The D400 Wind Generator

  Designed to be attached to your house, outbuilding or boat.

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Given average wind speeds at the site of around 12 mph, one D400 / StealthGen could realistically provide 15 - 20% of the average home’s annual electricity requirement.

The D400 / Stealthgen is a 400 WATT direct-drive wind generator, designed for a variety of marine, rooftop or terrestrial applications. It is exceptionally quiet and vibration-free in operation, qualities that are of paramount importance for any wind generator operating in close proximity to people. The D400 is available in white, or low visibility black as the Stealthgen.

Conventional wisdom has largely precluded the mounting of wind generators on buildings due to the unacceptable noise and vibration associated with such installations. The D400 Stealthgen overcomes these problems.

It is small and light enough to be easily attached to most building structures.  

The D400 features a powerful 3-phase alternator, and computer-designed rotor blades optimised for low speed, user-friendly operation.

This innovative machine is extremely efficient in low wind speeds, yet is capable of sustained high power outputs of up to 500 watts in higher winds.


Grid connect the Stealthgen's output is connected to your ring main via a G83 inverter which produces 240 volts AC @ 50Hz synchronized to the grid. When the Stealthgen's power is not required in the house, the surplus flows back out to the local grid. You will need an export electricity meter and tariff agreement with the power supplier if the value of your exported energy is to be credited. Note  that grid-tied inverters are designed to be switched off in the event of power failure.

For single turbine grid tie installations you can either use a  72V turbine together with an SMA WB700 inverter or a 48V turbine with a Mastervolt Windmaster 500 inverter (the inverter efficiency level of the system is 75% in real world conditions)

The turbine control box / G83 interface has several functions - a) it contains a voltage limiting circuit which prevents over-voltage conditions at the inverter input. This can occur during the three minute mandatory grid monitoring period following a grid failure and re-connection (G83 requirement). b) it contains a DC isolator switch (required under G83). This is of a 'no volts' type which trips out when the grid fails. The system cannot be reset until grid power is restored. This switch also operates a relay which brakes the turbine when grid power is lost. c) it contains a brake switch which allows the turbine to be stopped without taking the inverter off line.

NOTE : the conventional Landis & Gyre type meters will not accurately record AC outputs. They typically under-read by a factor of 3 to 4. High sample rate meters are required.

A typical equipment list for the grid tie D400 turbine is:

D400 for grid connection  (72V or 48V) =  £1020.00 ex VAT = £1224.00 inc VAT

Turbine control unit for grid connection (G83 Interface)  = £580.00 inc VAT.

Wall Bracket = £275.00 inc VAT.

Windmaster 500 grid tie inverter option is  £565.00 inc VAT.

Windy Boy inverter option : please ask for details.

Single MC4 Plug for the Windmaster 500 inverter  = £6.20 each inc VAT.

Single MC4 Socket for the Windmaster 500 inverter  = £6.00 each inc VAT.

6mm Radox double insulated DC cable  = £4.39/metre inc VAT.

Battery inverter AC systems - the Stealthgen's output is used to charge a battery bank. The battery bank has an inverter which produces 240 volts AC. A battery-based system can produce power during periods of grid failure and will function as part of a stand-alone supply to an off-grid building. We generally recommend that the D400 is installed together with a regulator to prevent battery damage through overcharging.

Stealthgen/D400 is £1041.67 ex VAT = £1250.00 inc VAT

Regulator is either the 6TB12 or the 6TB24.

6TB12 is £181.92 ex VAT = £218.30 inc VAT for the 12v version

6TB24 is £203.49 ex VAT = £244.19 inc VAT for the 24v version

* Using a Tristar 60A regulator you can run up to 250 watts of Solar panels as well as the D400.

** A Dumpload may also be required.

Stop Switch 12V or 24V  is £19.32 ex VAT = £23.18 inc VAT

Spare set of D400 blades is £ 169.70 inc VAT

Shipping cost extra - based on customer delivery address and equipment list (delivery weight). Standard delivery cost in the UK is £ 25.00 inc VAT

Battery-charging installations do not need a bypass switch, but customers may want to install a stop switch to slow and stop the blades prior to securing.


Hybrid micro wind/ photovoltaic systems - the Stealthgen can be used to supplement the power from other devices such as diesel generators and PV arrays.

DC direct supply to fluorescent lighting

DC supply to water heating

Battery charging (transport)

Hybrid ground source heat pump systems

D400 wins Practical Boat Owner magazine Nov 2005 test for BEST OUTPUT.

Nine of the most popular wind generators used by yachtsmen were tested over the summer. The testers were keen to assess output at 9 knots wind speed, which is the average summer wind speed on the UK’s south coast. And in such gentle breezes, the D400 proved to be more than twice as productive as the next best machine, even though two of the other units were larger. The output recorded was 3.8 amps. In fact, the D400 continued to outshine its competitors up to wind speeds of nearly 20 knots, when the Air X joined in. The D400 was also judged to be “exceptionally quiet.



Specifically designed for installation
on boats, and on or near buildings

• Almost silent in operation
• Smooth running with optional integral
anti-vibration mount
• Unparalleled low wind speed performance
• Low tip speed ratio, 1.1 metre diameter rotor
• Advanced variable camber airfoil blades
• Robustly engineered for long trouble-free service
• Highly efficient, low-speed, 3-phase axial field
permanent magnet alternator
• Excellent heat dissipation with heavy duty
encapsulated windings for sustained
high output operation
• Aesthetically attractive design
• Corrosion-resistant materials used throughout
Available in 12, 24, 48 and 72 volt DC
• Turning circle – 585 mm
• Mounting tower 2’’ O/D tubing
Weight 15 kilograms

 The length of the tower liner (insert into the pole) is 80mm.

Output Guide:

10 knots wind speed produces   40 watts
15 knots wind speed produces 120 watts
20 knots wind speed produces 190 watts
25 knots wind speed produces 280 watts
32 knots wind speed produces 400 watts

NOTE: These figures are representative of performance at sea level when operating in an open, turbulence-free site.

D400 turbines can be installed singly or in multiples.

Each micro wind installation will produce up to 10 kW hours per day under 'ideal' conditions, depending on the prevailing wind speed.

A realistic annual yield at a typical urban site would be around 660 Kw hours which equates to a daily average of 1.8 kW hours per day (20% of average UK household electricity consumption)

Electricity bills are based on an annual consumption of 3,300 kWh/year or 9 Kwh /day.   (Source : Government News Network, Nov 2005)

Consumption varies according to whether the household has two working people (around 4200 Kwh /yr), one single person (around 3000 Kwh/yr) or a family with children at school (around 5400 Kwh/yr)




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