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Introduction to Residential Wind Turbines – A Survey of Types
There are two types of small residential wind turbines; mast mounted and roof mounted.
Mast mounted wind turbines are higher rated as the masts are usually over 35’ high to catch maximum wind conditions, the roof mounted versions being rated much lower, due to their location.
This is an article on residential small wind turbines and here we will look at the different models within the two types.
We begin with an overview of the two types, then move on to compare some popular makes.
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Overview of Residential Mast and Roof Mounted Small Wind Turbines
- Mast Mounted Wind Turbines
Masts are usually around 35’ high and this enables the wind turbine to be of a higher power output of between 3 and 5kW.
They also produce electricity more reliably as at 35’ the wind is dependable and stronger.
Masts are normally installed onto prepared concrete founds, incorporating galvanized steel studs onto which the bottom flange of the mast is bolted to.
The electricity supply from the turbine runs down inside the mast then underground to the house. Here it is fed through a disconnect switch and into the main fuse box. Because of the higher power output the mast mounted wind turbines are ideal for exporting excess electricity to the grid.
- Roof-mounted Wind Turbines
Rated at 1 to 2 kW, these are not all that popular because of manufacturers claiming much higher outputs than are actually recorded. Nonetheless, there are some efficient models, which if installed in a suitable wind catchment area are capable of producing the reputed output.
They have two drawbacks; noise and vibration that in most cases is caused by proximity to the house, blade -tip speed being uncontrolled and lack of efficient anti-vibration mounts.
Remember, regardless of being mast or rooftop mounted, it is essential to check the available wind in your chosen location. The reference website below gives a good basic wind estimater, which should be used in the first instance, the manufacturer will also carry out an in-depth wind survey.
1. Which Energy Guide - Residential Wind Turbine Guide.
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Comparison of Small Residential Wind Turbines - Mast mounted
This was the content of my recent article on a Skystream Turbine, this turbine having set the quality for other manufacturers to attain.
It ticks all the boxes, with the only drawback being the price, but this is offset by its reliability due to few moving parts coupled with a consistent output. The nacelle is aesthetically designed and contains all the components including the inverter which is normally located in the house. An over-speed cut out is also incorporated in the nacelle and has a survival speed of 140mph. Anti-vibration and soundproofing is provided at the interface with the mast so transmission of sound is greatly reduced. An added bonus is the real-time readout that can be viewed through the maker’s software on a home computer.
This wind turbine is rated at 5kW and can be mounted on a 40 or 50’ mast. It has 3 blades that are manufactured from glass fiber reinforced composite and are of aerofoil shape giving maximum output with minimum noise. The yaw control, being passive, is run from the tail fin and rotor. There is no gearbox and this, coupled with a new generator design and aerodynamic shape, provides for a very quite operating turbine. Safety features include an automatic electro-brake along with a reactive pitch control. It has a low cut-in speed of 5mph, with a nominal rotor speed of 200 RPM and a survival speed of 160mph.
This turbine has 3 downwind self-regulating blades constructed from wood/epoxy which drive a low RPM permanent magnet generator produce maximum power at various wind speeds. The blade design, coupled with low RPM and direct drive means the turbine operates with low noise output; the turbine is installed on a 45’ mast. It has a cut-in speed of 6mph and survival speed of 145mph.
Below is a table showing key criteria to be used when choosing a mast mounted wind turbine. (Please click to enlarge.)
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Comparison of Small Residential Wind Turbines - Roof Mounted
- Roof Mounted Residential Wind Turbines.
This is a vertical axis wind turbine and as such can handle the wind from multi-directions and speeds.
Windterra chose VWAT’s as they operate quieter than the conventional horizontal axis turbines. The ECO 1200 is slow revving (190RPM) and more acceptable of turbulent air prevalent in the built-up areas where buildings and trees disrupt air flow, which reduces noise.
The ECO 1200 has 3 blades designed for optimum performance in all wind speeds but particularly in lower wind speed range.
The turbine has been specifically designed for rooftop mounting incorporating fully adjustable roof pitch mountings.
This is a new concept in rooftop wind turbine power generation, where the power is not produced by a normal in-line generator. Instead the power is generated on the turbines blade tips (where the maximum speed is attained).
The turbine is of circular design of 5’7" diameter, with the blades running concentrically from a bearing in the centre to the tip. The tips carrying the magnets act as the rotor, with the rim being the stator. The very low cut-in speed is 2mph and the turbine operates up to 42 mph when it shuts down. It has a “Smart box" incorporating a power controller, inverter, wind direction, and speed control.
The unit can be mounted on the rooftop or on top of a mast, but has been specifically designed to operate on a rooftop, being able to operate in turbulent winds from different directions.
Cost is $6495 (£4144).
This is a roof mounted turbine with 4 mounting kits available to ensure the turbine receives the optimum wind speeds and conditions with specifically designed mounting system with damping to reduce vibration.
It has a rated power output of 1.5kW at 450RPM and a cut-in speed of 8 mph. The rotor diameter of 6', and a dynamic brake shuts the system down in the case of over speeding.
It has a diffuser ring surrounding the blades, which reduces noise to 35dB (A), it carries a manufacturer’s warranty of 2 years, and it costs from $2400 (£1500) depending on outlet.
Below is a table showing some key criteria to use when choosing a roof mounted wind turbine, please click to enlarge.