Solarmaterialien: Rückwandlaminate von Krempel
Solar Materials

Backsheet laminates for solar modules

Insulation and protection for photovoltaic modules over several decades.

We are a pioneer in the dynamic photovoltaic market and a leading manufacturer of backsheet laminates for solar modules. With their unique multi-layered structure consisting of fluoropolymer films and polyester films, the Krempel backsheet laminates stand out thanks to their excellent mechanical, electrical and chemical properties.

Krempel offers modified products for various different applications and technologies:

  • Crystalline modules with fluoropolymers
  • Crystalline modules, fluoropolymer-free
  • Thin-film modules
  • Reverse-side contacting

The main function of the backsheet laminates is to provide the solar modules with electrical insulation, but they also protect against harmful environmental influences such as UV radiation, moisture, extreme temperatures, microparticles such as grains of sand and harmful gases such as ammonia, which helps to prevent costly failures.

Backsheet laminates are a decisive factor in ensuring unimpaired functioning and the guaranteed service life of 25 years.

Krempel backsheet laminates are produced on highly specialised, latest-generation laminating machines using adhesive systems developed by us. They are available as rolled materials or pre-cut parts, and either stamped or unstamped. The narrow rolls for covering cross-connections completes the product range for solar technology applications. In addition to our premium, no-compromise variants, we also offer cost-optimised materials.

Only the best of everything

The optimal choice of material

It is extremely important to us that only the best raw materials are used to produce our backsheet laminates, which helps to guarantee the proven Krempel quality over several decades.

We draw on our over 30 years of practical experience to select the optimal materials for our customers based on their particular applications. We work in close collaboration with our customers to optimise not only the efficiency of their solar modules but also their production processes.

Distinguishing features of the Krempel backsheet laminates:

Rückwandlaminate für Solarmodule
  • High yield due to optimal reflection
  • Compatibility with standard polymer encapsulants
  • Hydrolysis stability due to extremely high-quality core films
  • Cell resistance thanks to UV-stabilised primer
  • Extremely low permeability (WVTR)
  • Extremely high weather resistance
  • High transparency for BIPV
  • Compliant with IEC61730:2016 for system voltages of > 1000 V or > 1500 V
  • Partial-discharge-certified to IEC
  • Independent certification by UL File QIHE2.E312459
  • Over 30 years of field experience in all of the world’s climate regions

Service life put to the test

Krempel backsheets undergo a comprehensive series of tests as well as accelerated age testing, where we go beyond the required minimum values of the relevant IEC specifications.

Our comprehensive standard, type approval and special tests are carried out on the backsheet as a standalone component or on complete dummy modules.

The following factors are tested in detail:

  • Moisture/thermal resistance
  • UV stability
  • Adhesion/peel strength
  • DTI (Distance Through Insulation)
  • Partial discharge
  • CTI (Comparative Tracking Index)
  • RTI (Relative Thermal Index)
  • FSI (Flame Spread Index)
  • WVTR (Water Vapour Transmission Rate)
  • PCT (Pressure Cooker Test)
  • Ammonia resistance
  • Chemical resistance
  • Temperature cycle
  • Humidity/freezing
  • Abrasion
  • Weather resistance
  • Tensile strength
  • Elongation
  • Dielectric strength

Our portfolio

Fluoropolymer-based backsheet laminates for crystalline modules

The classic laminates in our AKASOL® series use fluoropolymer film as the cell layer and the outer layer and have proven their worth over more than 30 years of use all around the world. They are available either with TEDLAR®-PVF films or KYNAR®-PVDF films. The range is also supplemented by cost-optimised versions. These versions still use a fluoropolymer film as the outer layer, but the side of the sheet closest to the cell is designed as a primer layer consisting of high-quality UV absorbers. The polyester films are combined with adhesion promoter in the optimal proportion to their thickness.

The Yellowing Index proves that fluoropolymer films are UV resistant on a long-term basis, and have the previously underestimated benefit of significantly inhibiting flammability and flame spread. For the electrically insulating inner layer, we use modified, dimensionally stable polyester films for all of our backsheet laminates in the AKASOL® series. This allows us to achieve the required partial discharge resistance for any system voltages required for the solar modules up to 1500 Volt. For buildings designed with integrated PV modules (BIPV), we provide backsheets that can be harmoniously incorporated into the architecture thanks to their approximating colours or transparent design.

Layer construction of a fluoropolymer-based backsheet laminate for crystalline modules

Schichtaufbau eines Backsheets für kristalline Module
1 2 3 4 5

Outer layer/external protection

PVF/PVDF

External protection with TEDLAR®-PVF or KYNAR®-PVDF films in different thicknesses.

Inner layer

PET

Hydrolysis-stable core films for reliability, durability and good mechanical and insulating properties

Cell layer

PVF / PVDF

Cell protection either in the form of durable UV-stabilised primer or TEDLAR®-PVF or KYNAR®-PVDF films

Adhesive

Adhesive systems specially developed by Krempel

Adhesive

Adhesive systems specially developed by Krempel

Fluoropolymer-free backsheet laminates for crystalline modules (PET backsheets)

Safety and reliability are the decisive factors when selecting materials for solar modules, but there is also a demand for more cost-effective alternatives on the solar market. We have found the perfect balance between our dedication to quality and the market requirements, and have developed the cost-effective AKALIGHT ECS® backsheet variants. These combine our tried-and-tested cell layers with a special UV-stable polyester film that is designed to be reliable when used in the outer layer in line with the discerning Krempel standards.

Layer construction of a fluoropolymer-free backsheet laminate for crystalline modules

Schichtaufbau eines Backsheets für kristalline Module
1 2 3 4 5

Outer layer/protective layer

PET

UV-stable and hydrolysis-stable polyester film for reliable external protection

Inner layer

PET

Hydrolysis-stable core films for reliability, durability and good mechanical and insulating properties

Cell layer

Primer layer

Cell protection thanks to durable UV-stabilised primer

Adhesive

Adhesive systems specially developed by Krempel

Adhesive

Adhesive systems specially developed by Krempel

Thin-film modules

Thin-film solar modules need to be protected against the ingress of moisture. This is ensured by an additional barrier layer in the form of an aluminium inner layer. Thin-film modules have a cost-optimised design based on glass-film technology. They are resistant to water vapour ingress in accordance with ISO 15106-3.

Either a fluoropolymer film or a special UV-stable polyester film can be selected as the outer layer.

Our backsheets for thin-film modules are based on our tried-and-tested backsheets for classic solar modules.

Layer construction of a thin-film module

 Schichtaufbau eines Backsheets für Dünnschichtmodule
1 2 3 4 5 6 7

Outer layer/protective layer

PET

UV-stable and hydrolysis-stable polyester film for reliable external protection

Adhesive

Adhesive systems specially developed by Krempel

Barrier layer

Aluminium film

Adhesive

Adhesive systems specially developed by Krempel

Core layer

Modified, hydrolysis-stable polyester film specially developed for solar applications

 

Adhesive

Adhesive systems specially developed by Krempel

Cell layer

Primer layer

Cell protection thanks to durable UV-stabilised primer

Reverse-side contacting

In our backsheets for reverse-side contacting, the outer layer consists of a fluoropolymer film. A copper film is used to ensure optimal electrical contact with the side of the sheet closest to the cell. This innovative technology increases the efficiency of PV modules.

Accessories

Insert strips in a thin design for optical coverage and additional insulation.

Repair strips for covering minor damage. Cold processing is carried out on the finished module. Once applied to the solar module, it will be resistant to heat and moisture.

Jochen Enderle, Key Account Manager, Global Sales Mobility
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Jochen Enderle
Key Account Manager
Global Sales Mobility

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