ReNew PV - Coating to increase the service life of PV modules with damaged backsheets

Extending the lifetime of photovoltaic (PV) modules is one of the most pressing challenges of our time. As PV becomes more and more established as a renewable source of electricity, it is crucial that PV modules can generate electricity reliably over a long lifetime and are sustainable from an energy, environmental and investment perspective. One approach to this is the introduction of new PV technologies with increased performance and service life. A second approach is to significantly extend the lifetime of existing PV modules by reusing, repairing or refurbishing them. While recycling is the standard strategy for end-of-life PV modules in Europe, strategies and methods for reuse and repair are still emerging. However, the repair of early damage in particular, but also of faults after a long period of operation, is often economically advantageous. Damage to the backsheet, which is one of the most common causes of module failure alongside glass breakage and cell degradation, already showed a high repair potential in the predecessor project "PVRe2".
The main objective of the project is to develop an environmentally friendly coating solution for the repair of backsheets (to extend the service life) of PV modules.

Solutions for the following 3 scenarios will be developed:

• Scenario 1: (Preventive) restoration of the insulation resistance of PV modules
• Scenario 2: Repair of defective backsheets (cracks)
• Scenario 3: Repair of transportation and assembly rejects (mechanical damage to the backsheets)

Another goal is to research and develop business models for an efficient repair infrastructure, i.e. an optimized application methodology and logistics for the coating in accordance with the three scenarios mentioned above.
Approach 1: Local application to mounted PV modules in the field ("spray can")
Approach 2: Centralized, automated coating of dismantled PV modules ("2nd Life PV") in the field (mobile container with coating system) or at an external facility.

The procedure for achieving the objectives is (1) to survey the repair requirements of the PV installations and identify the production and transportation damage (modules with damaged backsheets of real aged modules and scrap modules), as well as (2) the analytical methodology for determining the material type and composition of the backsheets. Based on this, a raw material screening is carried out in a further step for the development of the repair solutions (3), based on the requirements of the application and the performance criteria of the coating. (4) For the repair of the cracks, a two-stage layer application is aimed at, on the one hand a filling of the cracks and on the other hand a protective coating.

In the material-side development of the repair coatings, the focus is on material compatibility, environmental compatibility (solvent-reduced and halogen-free), adhesion and functionality. This involves characterizing the thermal, mechanical and surface properties of the coatings on the one hand and the weathered backsheet surfaces on the other. After determining the appropriate application method for the newly developed coating solutions, accelerated ageing tests are carried out. In the characterization, which is carried out before and after exposure to stress (moisture, radiation, temperature, condensation, mechanical stress, etc.), the focus is on the interaction between weathered, cracked backsheets and the coating, the repair effect (restoration of electrical insulation properties (Riso), stopping crack growth) and the stress-induced ageing effects. An optical recording system is to verify the stress-induced crack (further) development, as this is an essential indicator of the long-term stability of the repair solution. Electrical measurements (characteristic curve measurement and Riso) before and after the accelerated ageing test will provide further important indicators for assessing the reliability of the repair.

At the end of the project, coating solutions for the repair of PV backsheets for various film materials should be available which, after application and accelerated ageing tests, allow an estimate of the service life extension.

Project management

Dr.Mag. Sonja Feldbacher

Polymer Competence Center Leoben GmbH (PCCL GmbH)

Partners of the project consortium

• Austrian research institute for chemistry and technology (OFI)
• ENcome Energy Performance GmbH
• Sonnenkraft GmbH

Dr.Mag. Sonja Feldbacher
Polymer Competence Center Leoben GmbH (PCCL GmbH)
Sauraugasse 1, 8700 Leoben, Austria
Tel.: +43 3842 429 62-0
E-Mail: office@pccl.at
Web: www.pccl.at