The rated wind speed is the minimum wind speed of wind turbine when its power output reach the product announced capacity. In general, the rated wind speed of small wind turbine is in the range of 10 to 12 m/s.

If the axis of blade rotation is vertical to the wind direction, then called vertical-axis wind turbine (VAWT). If the axis of blade rotation is parallel to the wind direction, then called the horizontal-axis wind turbine (HAWT). Because the wind direction is essentially parallel to the land surface, so it also is used by blade rotation axis vertical or parallel to ground to identify the type of wind turbine.

In general, vertical-axis wind turbine is slower-rotation, lower noise and the power coefficient is smaller , the range of value is about 0.25 to 0.3. Horizontal-axis wind turbine is faster-rotation, higher noise and the power coefficient is larger, the range of value is about 0.3 to 0.35. Hi-VAWT wind turbines are highly efficient types of wind turbine in VAWT, their power coefficient are about 0.3. Hi-VAWT wind turbines have double advantages of high efficiency and low noise.

The power coefficient of wind turbine is the ratio of electrical energy that wind turbines can generate and the kinetic energy of wind before conversion. It’s an index to express power generation efficiency. In general, the power coefficient of small wind turbine is in the range of 0.25 to 0.35.

Based on energy conservation, the power coefficient is less than 1. However, energy conversion by wind turbine must satisfy the laws of fluid dynamics, according to the theoretical analysis of German physicist Albert Batz in 1919, the power coefficient of wind turbine is less than 0.593. The theoretical limit is ignored wind wake rotating and electromagnetic energy conversion losses, so the limit in fact is even lower.

The starting wind speed is the minimum wind speed of wind turbine when it’s starting rotation from stationary to continuous. The cut-in wind speed is the minimum wind speed of wind turbine when its power begin to output for rated load. Because wind turbine is designed to generate electricity, so the cut-in wind speed is more important. In general, the cut-in speed of small wind turbine is in the range of 3 to 6 m/s.

Because the kinetic energy of wind is proportional to the cube of wind speed, so in the very low wind speed the energy conversion of wind is very little. However, most of the time wind is generally not large in residential, so the starting of a small wind turbine is also an important feature.

Yes. All our DS Series are designed for both ground tower and roof tower installations. We have installed our DS-300Ws, DS-1500Ws and DS-3000Ws on regular house roofs, top of the buildings and even 35 floors of residential apartment.

We are strongly recommend you should always consult your local qualified structural engineer and civil engineer for an assessment of the site and check up your local government regulations as well before taking any further actions. Hi-VAWT does not take any responsbility for the assessment of suitability of roof installations