technical faqs

What are the dimensions?
quietrevolution wind turbines will come in three sizes, the first of which is the qr5 which stands 5m high by 3.1m in diameter and which is available now. Two further sizes are under development: QR12 (12m x 7m) and the QR2.5 (2.5m x 2.5m). Please note that these are the heights of the turbine only, the overall height will include the mast (normally 3.4m, 6m or 15m).

How much energy will the qr5 generate in one year?
On a good wind site the qr5 will generate around 4,000 to 10,000 kWh per year. This is equivalent to the electrical needs of a 15-20 man office (i.e. lights, computers, servers, printers, faxes and phones).

How is the qr5 power rated?
Peak Power at a windspeed of 14m/s is 7.4kW Aerodynamic or 6.2kW DC. BWEA Small Wind Standard uses a windspeed of 11m/s, using this the qr5 will be rated at 4.2kW Aerodynamic power or 3kW DC.

(N.B. When comparing turbine ratings please ensure that the wind speeds are like for like. Alternative manufacturers may not rate at the BWEA rating windspeed therefore comparisons should be made using the power curve.)

Is a power curve available?
Yes. It can be found on the latest product technical information factsheet.

What are rotor startup/shutdown speeds?
Cut-in condition is around 4.5m/s and the turbine will shut down in the event of sustained wind speeds over 16m/s. The qr5 is a 'lift-type' turbine and needs to operate at a specific tip-speed ratio to produce maximum power. The turbine is equipped with an anemometer, and if the control system determines that sufficient wind exists for operation, the turbine is actively spun-up to operating conditions at which point it enters lift-mode and starts extracting energy from the wind.

What are the noise and vibration characteristics?
quietrevolution turbines are virtually silent and vibration-free.  The noise characteristics are a substantial benefit over equivalent-rated HAWT designs.  We offer a full design package of isolation pads and mounts to meet your individual isolation requirements.
Please download our noise statement for more information.

What are the mass & loadings of the qr5?
The quietrevolution turbines are approximately half the weight of the equivalent rated horizontal axis design, and have much lighter loads. In the case of the QR5 the turbine weighs approximately 450kg – please download our mass and loads pdf for more information.  

How close can these turbines be mounted to each other?
The affect one turbine has on another will depend on the distance between them. We recommend a minimum distance of 10m between our turbines to ensure there is, for most wind directions, only a negligible impact from one with turbine to its neighbour. Closer spacing is possible but the annual yield from two turbines closer than 10m will not be 2 times the output of a single turbine.  Please contact us if you are considering spacing turbines less than 10m apart.

What safety features does the qr5 have?
The qr5 has dual, independent control systems providing redundant fail-safe operation. It has active sensors and intelligent control system to detect anomalous events. A fail-safe mechanical brake is able to quickly and safely bring the turbine to a complete stop under any conditions.

Does the qr5 have accreditation?
The turbine is designed in accordance with the appropriate European Directives for CE marking and with BS EN 61400-2 as far as possible. We are currently working with DNV for verification of aspects of the design basis specific to Vertical Axis Wind Turbines that are not fully specified in BS EN 61400-2

Is bird strike a problem?
We do not anticipate that bird strike will be an issue.

To our knowledge no quietrevolution turbine has been struck by a bird. We are confident that our turbines have not been struck as they include an impact detection switch which shuts down the turbine in the event of an impact. The turbine is not restarted without visual inspection.
There would be evidence if the turbine had been struck by a bird.

At our test site, we have witnessed flocks of birds flying directly towards the turbine, that separate and fly around either side of the rotor. When the rotor is spinning it appears as a semi-solid object and It is clear that birds can easily see the turbine and avoid it.

The risks to birds from other man made activities are far greater than that of wind turbines [especially VAWTs]. The main risks to birds are: Impacts on windows, vehicle traffic, pets etc. The order of magnitude of risk to birds from these activities is probably '000's:1 greater than wind turbines.

What’s the design life?
The qr5 has a 25 year design life.

How proven is the technology? Is it reliable?
Vertical Axis Wind Turbine technology is well established, with considerable experience in several countries, over several decades. 

The qr5 combines a number of existing proven technologies in an innovative way, including carbon fibre composites, active control systems, telemetry, and off the shelf electrical components.  Feedback from our current installations has been very good with high reliability and power generation in line with predictions.

Can the turbine be used on a “stand alone” basis, or does it have to be connected to the grid?
The qr5 turbine always needs to be connected to the three-phase mains power supply.  We do not currently offer a standalone/battery storage solution.

What is Gust Tracking?  What are the benefits of this?
Power harnessed from the wind increases as the cube of the wind speed.  This means that a high proportion of the power which can be harnessed is in the higher speed gusts of wind.  In an urban environment, with erratic wind conditions, accessing this power can make a big difference (between 20-40%) to the overall energy generated.

The qr5’s active control system uses a patented gust tracking algorithm which learns how the wind behaves in the installed location.  This information is then used to gain maximum power from the wind during gusts, optimizing turbine performance.

Is more power achieved in a ground or roof based mounting?
This depends on the wind conditions; usually the higher the turbine, the higher the average windspeed it is exposed to. But this can vary in urban environments where the wind is affected by surrounding structures.

Can quietrevolution provide wind monitoring at our proposed site?
Although this in not a standard service provided by quietrevolution, we can provide wind monitoring on request.

Is the turbine suitable for more corrosive marine environments?
The qr5 turbine is built to a marine environment specification. All paints, coatings, finishes and surfaces are engineered to withstand this environment.

What is the swept area of a qr5?  What is the size of an equivalent HAWT?
qr5 swept area is 13.6m2. The equivalent HAWT diameter is approx 4.2m diameter.

What is a capacity factor?
A capacity factor is the expected annual output at a particular site divided by the output if the turbine ran at its rated output for the whole year.
It illustrates the average level of operation over the year as a percentage of the rated power capacity. The use of capacity factors has developed from industries such as coal fired power stations that tend to run at a constant load and therefore is a good indication of the efficiency of the power station.

However it is our view that using capacity factor calculations are not really applicable to small wind turbines due to the following points:

  • If you alter the wind speed at which you rate the turbine you alter the capacity factor
  • if you reduce the rated wind speed far enough you obtain a capacity factor of over 100%
  • small wind turbines have radically different performance, power curve shapes, swept areas etc

e.g
The BWEA revised the rating wind speed of small wind turbines to 11m/s. Previously we rated our turbine at 12.5m/s.
The effect on our turbine was to reduce the rating to 4.2kW, while it had no effect on one of our competitors rating.

The reason that it effected our rating but not our competitors is because our power curve is still rising at 11m/s while the competitors flattens to horizontal at this point.
At 12.5m/s the ratings would be the same. At wind speeds higher that 12.5m/s our rating would be higher while our competitors would still be 6kW.

The competitor in question has twice the swept area ...
if the turbines had the same efficiencies over their operating range you would expect that they would produce the double the power, however at wind speeds over 12.5m/s we would produce more power than the competitor.

It is possible, even likely that a better performing turbine [annual energy output] actually has a lower capacity factor and therefore the use of capacity factors is not a good methodology for assessing the likely performance of a wind turbine.

The BWEA small wind standard [MCS 006] advises that annual energy output is a better methodology for assessment, a methodology that quietrevolution supports.

What is the capacity factor of a qr5?
To advise a capacity factor for a quietrevolution wind turbine we would need to know the Annual Mean Wind Speed (AMWS) for the rotors location and the distribution shape of the wind on the site. We would also need to have an agreement on the rated wind speed of the turbine.

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