Questions we get asked
Production figures, dimensions, grid connection, permits and what happens in a storm, answered with the numbers from the published product sheets and honest about what is not published yet.
Production figures, dimensions, grid connection, permits, and what happens in a storm — answered with the numbers from our own product sheets, and honest about what we haven't published yet.
Production
How much electricity does a WM 25 kW wind turbine produce in a year?
At a mean wind speed of 7,0 m/s at 50 m height the yearly production is 40 600 kWh. That is a reference case value, not an estimate for a specific site. The same reference case at other wind speeds, all at 50 m height: 33 600 kWh at 6,5 m/s, 47 600 kWh at 7,5 m/s and 54 600 kWh at 8,0 m/s. Mean wind speed is by far the biggest factor. Across that range, 1,5 m/s changes yearly production by more than 60 %. What that speed is at your site depends on the region and on the terrain, land cover, buildings and tree canopy around the wind turbine. So rather than reading a single number off this page, enter your own coordinates in the Wind App and get an estimate for your site.
How much electricity does a WM 1000 W wind turbine produce in a year?
At a mean wind speed of 7,0 m/s at 50 m height the yearly production is 2 590 kWh. That is a reference case value, not an estimate for a specific site. The same reference case at other wind speeds, all at 50 m height: 1 295 kWh at 5,5 m/s, 1 672 kWh at 6,0 m/s, 2 102 kWh at 6,5 m/s, 3 105 kWh at 7,5 m/s and 3 644 kWh at 8,0 m/s. Mean wind speed is by far the biggest factor. Across that range, 2,5 m/s makes yearly production almost three times higher. What that speed is at your site depends on the region and on the terrain, land cover, buildings and tree canopy around the wind turbine. So rather than reading a single number off this page, enter your own coordinates in the Wind App and get an estimate for your site.
How much electricity does a WM 100 W wind turbine produce in a year?
150 kWh at a mean wind speed of 7,0 m/s at 50 m height. That is a published reference figure, not an estimate for a specific site. At 50 m height, the same reference case runs from 70 kWh at 5,5 m/s to 220 kWh at 8,0 m/s. Mean wind speed is by far the biggest factor here too, with production more than tripling across that range. What that speed is at your site depends on the region and on the terrain, land cover, buildings and tree canopy around the wind turbine.
Do the wind turbines work in low wind speed?
Yes, all our wind turbines operate from 3,5 to 22 m/s. Below 3,5 m/s wind speed the rotor does not produce, and above 22 m/s it is stopped. Inside that range, the mean wind speed at the site drives almost everything. For the WM 25 kW we publish 33 600 kWh a year at a mean of 6,5 m/s at 50 m height and 54 600 kWh a year at a mean of 8,0 m/s at 50 m height. Those are reference case values, not estimates for a specific site. What that mean speed is at your site depends on the region, the terrain, land cover, buildings and tree canopy around the wind turbine. Enter your own coordinates in the Wind App to get an estimate that takes all of that into account, together with historical wind data for your location.
How much would a wind turbine produce on my farm?
The production varies greatly with wind availability and the surroundings. Without a location, any production figure would be a guess. Our published numbers all come from reference cases at a stated mean wind speed at 50 m height. That speed varies a lot between sites, and production follows it: the WM 25 kW does 33 600 kWh a year at 6,5 m/s and 54 600 kWh at 8,0 m/s, both measured at 50 m height. Drop a pin on your land in the Wind App and it estimates hub-height wind speed and annual production from historical wind data, terrain, land cover, buildings and tree canopy. You can also simulate your consumption with different profiles and see how it lines up with production across the year. Then get in touch and we will go through the wind data, terrain, placement constraints and the consumption side with you.
How accurate is the Wind App estimate?
The Wind App is an early-stage planning tool and does not replace a technical site assessment. It combines historical wind data with local terrain, land cover, buildings and tree canopy to estimate hub-height wind speed and annual production at the pin you drop, and it covers locations in Europe. It runs in the browser, is free and needs no account. The app also covers the consumption side, so you get an estimate of yearly savings, self-sufficiency and what a battery would change. After that we refine the estimate with internal tools and pinpoint the best placement on the property.
Size and site
How tall are the wind turbines?
The WM 25 kW is 21,5 m tall to the top of the wings on a 17,5 m tower, with a 10 m rotor diameter and 85 m² of swept area. The WM 1000 W is 9,5 m tall on an 8,4 m tower, with a 2,5 m rotor and 5 m² of swept area. The WM 100 W is 4,2 m tall on a 3 m tower, with a 0,8 m rotor and 1 m² of swept area.
How much ground area does the foundation cover, and does it need a concrete foundation?
None of our wind turbines need a concrete foundation. All three models are anchored with steel soil screws. The WM 25 kW has a foundation 6,0 m across and a tower base 3,3 m wide. The WM 1000 W has a foundation diameter 2,0 m across, and the WM 100 W 1,0 m. The screws are installed with a small jig in a few hours and are load-tested on site as they go, with no curing time. The soil screws are simple to uninstall and can in most cases be reused.
How long does installation take?
Expect 1–2 weeks on site for the WM 25 kW before it is producing. The glulam tower arrives in sections for transport, is assembled horizontally on the ground and then raised. The soil-screw foundation goes in within a few hours and needs no curing time, so the schedule never waits on concrete.
Can I put a wind turbine on my roof?
We have tested the WM 100 W for roof mounting and brackets are available. However, roof mounting is only suitable in a limited number of cases. For good performance, the building should either be free-standing or significantly taller than nearby buildings. The turbine location on the roof must also be chosen carefully, and the roof structure must be able to withstand the loads and vibrations generated by the turbine during high winds. In our experience, many rooftops have too little wind or are not designed to withstand these loads, making roof mounting unsuitable in many situations.
Neighbours and permits
How loud is the wind turbine?
We have not published a measured sound power level, so we will not quote one here. The entire wing sits at the same distance from the axis, so it moves at a uniform, relatively low speed, 30 to 70 rpm on the WM 25 kW. Conventional horizontal-axis wind turbines have long wings whose tips move much faster than the rest of the wing. Slower wings make less noise, and the 3D-printed winglets we put on our wings help reduce it further. The sound it does make drops off faster with distance than a horizontal-axis wind turbine of similar output. For a planning application we produce sound and shadow projections for your specific site.
Low wing speed, quieter and easier on wildlife.
Do I need a building permit?
For a WM 25 kW, expect to have to apply for a building permit. Thresholds vary from country to country, but a wind turbine 21,5 m tall with a 10 m rotor will cross them in most places, so check the rules with your local authority. We can help you with the technical documentation for the authority, including sound and shadow projections for your location, and we go through the placement constraints with you before that.
Do I need permission for a WM 25 kW in Denmark?
Yes. The WM 25 kW falls within the “husstandsvindmølle” category, which covers a single wind turbine with a rotor area of a maximum of 200 m², a total height of a maximum of 25 m and a maximum output of 25 kW. The WM 25 kW meets all three at 85 m², 21,5 m and 25 kW. You need a simple building permit from your municipality. It will be difficult to get a building permit for any wind turbine installation within an urban zone (byzone). Getting a landzonetilladelse is a simpler process; contact your local municipality for more information. Installation of a wind turbine in Denmark larger than 5 m² swept area requires the wind turbine to be IEC certified. The certification of the WM 25 kW is underway.
Do I need permission for a WM 25 kW in Sweden?
Yes. A building permit is required for wind turbines above 20 m in height or with a rotor diameter above 3 m, and the WM 25 kW is both, at 21,5 m tall with a 10 m rotor.
What about birds and bats?
The VAWT wing rotor spins at a slower speed than a conventional wind turbine. Research suggests that the fact that the wings are always visible in the horizontal plane makes it easier for birds and bats to detect and avoid the wings, which reduces collision risk. Reducing the impact on local biodiversity is a consideration throughout the design process.
Operation and durability
Do vertical-axis wind turbine wings suffer from fatigue?
Fatigue is a real design challenge for a lift-based VAWT. Each wing moves with and against the wind once per rotation, so the load swings cyclically every revolution. Early Darrieus designs from the 70s and 80s struggled with this, working without the materials and simulation tools available today, and it is part of why the concept lost ground back then. That has changed. We extrude the wings in a modern high-strength aluminium alloy and reinforce them internally with steel at the strut connections, where the stress is highest. Structural simulation (FEA) lets us run the full load spectrum before anything is built, and we keep all operational loads below fatigue stress with a safety factor. To validate our simulation models, we have tested wing stress with strain gauges on the wings of the WM 10 kW wind turbine prototype and found close agreement between measured bending stress and the simulations.
What maintenance does our wind turbine need?
A yearly inspection on the WM 25 kW and the WM 1000 W. The design keeps service simple. There is no gearbox and no yaw mechanism, so there are fewer moving parts and no gear losses. On the WM 25 kW the generator sits at the base of the tower, which makes service and inspection easier. Regulation is stall-controlled, meaning excess power is shed aerodynamically, so there is no active pitch mechanism to maintain. In Denmark the yearly inspection of the WM 25 kW is a legal requirement and has to be carried out by a certified company. We handle service and maintenance on it for the first five years. The WM 1000 W has no such requirement, but we recommend a yearly check of the load-bearing parts. The WM 100 W needs no yearly inspection.
What happens in a storm?
The WM 25 kW has three independent braking systems: the generator itself, a pair of hydraulic disc brakes at the top of the driveshaft that stop the rotor in a controlled way across the full operating range, and a pair of spring-applied parking disc brakes at the base. Both brake pairs engage automatically if the control system loses connection, and they work without electrical power. We rate the WM 25 kW and WM 1000 W to a maximum survival wind speed of 42 m/s, and the WM 100 W to 35 m/s. Operation stops at wind speeds above 22 m/s, and the rotor is locked in place.
What is the lifetime of our wind turbines?
The WM 25 kW is designed to IEC 61400-2 class IV and a minimum lifetime of 20 years. The WM 1000 W is designed to IEC 61400-2 class IV and a minimum lifetime of 10 years.
What are the wind turbines made of, and can they be recycled?
On the WM 25 kW and WM 1000 W, extruded aluminium wings and a pressure-treated glulam tower on a galvanised steel foundation with soil screws. No glass fibre and no concrete. The wings are extruded from a low-CO2 aluminium alloy by ProfilGruppen in Sweden and the pressure-treated GL30 pine glulam comes from Moelven. Unlike glass fibre composite wings, aluminium wings can be fully recycled at end of life.
Choosing a wind turbine
Which model fits my site?
The WM 25 kW covers multiple households, farms, production sites or businesses, and is meant for open landscapes with wind: fields, coastlines and rural areas. The WM 1000 W is sized for off-grid houses and for residential or commercial buildings at windy locations. The WM 100 W is for small-scale demands such as off-grid sensors, signs and charging points, and it tolerates turbulent placement, including rooftops. The Wind App gives a site estimate for the WM 25 kW and the WM 1000 W.
How does it connect to the grid?
The WM 25 kW is connected to the grid through a certified regenerative power drive with a three-phase 400 V output, and an optional 25 kWh battery pack can stabilise the connection. The WM 1000 W outputs 48 V DC with battery-charging management and requires an optional 220 V CE-approved inverter to connect to the grid. The WM 100 W is not offered with a grid connection: it outputs 24 V DC under electrical MPPT control, with an optional 500 or 1000 Wh battery. All three log to Energy Machines Cloud, which you reach from a browser or a phone app.
Can I buy one today?
The WM 25 kW is in operation: our first one is installed and grid-connected at Halmstad in Sweden and is in its testing, optimisation and certification phase. The WM 100 W is in operation too, running at sites in Denmark and Sweden. The WM 1000 W is in development. We publish its specifications to explain the design and gauge interest, and they may change before production starts. There is a waitlist if you want to hear when that changes. Tell us about your site and we will say where each model stands.
Still have a question?
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