Tail fin leading edge
Rust along leading edge of tail fin.
Deterioration of rubber mount and washer stack behind.

Washers Rusty display screws on inverter.
Blade saddle crack
Cracks between blade and saddle, paint missing where nose cone touched blade.

(Click any image to enlarge) Opens in new tab

Part 3: Summary - Good, Bad & Scandalous

Bergey Turbine – the GOOD:

  1. Very simple design, with little to go wrong, wear out or break.
  2. Extremely strong blades. The 'pultruding' process means there is a very high quantity of orientated glass fibre which makes the blades exceptionally robust.

Bergey Turbine – the BAD:

  1. The blades are fixed profile along their whole length, which is less than optimal regarding energy capture and noise.
  2. Old technology inverter makes an annoying whistle while operating.
  3. Poor design / manufacture leaves a number of components not fitting or deteriorating in just a few months, for example:
    • tail-fin cut from pre-galvanised sheet but has no post-guillotine treatment so cut edges rust,
    • nose cone (spinner) doesn't fit properly so packed out with a stack of washers,
    • nose cone anti-vibration mounts made from UV susceptible material and cracked badly.
    • inverter display screws have no corrosion protection so go rusty.

    • None of the above is particularly difficult to put right, but it demonstrates a poor design attitude or bad quality control.

  4. Cracks between blade and mounting saddle. In itself this is not of structural significance BUT it allows water/ice into the blade root which could not be inspected. Any problem at the blade root would be masked - a worry considering how often the turbine 'over-speeds'.

Bergey Turbine – the SCANDALOUS:

The UK Government issued a certificate under its MCS programme and promoted and encouraged people to install this wind turbine. The certificate includes a noise specification, but despite being installed correctly (and checked by NAPIT) at certain speeds the Bergey doesn't meet its specification by a huge margin! Further, just above the test range the turbine is deliberately allowed to over-speed and make even more noise.
Over-speed overlay on power curve
Published Bergey power curve, with overlay of the over-speed problem.

I believe these faults make this turbine unusable near habitation and brings the whole Government certification scheme into disrepute.
  1. Cogging from the alternator induced resonance resulting in a 'fog horn' noise, 'warbles' and acoustic disturbance significantly outside its MCS noise specification. Listen to resonance recordings from Part 2:
  2. Gross over-speed. Once the inverter reaches maximum power the turbine stays into the wind with no mechanical regulation. The turbine then escapes to a very high speed with associated massive noise output. The noise has been compared to a helicopter or turbo-prop aircraft. This is a deliberate Bergey design decision; I assumes it is in order to maximise yield, which could otherwise make the Bergey appear uneconomic.
  3. The turbine is not permitted to be left in a 'braked' condition, so can not be legitimately stopped after installation.

Hutchinson's Tower – the GOOD:

  1. Light weight with relatively small foundation block means minimal environmental impact.
  2. Easy to build and fairly low cost.

Hutchinson's Tower – the BAD:

  1. Structural resonance when used with Bergey turbine.
  2. Excessive deflection (too flexible) during gusty wind conditions. However my own (very crude) test using a Telehandler to support the tower suggests that it does meet the deflection/load requirements specified by Bergey in their 'Manufacturer Tower Design Requirements' document. This suggests that the problem is more likely to be excess load being applied by the turbine.
  3. Weld distortion of flanges leaves a question as to the exact tension in the fixing bolts.

Screen dump from MCS web-site
Extract from MCS web-site.

Micro-generation Certification Scheme (MCS)

In the next part of this write-up I attempt to go through the correct procedure and raise a complaint via MCS. After a year this eventually results in a meeting with representatives from MCS, BRE Global (the certification company) and DECC ('Department of Energy and Climate Change'). In summary: they appear desperate to avoid recognising this as a scheme problem.

The screen dump opposite is how MCS markets itself, be warned it is just propaganda.