Thermal Cycling Test of PV Panels

The purpose of the thermal cycle test is to determine the component's thermal mismatch stress, fatigue, and other abilities caused by repeated temperature changes. Thermal cycling test is definite requiremented in several test standards, including IEC61215 (Crystalline silicon photovoltaic modules for terrestrial use-design qualification and finalization), IEC61646 (Thin film solar module test standard), IEC62688 (Concentrator CPV modules and components-safety certification) and IEC62108 test standard.

Required Conditions for test equipment

a) A climate chamber, with automatic temperature control, make the internal air circulation and avoid moisture condenses on the surface of the component, in the process of test device, and can swim at one or more components are shown in figure 1 thermal cycling test.
b) In the climate chamber is installed or supporting components of the device, and to ensure that the air around can free circulation, installation or supporting device of heat conduction is small, so in fact, should make components in the insulation state.
c) Measure and record the component temperature instrument, the accuracy of ±1 ℃, the temperature sensor should be placed in a central component of surface before or after. Such as multiple components test at the same time, a representative need to monitor the temperature of the component.
d) In the process of test, the group with access to equal to the maximum power point of standard test under the condition of current equipment.
e) In the process of test, monitoring through each component of current instruments.

Test procedure step:

I) Assemble the components in the climate chamber at room temperature. If the component's border does not conduct well, install it on a metal frame to simulate an open support frame.

II) Connect the temperature sensor to the temperature monitor, connect the positive terminal of the module to the positive electrode of the current meter, and connect the negative electrode to its negative electrode. In the 200 thermal cycle test, connect the module with the maximum power point current under standard test conditions ±2%, only when the component temperature problem exceed 25℃ keep the flow of electric current, 50 times thermal cycling test does not require through current.

III) Closed gas machinery room, according to the distribution of figure 1, to circulate the temperature of the components between 40℃±2℃ and +85℃±2℃, temperature change rate can't exceed 100℃/h, in every extremely temperature, should remain stable for at least 10 min except the components of the heat capacity greatly need longer time to insert ring, one cycle time no more than 6 h, the number of cycle corresponding side is shown in figure 1.

                                                                    FIGURE 1

IV) In the process of the whole test, record the temperature of the component, and monitoring by component of current. Note, in a parallel way components branch will cause the discontinuity of voltage, but does not cause 0.