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FAQ - Buying Considerations

No. Efficiency is a measure of how much of the kinetic energy in the wind is converted to electrical energy. It is unavoidable in low efficiency generators that large portions of energy are lost in the conversion process. This is not the case with Kestrel generators. Even when a wind turbine is generating power at its maximum capacity, the electrical energy produced is only a fraction of the potential energy in the wind. Efficiency is a matter of engineering (generator design) and the limits of physics. Capacity factor is a measure of a wind turbine's actual output, which varies with the wind speed, over a period of time.

No, turbines have a bad reputation for being noisy and invasive but Kestrel's wind technology has eliminated mechanical noise. Although there is a subtle hum that is caused by the wind passing through the blades, this is almost undetectable in high winds as the noise of the wind masks the sound of the blades. The aerodynamic noise has, however, been minimised by Kestrel's blade and upwind design. The certification of small wind turbines clearly restricts noise emissions and Kestrel complies with these guidelines in order to guarantee maximum unobtrusiveness.

The Kestrel factory situated on Eveready Road in Port Elizabeth, known as 'The Windy City', is committed to certifying its turbines and are extensively testing each unit to achieve the highest quality and reliability. All units tested in the field have performed well for years with minimal maintenance. The maintenance manual issued by Kestrel requires that the bearings are changed every couple of years or so, depending on your wind area.?

?The high technology of a wind turbine is in just a few manufactured components such as the blades. A wind turbine can actually be much simpler than a diesel engine. It also requires much less attention and maintenance. The turbines, for example, have only three moving parts and do not need any routine maintenance. They can operate for five years or more, without any attention. Small wind turbines are mainly used for rural energy in developing countries. Rural electrification of houses, villages, farms and small industries can often be done less expensively and more quickly with renewable energy, such as wind power than by extending the national grid.

Grant assistance depends on the renewable energy policies in your home country.

Some do but due to Kestrel's advanced design Kestrel's turbines do not stop in high winds. The pitch control reduces the surface area of the blade that is exposed to the wind and stops it from over producing energy. As the speed of the blades pick up, they twist round to change the angle of the face of the blade. The twisting, known as pitching, alters the angle of the blades that stalls the speed of the rotor so you turbine will never over speed. This means that even in the strongest winds the turbines will continue to produce the maximum power without stopping.

Once at optimal wind speed the turbine produces its rated output, in order to maintain this rate of generation in wind speeds exceeding optimal wind speed, Kestrel uses a pitch control system. The e220, e300i and e380i are equipped with pitch controls, whilst the e150 self-regulates. The pitch control pitches the blades in order to adjust the speed of the rotor with respect to the prevailing wind speed, this is achieved by angling the face of the blade, thereby optimising output from the turbine.

Your investment is recouped through the utility costs that you save by maintaining your own source of electricity. In comparison to purchasing utility power your Kestrel's electricity does not harm the environment, increases the value of your home and is totally customisable to your needs.?

Modern wind turbines come in many sizes and are divided into size classes. The large wind turbines range in diameter from 30 to 65 metres on towers of up to 80 metres in height. Kestrel manufactures small wind turbines which range in diameter from 1.5 to 3.8 metres on towers of up to 18 metres in height.

A residential wind turbine is part of a system that supplies electricity for your home or chosen application. The turbine collects kinetic energy by facing into the wind which passes through the turbine system which converts it to usable electricity. The collection process begins with the rotor which is rotated by a number of blades, which in turn rotates the shaft of the generator. In most cases, residential turbines supply energy to the home along with the normal utility company supply, as your power requirement may exceed the output of the turbine system. In high wind areas less supplementary supply is necessary from the local grid. In some cases and countries, any excess electricity from the turbine may be sold to the national grid.

Like any high-tech machine with moving parts, including cars, turbines must be maintained and serviced at regular intervals. If the turbine is properll=y serviced and moving parts are replaced when necessary your Kestrel wind turbine can generate for up to 20 years.

Interestingly, large wind farms equal the energy pay back period of coal and nuclear power stations which is six to eight months. The Kestrel factory does utilise its test farm to supplement its electricity supply, which contributes to minimising the energy pay back period. The estimated energy pay back period is ................?

There are several factors that must be considered when you are calculating your Kestrel turbine's pay back period. Firstly, your local wind resource will tell you how much energy you will generate and receive. Secondly, electricity costs which include what you paid for the turbine, what you pay for electricity from the traditional grid, what you get paid for the electricity your turbine produces and whether you qualify for a grant. This will enable you to calculate monetary savings and income less costs over time that gives you your pay back period.

The cost of solar panels range from between R300 to R9000. Even though the R300 one is cheaper, it ends up being more expensive because it has a life span of about two to four months before it is sun baked and useless. The R9000 panel however, is a Siemens product that comes with a 20 year guarantee (August 2002)

Turbines generally do not use power, however the energy cost of generating with a turbine is usually referred to as line loss. By moving generated energy through the system, a small fraction of that energy is lost to friction. This line loss is minimised in Kestrel's as the generator is one of the most efficient.

Every Kestrel wind turbine has a cut-in wind speed and a rated wind speed, some turbines have a cut-out wind speed but this is not the case with a Kestrel turbine. Its rated wind speed is the speed at which it produces its rated output. At the cut-in wind speed, the blades start to turn. Kestrel turbines are producing energy when the blades start turning at between two and three metres per second. A cut-out wind speed shuts down a turbine. However, pitch control feathers the Kestrel blades to let the wind flow past them, slowing the rotations to optimal output. A cut-out speed usually means that there is a sizeable delay in generation as turbines with cut-out speeds only restart at a cut-back-in speed.

?Assuming that the system would power sixteen 11 Watt fluorescent light bulbs the costs for construction and installation would be as follows, (This would be the equivalent of providing eight dwellings with 11 Watt fluorescent light bulbs/ two bedroom dwellings Description of costs Cost in Rands 1 x 75 Watt Solar Panel R 4987 1 x Wind Turbine (400 Watt) R 5700 16 x Light bulb fittings R 1600 4 x Step up transformer R 280 Insulated copper wiring assuming the dimensions of an average 2 roomed house) R 770 16 x Light bulbs R 640 16 x Light switches R 128 Installation cost (performed by a qualified electrician according to SABS standards) R 1800 TOTAL R 15 905 Total (that each house would pay (eight houses) R 1988 Further research and development would diminish costs Classes of wind power Wind Power Class* Wind Power Density (W/m2) speed (km/h) 1 100 15.84 2 150 18.36 3 200 20.16 4 250 21.6 5 300 23.04 6 400 25.2 7 1000 33.84

In Europe and the United Kingdom wind energy is ranked as one of the most popular energy technologies. In some developing countries, like South Africa wind energy is a relatively new energy technology. It must not be forgotten that wind has been used to pump water for many decades and turbines are just an advancement of the potential energy in the wind that can be harnessed to benefit you and your business. Kestrel's turbines are Proudly South African as they are manufactured in Port Elizabeth.

Generally, modern wind turbines are very reliable. Kestrel's turbines are manufactured using durable and high quality materials to strict manufacturing standards which increases their reliability and lifespan.

Grid tie systems and putting surplus onto your local grid is dependant on the country in which you live, the amount of electricity you supply and the local supply value of electricity. It is important to realise that a grid tie inverter is crucial to grid tie systems as 'raw' power cannot be put onto the grid.

There are many different applications for the high efficiency generator, your imagination is the limit.

?We would say, without a doubt, it is suitable - but, then again, we are the proud manufacturers. To offer an objective opinion is impossible, so here is the Energy Saving Trust's point of view: Individual turbines vary in size and power output from a few hundred watts to two or three megawatts (as a guide, a typical domestic system would be 1 - 6 kilowatts). Uses range from very small turbines supplying energy for battery charging systems (e.g. on boats or in homes), to turbines on wind farms supplying electricity to the grid. You should consider the following issues if you're thinking about small scale wind. An accredited installer will be able to provide more detailed advice. Wind speed increases with height so it's best to have the turbine high on a mast or tower. Generally speaking the ideal site is a smooth top hill with a flat, clear exposure, free from excessive turbulence and obstructions such as large trees, houses or other buildings. Small scale wind power is particularly suitable for remote off grid locations where conventional methods of supply are expensive or impractical. Please note that the electricity generated at any one time by a wind turbine is highly dependent on the speed and direction of the wind. The windspeed itself is dependent on a number of factors, such as location within the UK, height of the turbine above ground level and nearby obstructions. Ideally, you should undertake a professional assessment of the local windspeed for a full year at the exact location where you plan to install a turbine before proceeding. In practice, this may be difficult, expensive and time consuming to undertake. Therefore we recommend that, if you are considering a domestic building mounted installation and electricity generation is your main motivation, then you only consider a wind turbine under the following circumstances: The local annual average windspeed is 6 m/s or more. An approximate figure for your location can be checked on the BERR website There are no significant nearby obstacles such as buildings, trees or hills that are likely to reduce the windspeed or increase turbulence If you are in any doubt, please consult a suitably qualified professional. Planning issues such as visual impact, noise and conservation issues also have to be considered. System installation normally requires permission from the local authority, so it's important to always check with your local authority about planning issues before you have a system installed.

Depending on your own power requirements and wind area, in most cases your utility bill can be drastically reduced by using the energy generated by your Kestrel turbine.

Please send an electronic enquiry or contact us directly for a referral.

The more of these conditions apply to you in the United States, the shorter your payback period will be: You pay more than 10 (US) cents/kWh for electricity, and your electric bill averages at least $150 per month. Your electric utility offers net metering. You are located in a class 2 or higher wind site (click hereto see a U.S. wind class map). Your state has a substantial wind power rebate program that will help offset the system?s cost. The more of these conditions apply to you as a South African, the shorter your payback period will be: You do not have access to electricity from the National Grid. Load shedding is paralysing your home life or business. Your electricity bill averages at leastZAR615 per month. Irrigation costs are marginalising your profit margins. There are appliances in your community that are costly to the collective. Wind systems will be more and more cost-effective as energy prices increase. The decreasing price of wind will be further assisted if the South African government participates in the global trend of wind subsidies and grants.

Since 1990 world wind energy capacity has more than doubled every three years which has dramatically reduced the cost of generating electricity with wind turbines. Wind energy costs are competitive with new coal and new nuclear capacity, which include environmental costs. Also unlike coal, nuclear and gas as power sources, the wind is free and widely available as a fuel source. Therefore, once your Kestrel is in place, there are no fuel or waste related costs.

?The sun is an abundant energy source. This system does not make any pollution while converting sun radiation into electricity that we can use. The sun is an eco-friendly power source (clean and green energy source). The panels are reliable and need minimal maintenance, the sun is also reliable because it provides the panels with a constant energy supply which does not change direction, unlike the wind turbines. Solar panels have a long life ( provided one purchases a good quality one). Reduces greenhouse gasses. No noise pollution. Fixed cost of electricity (cents per kilowatt-hour) for the life of the system. Solar panels after installation are very easy to operate and maintain. The electrical energy stored in the batteries can be used on cloudy days or after sunset.

Easy and quick installation. Wind systems come in small and all sizes and have a shorter construction lead time than extending the utility lines (""grid"") in remote areas. Low maintenance. Wind turbines can operate for extended periods without attention; with only a few moving parts (the e150 - 600W has no moving parts), these systems have very low maintenance requirements, typically needing to be inspected only every two years during their 20- to 40-year design life. Further, with training and spare parts, local users can support the wind turbine equipment that they are using. Generation of local employment. Small wind turbines are not difficult to manufacture. In this respect, local manufacturing, under license or through a joint venture is often a suitable option for developing countries since they would benefit from reduced foreign exchange requirements, better support capabilities, local economic development and, usually, lower production costs. This is why Kestrel is Proudly South Africa! Economical. Wind systems replace existing household expenditures for kerosene, candles and dry-cell batteries and are the best option from the user? s point of view since operational costs are not a burden i.e no fuel needs and readily available and affordable spare parts as well as wind, which is free Mitigation of climate change Other Advantages and Disadvantages can be found by clicking this link to Energy Efficiency and Renewable Energy Information Centre

Safety. Modern wind turbines are very safe and can operate for many years without any problems. However, it is critical that safety precautions be taken when installing and operating a small wind turbine. One issue to consider in northern climates is ice accumulation on the blades. Hydrogen venting from batteries is another potential issue. Climbing of towers by the owner or maintenance persons is a potential liability. Special safety precautions are required if children have access to the system. Extreme weather. In some parts of the country, the environment is very hard on equipment and can cause operational and durability problems for the wind energy system and batteries. Special turbine components, lubricants, and maintenance schedules may be required to keep the turbine in optimal generating condition. Corrosion of system parts at locations close to the ocean can also be a problem. Neighbours. The proximity of a wind turbine to a neighbour's property should be discussed with the neighbour before proceeding with a wind energy system purchase. As a rule of thumb, a turbine should be sited at least one or two times the tower height from any property lines. Aesthetics. The visibility of a particular wind system will depend on many factors, including tower height, proximity to neighbors and roadways, local terrain, and tree coverage. A wind turbine can affect your view or that of your neighbours, and it might block or change an historic landscape. In most areas of Canada, wind turbines are also an uncommon sight so it is natural to expect some local reservations about their introduction. Objections are more likely to occur in populated and tourist areas. Opposition is least likely to surface in rural settings. Noise. The noise level of a turbine depends on several factors, including local wind characteristics (i.e. gusting and rapid changes in direction), terrain (flat v. hilly) and the design of the turbine itself. Most modern turbines are not disruptive as long as they are properly sited. For more details, see our Social, Environmental, and Other Considerations page. Zoning and Other Legal Issues. Local municipal offices should have information on restrictions with respect to acceptable noise levels and permissible tower height. Local wildlife. Small wind turbines can pose a danger to birds in certain conditions. However, as shown in the graph at right ( Source: Erickson,, 2002. ""Summary of Anthropogenic Causes of Bird Mortality""),wind turbines are far less of a danger to birds than buildings or household cats. To minimize any potential problems, avoid siting a wind energy system on a migration route or where many birds nest and feed. The system should also be designed to reduce perching and nesting opportunities. This is typically not a problem with smaller systems. See our Social, Environmental, and Other Considerations page for more on wildlife issues. Electromagnetic interference (EMI). Small wind turbines, such as those sized for residential and farm use, have not been found to create interference with television signals. In fact, small wind systems are commonly used today to power remote telecommunication stations for both military and commercial uses. Most wind turbines use blades made of wood, fiberglass or composite materials that don't cause reception problems. Many years ago, a few wind turbines equipped with long, metallic blades did cause some localized problems, but they are no longer commonly used.

The blades turn the generator shaft that is housed in the nacelle. Except in the e150 which has a static hub, the pitch control sustains optimal rotations per minute of the shaft and is housed in the nosecone. The tail ensures that the turbine's blades remain pointed at the oncoming winds. The unit is usually mounted on a tower.?

The blades are made of glass-fibre reinforced with poly??? The generator, pitch control and towers are made of galvanised steel.

Other than the obvious (a wind turbine), your system costs depend on your requirements. For a battery-charging system, you will need a tower, a charge controller and a set of batteries.

Some local authorities have outlined decommissioning processes in their planning permission statements. If your local authority does not have this kind of documentation it is recommended that all visible traces be removed from the site when decommissioning your turbine. In all respects the environment should be accommodated for.

Kestrel systems are designed to ensure a constant flow of power, which is the reason that the system includes batteries on the system. In the cases where there is no wind for a period, power is drawn from the batteries which were charged in high wind periods. If you choose not to have batteries on the system and excess energy is fed into the local grid, in low wind periods the local grid supplies energy back to you. The amount of storage capacity you will need is dependant on your power requirement or other forms of generation are required.

The capacity factor is calculated by taking the actual output over a period of time as a proportion of a wind turbine's maximum capacity. For example, if e300i (1kW) turbine generates power over one year at an average rate of 0.8 kW, its capacity factor is 80% for that year.

An inverter is a product that is used on the Kestrel turbine electricity generating system. Inverters are used to convert the dc electricity generated by the turbine to ac electricity that is used by appliances in your home. Inverters also manage the flow of electricity through the system, especially on grid tie systems. On such systems any excess energy produced is directed onto the grid by the inverter?

There is no cut-out wind speed. The e160i, e230i, e300i, e400n are designed to produce full power in any wind above 12m/s. The e230i, e300i and e400n models are fitted with a patented pitch control. Blade pitch control is the system which monitors and adjusts the inclination angle of the blades and thus controls the rotation speed of the blades. At lower wind speeds, the pitching system leads to an acceleration of the hub rotation speed, while at higher speeds, blade pitch control reduces the wind load on the blades and structure of the turbine.

Small turbines are designed for individuals and businesses to directly customise their renewable energy consumption. Kestrel's can directly supply you home, back up your grid power, power a tool, area without grid or a building. The variation in output is balanced by battery storage or supplemented by the grid. Whereas large wind turbines supply the grid itself.

Because of the many application possibilities and types of systems, we cannot release prices. So, you can either contact a distributor using the Distributor Locatororsend an enquiry by clicking HERE. Please remember to include the following details: Your location. So that we can tell you the average wind speed in your area. Your requirements. You can calculate your own requirement using this Power Calculatoror you can simply send a list of appliances. The intended application. Simply, as a back-up power source, to decrease your grid power use, to pump water, to use as an educational tool etc etc. This way we can attend to your need and make accurate recommendations as the system type and size.

We cannot release prices because of the many application possibilities and types of systems. For system sizing and pricing, please contact the Kestrel distributor in your area or contact our Head Office by clicking here. Please remember to include the following details: Your location (GPS coordinates) Your requirement ? you can calculate your own monthly energy requirement by using the energy calculator Intended application ? grid connected, off grid or water pumping?

Output from your turbine varies with the wind, literally. Depending on your area, and the site that you install your turbine. But even in moderate wind areas it is possible to maximise your energy generation potential by increasing the height of your tower as well as ensuring that there is less air turbulence which affects your turbines performance. Kestrel is able to advise you on optimal site position.

Exactly what does the warranty cover? Is the turbine covered for at least five years? What are the exclusions or restrictions? Read them carefully. What is the top wind speed, after which warranty coverage is excluded? (The warranty should be good for winds of at least 100 mph.) Is the warranty transferable to the next homeowner? If you do not understand any part of the warranty, don?t be afraid to ask questions.

This answer depends on the amount of power you use on a day-to-day basis as well as the wind area in which you live, which highlights the renewable resource available to you. In a good wind area, you can power your home with a e380i or in combination with solar energy in other areas.

?A small wind system can be used on-grid (for a cottage, home, farm, or business) or off-grid (for a boat, RV, cottage, home, farm, business, remote community, or remote station): For on-grid, small wind can help supplement your grid electricity and reduce your dependency on the local electrical utility. For off-grid, small wind can help provide electricity to remote locations for both seasonal or year-round use. For isolated grids (not connected to the national electrical grid), small wind can help reduce the use of diesel generators, thereby saving fuel costs and reducing pollution. For Water Pumping, small wind can help move water from a borehole, river or dam to a reservoir. This method is much more efficient and cost effective than the traditional windmill.?

Anyone who is keen to generate renewable energy that is readily available, fully customiseable and not harmful to the environment. Turbines also make ideal back up power systems to alleviate the inconvenience of load-shedding or black outs.

All Kestrel's turbines are manufactured to the latest IEC International Wind Turbine standards. Turbines which are designed under these standards will be low impact and follow the guidelines on colour and aesthetics (colour is white non-reflective). The blue is just the non-invasive Kestrel touch. Wind turbines should be silent if used in domestic situations and our silent ones have no noise and can be placed outside your bedroom window if required.

The tail on a Kestrel turbine makes sure that your turbine faces into the wind in order for the wind to turn the rotor. This is how it generates electricity for you. Every component of your turbine is practical and contributes to the maximum energy extraction from the wind.

Old fashion designs that have become icons of the country side enjoy a measure of nostalgia. However, it is a little known fact that they are very inefficient in comparison to modern developments. Every aspect of Kestrel's turbines is designed to increase generation efficiency and energy yield, so in comparison with their forefathers Kestrel's yield cheaper electricity and lower maintenance costs. Every effort has been made to keep Kestrel's aesthetically pleasing.

The more blades a turbine has the lower the maximum speed of the turbine. Generally, turbines that generate electricity need a high rotations per minute (rpm) rate and so have fewer blades. Also the amount of output is dependant on speed of the rotor. For instance, the e150 (rated output of 600W) has three more blades than the e220 (rated output of 800W). Having more blades means that the e150 can self-regulate without pitch control as it operates at lower speeds. Although two bladed machines are lighter than the Kestrel turbines, they are noisier and do not turn with a fluid motion.?

A battery-charging system will continue as normal as it has no interaction with the local grid, however grid inter-tie systems will not be able to interface with the local grid during a power cut. In some cases an inverter will control the grid and turbine interfacing, if not you must disconnect your turbine.?