​FAQ
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At least 20 years and more.

SAILWIND is very low maintenance. Various monitoring functions of the system ensure that in the event of a defect or a failing component, the system is automatically shut down for safety reasons. Wear and tear of parts is often indicated early by small changes, e.g. the power consumption of motors or vibrations. In this way, predictive maintenance planning - combined with the replacement of parts - can be carried out. This is called predictive maintenance. We normally expect maintenance intervals of one year. The interruptions last only last a few hours. Maintenance should be carried out by an experienced service technician or engineer who has been trained on SAILWIND.

At about 9 Bft. (storm) the system is automatically shut down with the sails fully rolled up. Only the masts with their strong guy lines are still in the wind. The SAILWIND system will also withstand short-term events of the century in gusts of up to 100 m / s. It is designed for that.

This essentially depends on the winds at the location, the feed-in tariff, the local electricity costs and how large the debt-financed portion of the budget and the borrowing rate of the capital procurement are. Wind measurements over a few months allow a good estimate of the wind speed on a long-term average. The other values are given by the local electricity supplier and the banks and are subject to changes in the market economy and should be queried at the moment. All these data influence the amortization calculation that the SAILWIND partner does with you. Under favorable conditions (30% equity ratio), your investment in a SAILWIND 12 system at a good location will pay off after 10 years. At an average wind speed of 10 m / s, around 170,000 kWh of electricity are produced. Start a wind measurement at your location and ask you bank and energy supplier for data.

In any case, wind measurements have to be made for this. The SAILWIND partner has experience in selecting good locations. If you want to start a project, a team comes and erects a wind measuring station with a data logger for a few months. These data are correlated with the simultaneous data from a nearby public wheather station. With historical data from this station over several previous years, the mean wind speed and the distribution of the wind speeds can then be predicted with quite good accuracy. With the power curve of Sailwind the average yield in kWh per year can be calculated. Even more, due to variations of the wheather from year to year also the statistical spread can be estimated.

Not only remote monitoring via the Internet is possible, but also switching on and off. Under no circumstances should you intervene in the control of SAILWIND, because it takes place fully automatically depending on the wind speed in the maximum power point. SAILWIND is self-learning and has adaptive control loops onboard. What you do yourself can only be worse!

Yes, it is designed for grid feed-in and off-grid operation. In stand-alone operation it is of course important that the generator power is drawn off. Operation with a battery storage system is ideal. In the short term, a load resistor will convert the energy into heat. If, however, less electricity is used than produced for a longer period of time, the sails are rolled and the output is reduced, possibly to a standstill.

At around 50 kW, 3-phase three-phase power of 400 V is provided, regardless of whether it is in off-grid or on-the-grid operation. The electrical installations are carried out on site, as required.

The power coefficient cp is a measure of the efficiency of a wind turbine and, according to theory, indicates how much power can be extracted from the wind by a rotor. The theoretical maximum possible at all according to Betz (1921) was calculated to be 0.59. Theoretically, only about 60% of the available wind energy can be utilized. Large wind turbines with 3 blades achieve the best performance coefficients cp of 0.45 to 0.49 in controlled operation. Small wind turbines with blades are generally less effective because the blade angle often cannot be adjusted. Blade rotors turn very quickly when they are at their maximum capacity. The tip speed is around 7 times higher than the speed of the wind. The so-called speed ratio λ is 7, which is very high. Example: The wind blows at 15 m/s. Then a bladed rotor rotates may run at a peripheral speed of 95 m/s, that is 342 km/h. Imagine the wind noise of a car at only 200 km/h! In the optimum, SAILWIND systems will have maximum speed ratio of only 1.5. So they turn at the peripheral only 50% faster than the wind. At 15 m/s according to the above example it is 22.5 m/s or a moderate 81 km/h. Wind noises will be neclectable. From literature and our first CFD calculations we know, the performance coefficients cp of SAILWIND are around 0.30. The energetic efficiency is therefore lower. The reason is the flat rotor, which in principle runs more slowly. But this disadvantage may quickly be compensated by the strength of the wind. For this you have to know that the wind speed v has a very strong influence (3rd power) of the wind speed v on the power P. P ~ cp v ^ 3 Example: If the wind speed increases by a factor of 2, this leads to 8 times the power output of the wind turbine. The mean wind speed has an enormous influence on the performance. With only 14.5% higher mean wind speed, the poorer performance coefficient of SAILWIND systems (cp = 30 % compared to cp = 45 % of a bladed rotor) can be compensated! That is very little, and extremely beneficial. SAILWINDs “only” need the right locations, which have to be carefully selected and measured beforehand. Advantage: With SAILWIND you have more options for setting up. They can be set up practically anywhere, possibly even near houses, because they are quiet and do not disturb. Some old sail windmills very often stood in the middle of the villages between houses.

A yield calculation requires knowledge of the mean wind speed at a selected location over a period of one year. With a little experience, good locations can be predicted. But, measurements at this location need to be conducted at the correct height. One speaks of the hub height of the horizontal wind rotor. In the case of SAILWINDs on old mill towers, this hight ranges between 7 and 8 m. Should a modern SAILWIND system on a steel mast come into question, greater hub heights could also be aimed for, provided the location allows it. Electronic wind measuring devices with data loggers can be loaned to measure selected locations over several months. From these measurements, mean annual wind speeds are extrapolated based on a comparison of existing local weather stations in the vicinity. This enables a very reliable forecast of the average energy yield in kWh per year of a SAILWIND system.

In the past, sailing windmills were often built at exposed wind locations. These are special locations where the shape and topography of the terrain lead to a significant increase in the local wind speed. This is generated by the effect of a congestion at an obstacle such as a mountain or a slope. A valley or incision between two mountains, a so-called yoke, is particularly effective. A kind of nozzle is created. This nozzle effect effect can be enormous and lead to a wind speed that is more than twice as high as that of the wind on a plain or at undisturbed height. The special thing about these locations is that the height above the ground does not have much influence on the nozzle effect. On the contrary, the nozzle effect tends to decrease with altitude! Therefore, lower hub hights of SAILWINDs are not really a disadvantage if you find the right location with expertise and intuition (and of course wind measurements), i.e. preferably on slopes or knolls or in aisles between elevations.

We expect SAILWIND to be very quiet due to the lower tip speeds of the rotor. Much quieter than other wind turbines with blade rotors at the same distance! So there should be no problems sleeping in or near the mill. However, should SAILWIND be too noisy, e.g. with strong winds and gusts at night, the rotor speed can be limited even down to zero. That is a matter of the settings in the programming, which you can do yourself.

With its flat wind rotor, SAILWIND belongs to the group of slow runners. Birds and bats can perceive the rotating rotor and avoid it. Nature protection is important to us! SAILWINDs can therefore also be built in bird sanctuaries without any problems. In contrast to large wind turbines, which should be banned at these places. We aim to get a bat protection certificate for SAILWIND.

SAILWIND is a small wind turbine with a low hub height. Sail windmills are historical cultural assets in all Mediterranean countries, Portugal and southern France. The mills are part of the landscape and fit in perfectly. So new SAILWIND systems will not be a problem at all, even if they have a modern appearance with a reduced nacelle and are mounted on short steel masts with a hub height of max. 10 m. SAILWIND will therefore have a high level of acceptance in these regions. In Central Europe, SAILWIND will probably only become established once the unique advantages have become known. After all, other types of mills were common here, not those with sails. Because new locations for large wind turbines are becoming increasingly scarce, and large wind turbines are also becoming less and less accepted by us, decentralized, independent energy supply with small wind turbines (home wind turbines) and photovoltaics (PV) is becoming more and more important. Incidentally, studies have shown that buildings below 30 m in hight are hardly noticeable in views from 100 m distance.

Of course, but that would only make sense if you set up a hybrid system with PV and battery storage on the spot. But even then it is important that energy is used as regularly as possible. It would be very uneconomical if the battery storage is full, no one comes to charge, and wind and sun are available at the same time.

In principle yes for logos, lettering and color combinations. Lasers would offer excellent animation for advertising. However: one-colored (white) sails are definitely the most beautiful. And advertising will certainly not be permitted for historical sail windmills. But for the test machine SAILWIND 4 we could definitely reserve the sail for sponsors.

Basically yes, but old foundations should be checked by specialists (civil engineers) and new foundations should definitely be carried out according to the engineering plans of your SAILWIND partner.

Every SAILWIND is equipped with remote data transmission. Operating data of every system are saved on web servers so that they can be called up anywhere in the world.

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