Electrical output from wind generators
All manufacturers indicate that their product delivers x number of watts at a given wind speed, but the numbers are unfortunately so fluffy that it can be difficult to use them much.
The electrical output from a wind turbine (as shown here at the left, on our own Rutland 1200, as an example) is from manufacturer to manufacturer, measured in various ways. Rutland give up their numbers by these conditions:
“The Wind generator must be mounted on a 10 meter mast in our factory and it is not optimal location for output maximization, as there is a lot of turbulence, but turbulence is part of reality and therefore we test such. It is important to have a robust Wind generator and no burden on a Wind generator more than turbulence! We test over a long time and repeatedly, to achieve statistical reliability. The turbines will have factory on one side and open fields on the other ”
It is one of the most realistic testing we have seen in Energig. Many Wind generator manufacturers does not indicate the conditions under which the tests is performed.
A test in a wind tunnel can not really be used for anything, in fact, when it comes to output data from a tunnel virtually never exist in reality.
But when Rutland states their numbers under these conditions as they do, then we can count on them in reality? No, we can not, for if your wind turbine sits on a truck, a boat or on an cabin, meaning there is turbulence from the mount, sheltered from the houses / trees around the truck / boat and tomorrow the truck / boat is located in a new spot. This all means that your Wind generator will deliver less power than what you see in Rutlands measurement. Which Rutland fully recognize and even notes.
This is not something new and we have handled it on sailing boats for decades, which is sometimes on the high seas and other times is well protected in sealed ports and the rule of thumb is that you should divide the given watt figure by 2. sometime you will have more energy, at other times less, and you will almost never achieve the output specified by the manufacturer, in fact, the reality can not be recreated in a test setup. It is not easy being a producer 🙂
Test and turbulence
The same is true if one takes a test of wind turbines on the web where you put x number of competing Wind generators up on a mast each, side by side. Partly because the turbines are in the exactly the same conditions (although it looks like it) as there will be a difference as soon as you move the turbines 2-3 meters apart and although if we forget for a moment the differences, the test is only accurate if it reflects the exact environment in which you want to mount your Wind generator.
Eg. if a test with Wind generators mounted on a mast in a garden, cannot be compared to your needs to install a Wind generator on your boat or a caravan. The turbulence will be different and the shape of the nacel, wings and tail fin, will make a Wind generator able to do very well on a test, but not be the best choice for your application. And you can not know for sure before making a purchase. Sorry, but that’s the truth, unfortunately.
Energigs Rutland Wind generator are optimized as land wind generators and/or marine wind generators. It is not only relative to output that they are optimized.
Marine wind generators is better to handle turbulence than the land wind generator. Because waves always makes turbulence and when a boat is moving, it moves the wind pressure on the wind generator, which is also a turbulence (it also provides another load on bearings. Gyro effect etc., but that’s not what we’re talking about now: )).
This short article has been on the electrical output and that is often the first our customers looks at, but in our opinion it’s not the most important thing to think about when buying a wind charger.