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Collector Output Label

There are many energy efficiency labels around nowadays. They tell the consumers how much energy items like refrigerators, washing machines and light bulbs use, or - in the best case scenario - how little. The ErP label for "energy related products", with categories ranging from a red D to a green A+++, is the most well known.

However, even though energy labelling has now also been mandatory for heating products since 26 September 2015, those who want to know about a solar thermal system has so far had no luck. Since solar collectors do not consume any energy but solely generate heat, they are not currently labelled.

Well-known manufacturers are now implementing their own label so that consumers can be informed when choosing a product on the market that best meets their requirements for an environmentally friendly and sustainably cost-effective heating supply.

If a person chooses a solar collector, their main objective is to save primary energy and therefore costs. A good collector can cover up to 50 percent of a consumer's hot water and heating needs - and, at the same time, protect the environment. However, this is only possible if the collector actually generates high outputs.

Trust is good - tested and registered solar outputs are even better!

So that consumers can be well informed to make a decision, the heat outputs of the different collectors need to be comparable for potential buyers. Therefore, well-known system and component providers, suppliers and associations on solar heating have joined forces. Their aim is the labelling of their solar thermal collectors with a voluntary collector output label.

The voluntary collector output label for solar thermal systems allows consumers to choose, out of all the options, the collector that supplies the right output for them. The data sheet of a valid Solar Keymark certification is used as the basis. All the classifications on the collector output label have a green background, a symbol to indicate that solar collectors, which are the most environmentally friendly means to generate heat, are always ecological and efficient.

Basic registration information

The basis for registration is the DIN CERTCO Certification Scheme "Collector Output Label". The documents listed below form the basis for checking and registering. The relevant copy is only valid for dated references. For non-dated references the respective current edition of the related document including any changes is valid.

  • Certification Scheme "Collector Output Label"
  • Valid Solar KEYMARK certificate and Solar KEYMARK data sheet
  • the General Terms and Conditions of Business of DIN CERTCO
  • DIN CERTCO's corresponding fee schedule


Applicants can be both manufacturer and seller of solar panels with a valid Solar KEYMARK certificate or those who have already applied for certification with Solar KEYMARK.

The applicant must submit the following documents to DIN CERTCO:

  • Application for registration for the collector yield label in its original copy and with a legally binding signature
  • current valid Solar KEYMARK certificate for the said product
  • the completed Solar KEYMARK data sheet (ScenoCalc at least version 2.0)
  • the completed Input Excel form (template from DIN CERTCO)

After submitting an application the applicant will receive an order confirmation from DIN CERTCO with a process number and further information on the procedure and, where necessary, the application documents which are still to be submitted.

Conformity assessment

On the basis of the application documents submitted DIN CERTCO shall perform an evaluation in the form of a plausibility check, a data check, a yield check with ScenoCalc and registration of the label class.

The conformity evaluation is only performed on the basis of an absolutely certain and accurate Solar KEYMARK data sheet or an absolutely certain and accurate Excel form provided by the applicant.

The information included in the Excel form shall be checked by DIN CERTCO with the current Solar KEYMARK data sheet and then forms the basis for the registration of the collector yield label with the corresponding label class and the creation of the optional collector yield label.

If errors and/or uncertainties are identified the applicant must resubmit a corrected data sheet or Excel form.

Registration and Publication

After the submitted application documents have been successfully checked and a conformity evaluation carried out DIN CERTCO carries out registration and grants the right of use for the Collector Output Label in connection with a corresponding register number (format of register number: ELxxxx)

Furthermore a collector label (50°C and combi-label 50/75 °C) with the determined collector output for the output classes 50 °C and 75 °C is created and given to the applicant.

DIN CERTCO keeps a record of all solar panels registered with the Collector Output Label incl. their collector output and output classes, updates this record and makes it accessible to the public. All registered collectors can be retrieved on a daily basis via DIN CERTCO's homepage.

FAQ - frequently asked questions

  • What is the collector label?
    • The collector label is a voluntary product label introduced by several market players of the solar thermal market. It provides information about the performance and energy output of different solar thermal collectors in a transparent way and allows consumers to make an informed decision on the product which best meets their needs.

  • What kind of information can the consumer get from the collector label?
    • The product which best meets their needs.

      What kind of information can the consumer get from the collector label?

      The design of the label itself and the symbol for the collector makes the consumer aware of the topic: it is about solar collectors, which are considered as a basic heating technology. The icons for hot water and heating together with the temperature indicate that the solar collector is used for water and space heating. Furthermore, the scale represents the different energy output classes and the technological stages available in the market. The map of Europe shows the influence the regional location has on the output values. Furthermore, the consumer is able to proof all these information on the website of the Solar Keymark Network.

  • Which opportunities does the collector label represent?
    • The voluntary collector output label for solar thermal systems offers the consumers the possibility to choose among the different collectors according to their energy output. Its form and methodology is different to that of the already established energy efficiency label of the European Union. It has a green A-scale (A=renewable), the arrows go from the right to the left since collectors do not use primary energy, and therefore deliver heat ecologically and economically. The collector label expands the application area of the EU labelling scheme, which is currently restricted to primary energy use, by taking into consideration a sustainable, CO2-free heating supply.

      The participating companies in this voluntary labelling scheme want to strengthen the positioning of solar thermal collectors as clean, serious and advanced technologies. Solar thermal can optimize the energy balance of a house. Though, home owners can significantly save costs and even get a solar-based heat supply. The collector label could also be used as a basis for a fair grant systems based on energy output.

  • What is so special about the collector label?
    • Even when the identity of the collector label is similar to the well-known principle of the EU efficiency label, the scale is different: it shows energy output classes which relate to the annual efficiency and not energy efficiency classes which relate to energy use. The scale is green since solar thermal collectors are sustainable energy suppliers and no energy consumers. For this reason practically there are no CO2 emissions. The energy output of the collectors is taken from the Solar Keymark data sheets, which are officially issued by DIN CERTCO. The corresponding energy output potential by location is represented on the label as well. An additional advantage is that collectors can be compared to each other by the heat they generate and regardless of its construction (vacuum tubes or flat plate).

  • Why should solar thermal collectors be compared with each other by their energy output and not by their size in m²?
    • The reason is that collector modules from different manufacturers and different collector types might have the same size but can have different energy output. Subventions which are based on the size on m² of the collector field do not take into consideration how powerful the individual collectors are. Therefore, manufacturers supporting this initiative have chosen the specific energy output per gross collector area as reference to compare.

  • Why there are more energy output classes than the usual A+, A++ and A+++?
    • On the one hand, a more detailed classification allows differentiating between the different technological stages which a product could go through. On the other hand, the potential customer can quickly notice that the range of collectors available in the market is big and that it is worth it to have a closer look into the market. This differentiation makes the technological status of the individual products evident and together with the corresponding price a comparison is possible for the consumer to determine the economic benefit. The initiators of the collector label want to show with the additional classes AA and AAA the potential solar thermal has. It is expected that manufacturers will exploit this potential in the upcoming years. Reaching these classes could become a good incentive for manufacturers for product improvement. Not only consumers would profit from this, but it also contributes to achieve the „Energiewende“.

  • Why is the energy output class A- necessary?
    • The energy output class A- is necessary as a boundary line. It includes collectors, which are on the edge of current subventions scheme. It includes for instance low-cost import tube collectors with big space between the tubes. Even though they can comply with the minimum requirements to get access to subventions, which usually refer to the effective tube area and not to the relevant gross area, they get a lower ranking according to their energy output by collector module.

  • Why there are seven energy output classes?
    • The initiators want to provide a clear and meaningful classification of the products with the division into seven energy output classes. They take the criticism of consumer organizations seriously, who claim the EU efficiency label is too rough and thus revealing little. The differentiated scale prevents that higher energy output collectors are treated equal to those with low energy output. Thanks to the different energy output classes, the potential buyer quickly recognizes which product best suits his needs, because he may compare different technologies (collectors) and price ranges. In this way, the market will also be effectively protected against low-output and cheap products.

  • What do the output classes say about the technological level of the collectors?
    • Output classes Technological level

      AAA/AA In order to reach the classes AA and AAA it is necessary to have additional AA features such as double glazing, vacuum isolation or reflectors.

      A+++ Flat plate collectors of the “premium” class and vacuum tube collectors with little distance between the tubes and without reflector

      A++ Flat plate collectors of the “comfort” class and vacuum tube collectors with bigger space between the tubes

      A Simple collectors and vacuum tube collectors with considerable big space between the tubes or weak technical heat properties

      A– Very simple flat plate collectors which comply with the minimum requirements

      for getting grants, as well as vacuum tube collectors with extreme space between the tubes and non-selective flat plate collectors

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