The Mechanical Load Test is performed to determine the ability of the PV module to withstand static snow and wind loads. Certification standards require to test the effects of wind and snow loads on PV modules.
The mechanical load test is usually performed at room temperature, with the module mounted horizontally and the artificial force placed vertically on the solar panel. ]
Mechanical load test, source: PSE
These test conditions are not realistic as snow loads do not occur at room temperature and wind does usually not blow vertically on the PV modules. A solution is to use a special climate chamber that allows simulating temperatures. Alternatively a complementary field test is always recommended. The test is performed as following: 3 cycles of 1 hour 2400 pa in pressure, and 3 cycles of 2400 pa in traction. To stimulate large snow loads, 5400 pa is used during the last pressure cycle.