Flexible solar modules are increasingly used in building-integrated photovoltaics, portable applications, and curved surface installations. Unlike rigid glass-based modules, flexible modules must survive repeated bending without losing electrical continuity or developing cracks. The IEC 61215 MQT 22 bending test is designed to verify that a flexible module can withstand this repeated mechanical deformation to the manufacturer's specified radius. Here is a complete breakdown.
What is the MQT 22 Bending Test?
MQT 22, defined in IEC 61215-2:2021, applies exclusively to flexible modules. Its purpose is:
To verify that a flexible module can be rolled up (without damage) to form a radius of curvature defined by the module manufacturer in at least one direction per the manufacturer's specification.
If the manufacturer's installation guide allows bending in more than one direction, the worst-case condition shall be used. The test may be performed on a representative sample.
Note: Once the radius of curvature is defined, the bending stresses are the same as long as the thickness is the same between a representative sample and a longer module.
Required Apparatus
• A cylinder with a diameter of twice the radius of curvature specified by the module manufacturer. The flexible module will be bent over this cylinder.
• Instrumentation to monitor the electrical continuity of the module during the test.
• Environmental conditions for performing the tests: (25 ± 5) °C.
Test Procedure
Step 1 — Set up electrical monitoring
Equip the module so that the electrical continuity of the internal circuit can be monitored continuously during the test.
Step 2 — Roll the module over the cylinder
From a flat/planar starting position, roll the flexible module over the cylinder of the specified radius of curvature. If the module is large enough, it shall roll up on the cylinder in excess of 360°.
Step 3 — Unroll
Unroll the flexible module back to the flat/planar position.
Step 4 — Repeat 25 times
Repeat steps 2 and 3 for a total of 25 cycles.
Final Measurements
After completing all 25 cycles, repeat the following measurements:
• MQT 01 — Visual inspection
• MQT 15 — Wet leakage current test
Pass or Fail Criteria
A module passes MQT 22 if it meets all three of the following requirements:
1. No intermittent open-circuit fault detected during the test when a continuous current is applied and monitored as performed per MQT 11.
2. No evidence of major visual defects, as defined in IEC 61215-1:2021.
3. Wet leakage current must meet the same requirements as for the initial measurements.
Why MQT 22 Matters for Flexible PV Module Certification
Flexible modules face a fundamentally different set of mechanical demands than rigid glass-based modules. Rolling, unrolling, installation on curved surfaces, and repeated thermal expansion and contraction all subject the cell layer, interconnects, and encapsulation to bending stresses that simply do not exist for conventional modules.
A flexible module that passes MQT 22 demonstrates that its cell technology, interconnect design, and encapsulant can withstand the bending radius the manufacturer claims, without cracking, delaminating, or losing electrical continuity. This is particularly important for BIPV applications, lightweight rooftop solutions, and any installation where the module will be flexed during handling or installation.
The 25-cycle requirement also ensures the test is not just a one-off demonstration of bendability but a meaningful fatigue test — repeated bending is closer to real-world conditions where a module may be rolled up and unrolled for transport or storage multiple times over its lifetime.
Need to Find an Accredited Lab for IEC 61215 Testing?
Sinovoltaics Lab Advisor helps you identify and compare accredited test laboratories for PV module qualification testing, including MQT 22 bending testing for flexible modules and the full IEC 61215 sequence. Get connected with the right lab for your project quickly and transparently.
Find your IEC 61215 test lab → labadvisor.sinovoltaics.com
Read more about our Testing articles here.
Source: IEC 61215-2:2021 — Terrestrial photovoltaic (PV) modules – Design qualification and type approval – Part 2: Test procedures, Section 4.22