How do you fancy building your own small wind turbine?

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Posted Sep 24 2015 by Robin Duval of V3 Power
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The UK has one of the world’s best wind resources, and exploiting it with small wind turbines is something that, in the right context, can be a very efficient source of power. Wind turbines, however, come with a fairly long list of handicaps when comparing them to other renewable technologies such as solar. One of these is planning and the sizeable ‘anti-wind’ lobby in the UK, something that, often due to ignorance, lumps small and big wind in together. Another is siting – due to small wind turbines operating at a much lower altitude than their larger cousins they are much more affected by obstacles such as trees and buildings, meaning that where they are placed has a huge effect on their efficiency. And finally, due to their having moving parts and being placed in very harsh conditions they are prone to break and need regular maintenance. However, even with all these handicaps, for those willing to undertake the adventure, small wind can prove highly rewarding.

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Given the fluctuating nature of the UK’s renewable energy market and the handicaps of small wind mentioned above, many small wind manufacturers and installers struggle to stay afloat, leaving customers with turbines that they are unable to have serviced or repaired. This also means that many turbines on the market have very limited field testing and their long-term reliability is unproven which makes investing in them a bit of a gamble. Although there are good machines available on the market one increasingly attractive option, especially with the seeming demise of the feed-in-tariff, is to build your own.

The undisputed king of the self-built small wind turbine is the design by Hugh Piggott. The primary reason for this is that Hugh Piggott has been developing this design over more than three decades and using it to power the off-grid community where he lives on the west coast of Scotland. This means that the reliability and efficiency of the design can be demonstrated in a challenging real-world situation, not merely by some extrapolated calculations. The design has been adopted by many organisations around the world that want to take advantage of being able to build their own wind turbines as well as research groups wanting to test its efficiency and effectiveness as a means of rural electrification. The results are very encouraging, showing that a well-built Hugh Piggott machine performs comparably to commercial machines but with a much smaller capital outlay.

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The Hugh Piggott Design

Hugh Piggott publishes his design in his Wind Turbine Recipe Book, which is a construction manual for the six different sizes of his turbine. The smallest has a diameter of 1.2m with a power rating of 200W, whilst the largest has a diameter of 4.2m and a power rating of 1kW. Exactly how much power any small wind turbine will produce is a difficult question to answer, but one that is often asked. The problem is that unlike solar radiation, the wind resource of a given location is difficult to predict. In addition, due to the nature of wind, a relatively small increase in average wind speed can result in a dramatic increase in generated power. Thus, the best, albeit slightly flippant answer when asked the question ‘What can that turbine power?’ is ‘What is your average wind speed?’. For example the 4.2m machine generates 67kWh a month at an average windspeed of 3 meters per second but will generate 286kWh if the average windspeed is 5m/s. But as mentioned above, this is a problem that all small wind suffers from – and the fact remains that given a good site it can be the cheapest form of renewable energy available.

The Hugh Piggott turbine has been designed with ease of manufacture in mind. It utilises relatively easily available materials and simple methods for its construction. This means that it can be built almost anywhere – from community workshops in Peru to a garage in the UK. This brings with it various benefits: firstly, it is often the cheapest option; secondly, local manufacture brings down the embodied energy of the final system; thirdly, it means that replacement parts can be easily manufactured when needed; and finally, it can be hugely empowering for the owner of the turbine, be that a community or individual, to have full control over their system and be able to deal with any eventualities themselves.

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The turbine is made up of three sections – a metal mounting, an alternator made up of magnets and hand-wound copper coils cast in resin, and three hand-carved wooden blades. Everything is made from scratch except the bearing, which can either be a new trailer bearing or a salvaged bearing from a car or van. The entire turbine can be constructed entirely with hand tools, except for the welding. The alternator uses neodymium magnets, which are exceptionally strong and help to keep the overall size of the generator small. However, they are both expensive and have a relatively high embodied energy. The coils are hand-wound from easily available winding wire which means that when constructing the alternator you can optimise it to work with a battery bank of a given voltage or to be grid tied. Wooden blades mean that both manufacture and replacement is relatively easy. When maintained, wood is exceptionally durable and strong and when sourced responsibly is a fantastic sustainable resource. In addition to constructing the generator you also need a tower to put it on and an electrical system to connect it up to. It is important to include these costs when assessing the viability of a small wind system.

The typical use of a Piggott turbine is in an off-grid situation where it is used to charge a battery bank. It is particularly useful when there is already a solar PV system in place. Adding a wind turbine is often the best way to expand an existent off-grid system as you are able to do this without expanding the battery bank which is a significant cost in the system. By diversifying your generation capability to be able to generate at night and on cloudy days you are also able to minimise the risk of running out of power due to weather conditions, especially in winter.

Piggott turbines can also be grid-tied. Although effective on a technological level this is often financially imprudent in the UK at the moment due to feed-in-tariffs. Due to the self-built nature of the turbine it is unable to receive the feed-in-tariff and thus is unable to compete on a level playing field with other turbines. Nevertheless, it can still make sense to grid-tie a Hugh Piggott where your base-load electrical consumption is relatively high due to the bills savings that you will accrue. As the feed-in-tariff reduces and electricity prices increase, grid-tied Piggott turbines will become increasingly financially attractive.

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Next Steps

For those interested in Hugh Piggott turbines there are a few things to consider. The first is planning. Although there is permitted development for small wind turbines, the Hugh Piggott turbines don’t comply as they are not MCS (the government’s renewable energy certification scheme) accredited and have a larger swept area than is permitted. However, the insistence on accreditation for planning is based largely on noise generation and there have been successful planning applications that use noise data for similar commercial machines to satisfy the local authorities. There have also been cases of successful retrospective planning being granted.

The second consideration is the site of the turbine. As mentioned above, the site has a huge impact on how well the turbine performs. The first thing is to check the general wind resource of your area. You can do this using online resources (http://www.rensmart.com/Weather/BERR). Then you need to check if you have a site that is not too obscured by objects such as buildings and trees that will block the wind.

If you are interested in getting a Hugh Piggott turbine you can simply order a manual – http://www.scoraigwind.com/axialplans/index.htm#BUY and build one. Or you can get an older version (but still a goodie) from Lowimpact here – https://www.lowimpact.org/build-wind-turbine/. Alternatively we at V3 Power run courses (http://v3power.co.uk/courses/) teaching people how to build Hugh Piggott wind turbines and can help in acquiring materials, giving advice or manufacturing parts or entire turbines/systems if needed. We have been building Piggott turbines for almost 10 years and are always keen to try to facilitate self-build wind turbine projects getting off the ground!

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References/further reading:

Recent V3 Power Piggott installation – http://v3power.co.uk/install-at-nant-y-cwm-farm/

V3 Power – http://v3power.co.uk/

Hugh Piggot Blog – http://scoraigwind.co.uk/

V3’s Upcoming Courses: 3-4th October. Organiclea, Chingford, London. £225 / 10-11th October. V3 HQ, Nottingham. £225

To book a place and for more information visit: http://v3power.co.uk/public-courses/

  • Get hands-on experience and learn transferable skills in welding, wood carving, and working with magnets & resin
  • Learn how to build and install a Hugh Piggott wind turbine from scratch using basic materials
  • Experienced tutors who have been running courses building Piggott turbines since 2007
  • A practical fun course for all experience levels

On the course we collectively build a 1.8m diameter Hugh Piggott wind turbine. All the participants spend time working on each of the three main parts of the build (wood, metal, and electronics) rotating through the different bases on the first day. On the second day we then come together as a group to assemble the machine.

Technical information