Solar Module Test

Solar Module Test

Solar energy is a kind of renewable energy, refers to the sun's thermal radiation energy, the main performance is often said that the sun rays, in the modern generally used for power generation or to provide energy for water heaters. In the case of decreasing fossil fuels, solar energy has become an important part of human energy use and continues to develop. The use of solar energy has two ways of photothermal conversion, solar power generation is an emerging renewable energy, so the related solar energy research and application industry has also stepped up the pace of development. In the research and production process of the solar module, the relevant reliability test and environmental test specifications have been formulated to ensure that the solar module can be durable for more than 20 to 30 years and its power generation conversion rate when used in outdoor environment.

Solar module HAST and PCT test illustration

Temperature and humidity test IEC61215-10-13:

Temperature and humidity test  conditions are 85℃/85%R.H., time: 1000 hours, to determine the ability of the module to resist long-term moisture penetration, through the temperature and humidity test  can be found defects: CELL delamination, EVA(delamination, discoloration, bubble generation, atomization, Browning), string line blackening, TCO corrosion, solder joint corrosion, Thin-film yellow discoloration, junction box degumming off... However, according to the test results of relevant Solar plants,1000 hours is not enough, and the actual situation finds that the test time to enable the module to find the problem needs to be at least 3000 to 5000 hours.

Test method of HAST [Highly Accelerated Temperature and Humidity Stress Test]:

HAST is short for Highly Accelerated Temperature and Humidity Stress Test in English. The highly accelerated humidity resistance evaluation test method is based on the environmental parameters of temperature and humidity. HAST and PCT [Pressure Cooker Test] are different from the two tests, HAST is called unsaturated test, while PCT is saturated humidity test, and the biggest difference from the general humidity evaluation test method is that it is in the field of temperature and humidity above 100℃, and is in the high-density water vapor environment test. The purpose of HAST is to accelerate the test of humidity intrusion into the sample for humidity resistance evaluation by taking advantage of the fact that the water vapor pressure in the test tank is much higher than the water vapor partial pressure inside the sample.

Test specifications and conditions of JESD22-A118[Accelerated Moisture Resistance-Unbiased](HAST unbiased test) :

It is used to evaluate the reliability of the device in wet environment, that is, the penetration of harsh temperature, humidity and increased water vapor pressure through the external protective material (encapsulation or sealing material) or along the interface of the external protective material and metal conductor, the failure mechanism is the same as that of the [85℃/85%RH] high temperature and high humidity steady-state humidity life test (JESD22-A101-B). In this test process, no bias is applied to ensure that the failure mechanism is not covered by bias, and this test is used to determine the failure mechanism in the package. The sample is in a non-condense humidity environment, only the temperature is increased a little, and the failure mechanism is the same as the [85℃/85%RH] high temperature and high humidity steady-state humidity life test without bias. It should be noted that, Since absorbed water vapor reduces the glass transition temperature of most polymer materials, an unreal failure mode may occur when the temperature is higher than the glass transition temperature.

85℃/85%/1000H(JESD22-A101)→110 ℃/85%/264H(JESD22-A110, A118)

Specifications: JEDEC22-A110(with bias), JEDEC22-A118(without bias)

Common conditions: 110℃/85%R.H./264h Applicable: PET, EVA, modules

Test method of PCT [Pressure Cooker Test]:

Generally known as the pressure cooker cooking test or saturated steam test, the most important is to test the product under harsh temperature, saturated humidity (100%R.H.)[saturated water vapor] and pressure environment, test the high humidity resistance of the test product, for solar packaging materials or modules, used for material moisture absorption test, high pressure cooking... For the purpose of the test, if the product to be tested is a Cell, it is used to test the moisture resistance of the Cell. The product to be tested is placed in a harsh temperature, humidity and pressure environment for testing. If the package is not well packaged, moisture will penetrate into the package along the colloid or the interface between the colloid and the wire frame. Popcorn effect, open circuit caused by metal wire corrosion, short circuit caused by contamination between package pins... And other related issues, and HAST accelerated aging is not the same.

Test specifications and conditions of PCT JESD22-A102:

To evaluate the integrity of non-airtight packaged devices against water vapor in a condensed or saturated water vapor environment, the sample is placed in a condensed, high-humidity environment under high pressure to allow water vapor to enter the package, exposing weaknesses in the package, such as delamination and metallization layer corrosion. The test is used to evaluate the new package structure or the update of the material and design in the package body. It should be noted that some internal or external failure mechanisms will appear in the test which are not consistent with the actual application situation. Since absorbed water vapor reduces the glass transition temperature of most polymer materials, an unreal failure mode may occur when the temperature is higher than the glass transition temperature.

Test conditions: 121℃/100%R.H./80h(COVEME), 200h[toyalSolar]

Applicable: PET, EVA, modules

Pressure cookers (PCTS) and Highly Accelerated Life Test Equipment (HAST) :

At present, most solar materials and modules can withstand long-term DHB(temperature and humidity + bias) test without failure, in order to improve the test efficiency and shorten the test time, the pressure cooker test method is used. Pressure cooker test methods are mainly divided into two types: That is, PCT and HAST, if the defects of solar packaging materials and modules can be found through HAST tests, and the degradation can be reduced by 1%, the LCOE[Levelized Cost of Electricity(actual energy output value, power generation cost per KWH)] will be reduced by 10%. The purpose of the PCT test is to increase the ambient stress (temperature & humidity), and to evaluate the sealing effect of the module and the moisture absorption of the backplane by exposing it to a wetting vapor pressure of more than one atmosphere.