When it comes to the safety of products and processes or the trouble-free operation of technical systems, testing and certification companies like TÜV Rheinland are the go-to address. But who actually audits the testers?

Tested quality is something you must be able to rely on

No matter whether it is safe toys or the safe operation of a power plant: When selecting a test laboratory or inspection body, it is important to know whether the service provider has the required competence. A service provider’s competence depends on a range of factors including:

  • the qualification, training and experience of its staff
  • the equipment used (calibration, accuracy, data availability)
  • the quality assurance systems in place
  • appropriate reporting and approval policies
  • adherence to current test/inspection methods and standards
  • the application of suitable sampling methods
  • market surveillance measures taken

When making a purchase, consumers want to be confident that the product of their choice meets their expectations in terms of quality and safety. To ensure this, manufacturers send products to laboratories for testing and ask an external “third party” to audit their company. In fact, such inspections and tests are confidence-building measures. The commissioned testing service providers bear a huge responsibility in this regard. Only if it is ensured that they have the necessary competence and are impartial and independent can confidence be built and maintained in the long term.

The accreditation: officially recognized competence

Accreditation is the formal recognition of the required competence. It also defines confidentiality, occupational safety and a specific code of conduct. Accreditation bodies are government appointed and thoroughly check accredited testing service providers on a regular basis. But achieving and maintaining accreditation is a big effort that not all laboratories or inspectors take. While many providers will have a valid ISO 9001 certificate for their quality management system, the requirements for laboratory accreditation (ISO 17025) or inspection body accreditation (ISO 17020) go far beyond this.


In Germany, the recognition of qualified testing service providers is a sovereign task of the federal government. Carrying out this task is the responsibility of the German Accreditation Body in Berlin (www.dakks.de).

Certificates that deserve their name

The fact is that choosing the right partner for testing and inspection minimizes the risk of product failure or non-compliance with requirements or expectations. Independent validation boosts confidence in products. Such confirmation often takes the form of a “certificate”. However, since this is not a protected term, it could be based on a single test or inspection performed by any individual or company. The “certificate” could even just reflect a manufacturer’s self-assessment. What is more, such “certifications” may not even be accepted worldwide. If a manufacturer wants to sell their product in new markets, this could then well involve extra costs.

Confidence and market acceptance can only be achieved through independent testing and inspection. A certificate that deserves its name must come from a certification body accredited to ISO 17065. Here, too, the accreditation body assesses whether a certification body follows defined procedures and is independent in making its certification decision.


Independent bodies such as TÜV Rheinland issue certificates to confirm that a specific product has been tested in conformity with a test basis (such as a standard or directive) or that a quality management system meets the requirements of the applicable ISO standard, for example. The online database www.certipedia.com provides public access to certificates for services, companies, systems and products provided by TÜV Rheinland, as well as to personnel certifications.

Accreditation and the photovoltaic industry

In photovoltaics, the main components are usually tested and certified by accredited and renowned service providers. But it is always a good idea to check a laboratory’s scope of services before asking it to conduct a test or inspection. Too often, outdated standards are used or certain testing methods are not covered by the accreditation’s scope – which means that equipment and personnel are also not subject to accreditation surveillance. When it comes to inspections, there are then no clearly defined requirements. In contrast, inspections carried out by an accredited inspection body follow defined and transparent methods and are regularly reviewed for impartiality and anti-corruption measures. To build confidence, choosing an accredited partner company that offers the desired scope of services is the way to go. And don’t shy away from asking your service provider to show you their accreditation certificate, and make sure to check whether it covers the service you require.

How to find a trusted lab

The International Laboratory Accreditation Cooperation (ILAC) is the international organization for accreditation bodies operating in accordance with ISO/IEC 17011 and involved in the accreditation of conformity assessment bodies including testing laboratories (using ISO/IEC 17025) and inspection bodies (using ISO/IEC 17020). At ilac.org, interested parties can search for accreditation bodies in the economy in which a testing service is to be provided. The accreditation bodies themselves – for example the German accreditation body DAkkS – usually offer online directories that enable a search for scopes or standards and list accredited service providers.


Dipl.-Ing. Jörg Althaus

Dipl.-Ing. Jörg Althaus

Photovoltaic Power Plant Services

Dipl.-Ing. Jörg Althaus is segment manager for photovoltaic power plant services at TÜV Rheinland. As a long-standing technical expert in the field of solar energy, he represents TÜV Rheinland in industry associations, speaks at technical forums and has contributed to many international industry standards. He has lived in Cologne for 20 years and at the same time has international responsibilities. Whenever he stays at one place for too long, he misses meeting a wide variety of cultures and people on business or personal trips. As a diver, he likes to immerse himself in the fascination of the underwater world to relax from the hustle and bustle of an increasingly fast-paced world.

More Posts


Field testing a hydrogen car for a day

So how does a hydrogen car actually drive? What should I bear in mind when refueling? Report on a hydrogen car gained during a field test.
Industrie Roboter

Industrial Applications and Safety

Robots – it is impossible to imagine production and logistics without them. Various norms and test standards ensure greater safety when using them.

Ransomware – Kidnapping in the digital age

More and more companies are becoming victims of data kidnapping. A study reveals the need for advice. How to protect against ransomware attacks.



Submit a Comment

Your email address will not be published. Required fields are marked *


No one likes popups. But you’ll like our newsletter.

Get remarkable articles on digitization, modern life, energy and technology.