The path to certification
In 1996 the International Electrotechnical Commission (IEC) published the first edition of the IEC 61400-2 standard Safety of small wind turbines and this was updated in 2006, as the second edition – Design requirements for small wind turbines.
Other related documents include 61400-11 Acoustic noise measurement and the 61400-12 Power performance measurements. These are the three international standards that verify that a small wind turbine is well designed, safe, and is performing properly.
Nevertheless in the last 15 years almost no turbines have been certified to these standards and industry stalwart Mike Bergey says, “there is a strong correlation between certification and bankruptcy in the small wind turbine industry”.
The 61400-11 (acoustic) and 61400-12 (power) standards are large wind turbine standards with an annex that deals with simplifications for small wind turbine testing. In contrast the 61400-2 (small wind) standard is specific to small wind turbines, and so it is worth understanding the intent behind it:
In its 1996 first edition the IEC assumed small wind turbines were up to about 40m2 in swept area (about 10kW) and it included some simplified design equations so that designers did not need to generate the complex aero-elastic mathematical models that large wind turbine designers use. In large wind turbines once the design models are created a prototype turbine is built and heavily instrumented, and the actual load data measured and compared with predictions.
This measurement of loads is time consuming and expensive, and the subsequent analysis is a specialised and expensive task. Instead the small wind turbine community substituted a lengthy duration test as an alternative way of ensuring a turbine would remain safe in service (if the manufacturer did not wish to use measurement of loads as a route to certification).
The 2006 second edition had access to measured load data for a range of turbines up to 200m2 and so they were able to write a fuller range of simplified design equations up to this size.
However the way in which the support structures were dealt with was ambiguous and many felt that this meant testing a turbine of every variant of its support structure. Clearly this is an expensive process, as turbines of about 5–6kW will often have twenty or so different support structure options. For example some clients will need guyed towers, others monopole towers, others freestanding lattice towers, others will need designs suited to heavy ice loading and others will need designs suited to active seismic locations.
There was further uncertainty about exactly what should be measured and reported, when conducting power and acoustic tests.
| "There is a strong correlation between certification and bankruptcy in the small wind turbine industry." |
| - Mike Bergey |
All these uncertainties drove up the cost of testing and certification. It is widely believed that the certification for the 2.4kW Skystream by Germanischer Lloyd cost US$250,000, which was largely funded by the US government. Many smaller turbine manufacturers would find such a cost prohibitive.
Just as the IEC 61400-2 second edition was being published in 2006, the American Wind Energy Association (AWEA) started work on a stripped down version of the IEC standards – incorporating references to -2, -11, and -12, but further defining what testing was needed and excluding exhaustive testing of all support structures. It was intended that compliance with the AWEA safety & performance standard would be certified by the Small Wind Certification Council (SWCC), which was set up in 2009. And it is hoped that the final AWEA standard will be issued in early 2010.
Also during 2010 the SWCC – in partnership with NREL – will develop regional test centres around the USA and Canada. The direct subsidy of the SWCC and the regional test centres by the US authorities addresses another of the industry's concerns; that it is the certification bodies and test laboratories which are expensive, rather than the standards themselves.
What about the reputation of the small wind industry?
In late 2006 the British Wind Energy Association was addressing another of small wind's major issues: how best to handle the new entrants into the small wind turbine industry who were promoting the widespread installation of wind turbines on buildings and making extremely optimistic performance predictions.
Naturally well-established manufacturers were not happy with the new breed, as they saw the newcomers trading on a reputation built up by their hard work. Equally the UK government was concerned because of the potential for grants being given in support of products that were not performing, or worse, that were actually unsafe.
The British manufacturers were perplexed at the prospect of being forced out of business by the cost of full IEC certification and concerned at the anti-competitive situation that might be created if they wrote a UK-specific standard.
For this reason they chose to adopt the then draft AWEA standard, stripped out all references to the SWCC, and replaced them with references to EN 17025 test laboratories and EN 45011 certification bodies. They called this the BWEA safety & performance standard, and routed the certification element through the Microgeneration Certification Scheme (MCS) – which the British government was establishing for all microgeneration technologies. This MCS certification scheme and the BWEA standard which it draws upon were reviewed by the European Commission and deemed not to be anticompetitive, because they create international competition in the testing and certification market for any accredited EN 17025 laboratory or EN 45011 certification body.
The BWEA standard was first issued in 2008 and a second edition issued in 2009. There was considerable transatlantic dialogue necessary in keeping the UK and USA markets interoperable, and therefore to date the two standards are almost identical.
| "It is widely believed that the certification for the 2.4 kW Skystream by Germanischer Lloyd cost US$250,000, which was largely funded by the US Government." |
The second edition of the BWEA standard dealt with the issue of better adapting the IEC 61400-11 (acoustic) standard to the realities of small wind turbine testing, and is the version that turbines are now being certified to:
- In October 2009 the Proven 15 kW model completed certification through TUV-NEL using testing conducted by an organisationally-separate part of TUV-NEL, and this is the first turbine to complete the BWEA certification process;
- The second turbine seems likely to be the much smaller Ampair 600 or the larger Gaia, and in this case the testing has largely been conducted by NaREC or NWTC respectively, whilst certification is being conducted by TUV-NEL.
These two turbines will have therefore demonstrated two distinct pathways through the testing and certification process.
The only thing that remains is for TUV-NEL to complete the EN 45011 accreditation process and receive a licence from the MCS scheme administrator Gemserv, and the manufacturers can then receive full MCS product certification.
And a third pathway is for the manufacturer to conduct the testing under the close supervision of the certification body, and it is believed that Iskra/Evance may be going this route with BRE-C as their certification body. Other certification bodies are believed to be close to announcing that they are open for business. Commercially a number of testing and certification bodies are now issuing quotations ranging from £50k to £100k for testing and certification, which is a vast improvement on the $250k cost for SWWP's Skystream.
In addition, increasing familiarity with the processes, research on improvement to these processes, investment in testing equipment, and competitive processes will continue to drive down costs even more.
About the author
David Sharman is managing director of the UK wind turbine manufacturer Ampair.
He serves on a number of small wind turbine committees including the international IEC and IEA committees; the USA NEC committee; and the UK committees of the MCS and the BWEA.
He is a systems engineer with a BEng (Hons) from RNEC Manadon and an MSc from MIT. Prior to Ampair he was an officer in the Royal Navy, and an operations and project manager in Shell.
He has lived and worked in many countries around the world including several years in Latin America. This article expresses his personal views.
