



Summary

For most people the Skystream 3.7 wind generator is the right choice when considering wind power renewable energy. It will reduce your power bill and make a strong, visible statement concerning your commitment to a clean environment. Whether you decide to install monopole or a guyed tower, purchasing and installing a Skystream 3.7 may be the best investment you will ever make. The Skystream 3.7 price is cost competitive with you local power company and it’s a smart addition for new homes. Call Green Team Direct today and learn how easy it is to install your very own Skystream 3.7 and you too can enjoy Dependable Backyard Energy!