Solar Panel Peel Testing

Solution

• Semi-automated, repeatable testing in line with international standards.
• Data acquisition for quantitative comparison of samples.
• Single system capable of testing multiple layers within composite PV modules.

Benefits

• Software-controlled tensile tester.
• Pinch grips designed for handling thin sheets and foil specimens.
• Peel table fixture for 90° peel tests.

Requirement

A solar panel (a photovoltaic PV module) is capable of working under extended conditions of extremely high and extremely low temperatures, ultraviolet radiation, precipitation, ice, and wind. During the lifecycle, the module has to maintain mechanical and electrical integrity. In the solar industry, peel testing is a key mechanical evaluation, particularly for multi-layer laminated modules.

Peel tests primarily assess the adhesion of interconnection ribbons to the metallized surface of solar cells. The common specimens are small ribbons made of copper and attached to crystalline silicon substrates. Peel or fracture pattern forces are measured to obtain important quality indicators to reject or accept cell types, to confirm metallization paste or conductive adhesives, or to optimize production processes, including soldering, tabbing, or stringing.

Peel tests are also performed on PV laminate interfaces, including encapsulant polymers (EVA) and protective back sheets. Any delamination can compromise corrosion resistance, allowing moisture ingress or oxidation, which reduces module efficiency. The 90° peel resistance tests used on these interfaces are described in standards ASTM D6862-11 and BS EN 28510-1 to provide similar and consistent results.

Solution Implementation

A motorized tensile tester (such as the OmniTest or MultiTest systems of Presto Stantest) equipped with the correct load cell, thin-sheet grips, and software to produce peel force graphs is used to test it. The angles of peel are 45°, 90°, and 135°, which are applied depending on the application, and test speed has a substantial impact on the results, and therefore, the parameters should remain constant to make meaningful comparisons.

EN 50461 and IEC 61730-2 international standards specify a test peel speed and angle of 50 mm/min and 90 deg., respectively, of soldered or glued ribbons with a minimum peel strength of 1 N/mm in width. With the software, the manufacturer can construct a library of test routines that would allow them to repeat adhesion testing of various layers of the PV module. The grips or the fixtures can be changed easily, and they can be quickly and reliably tested on a variety of samples.

Test Equipment

• OmniTest/MultiTest 2.5 software-controlled tensile tester.
• VectorPro or Emperor Force software for data acquisition.
• Pinch grips for thin and foil specimens.
• Peel table fixtures for 90° testing.

Applicable Standards

• IEC 61730-2 – PV module safety qualification, Part 2: Testing requirements.
• ASTM D6862-11—90° peel resistance of adhesives.
• BS EN 28510-1 – Peel test for flexible-bonded-to-rigid specimens at 90°.