Photovoltaic, or photovoltaic power generation system, is a power generation system that uses the photovoltaic effect of semiconductor materials to convert solar radiation energy into electrical energy. The energy of photovoltaic power generation system comes from the inexhaustible solar energy, which is a clean, safe, and renewable energy source. The photovoltaic power generation processes。
EVA film: EVA film for solar cell encapsulation is a widely used material for the internal encapsulation of photovoltaic modules. As an extremely important part of the PV module, EVA film can resist the influence of the external environment on the performance of the cell and damage to the cell to play a protective role.
Solar backsheet: also known as photovoltaic backsheet, which is located at the back of the solar panel, plays a protective and supporting role for the cell, with reliable insulation, hydrolysis resistance, UV resistance and electrical and thermal aging. Its structure is composite for the mainstream technology, PVDF is the mainstream material.
Popular applications for lithium-ion batteries
Ethylene-vinyl acetate copolymer EVA
The adhesive film is the key material for PV module encapsulation. The operating life of PV modules is 25 years. The performance indexes of PV encapsulation film, such as light transmission, shrinkage, peel strength and aging resistance, are crucial to the operation of modules. If the film is yellowed and cracked during the operation of the power plant, it will lead to cell failure and scrap, directly affecting the module's power generation efficiency. Therefore, although the cost of adhesive film is not high in absolute value, it directly determines the quality and service life of PV modules.
Ethylene-vinyl acetate copolymer molecular formula
EVA key performance requirements: light transmittance, shrinkage, peel strength, aging resistance, etc.
EVA film is mainly composed of EVA resin, plus a variety of additives, such as crosslinkers, thickeners, antioxidants, light stabilizers, etc. EVA with its excellent encapsulation performance, good aging resistance and low price and other advantages, it has become the preferred material for PV module encapsulation before 2014. The disadvantage is the lack of anti-PID performance.
Solar Backsheet
The composite process is the mainstream technology for PV backsheets, which generally has a three-layer structure (PVDF/PET/PVDF). The outer PVDF fluorine film needs to have good resistance to environmental erosion, the middle PET base film has good insulation performance, and the inner PVDF fluorine film has good bonding performance with PV adhesive film, while the layers need to be bonded with adhesives to prevent peeling between layers, thus ensuring the long-term reliability of the modules.
Solar back sheet test items and standardsGB/T 31034-2014 Insulated back sheets for crystalline silicon solar cell modules;
T/CPIA 0029. 1-2022 Films for back sheets of photovoltaic modules part 1:Fluoroplastic films;
GB/T 13542.2-2009 Films for electrical insulation Part 2: Test methods.
GB/T 36802-2018 Adhesives for solar photovoltaic back sheet laminates;
Backplane water vapor transmission rate
According to the provisions of GB/T 26253-2010. Test on three specimens, the results take the median value, and report the maximum value. In the experimental conditions 38 ℃, 100% RH, composite, and coated back sheet limit value requirements ≤ 2.5 g/m2-d.
Test procedure: use the standard membrane to calibrate the instrument, use the circular sampler to cut the sample, apply the membrane sealing grease on the cavity, inject 20-30mL of pure water into the middle of each cavity with a syringe, then put on the cavity cover and start the test.
Test range 0.002~200 g/(m²-24h)
Resolution 0.0001 g/(m²-24h)
Test area 50.24 cm²
Specimen size Φ100 mm
EVA, backsheet heat shrinkage rate
EVA test method: Super white embossed tempered glass 120 ℃ oven preheating, after the specimen spread on the glass, heated for 3min and then removed, cooling measurement.
Tensile strength, elongation at break, peel strength
Product functions:
1、Tensile test: The results can be measured as maximum force, maximum deformation, tensile strength, elongation, yield force, yield strength, modulus of elasticity, etc.
2, peel: can do conventional peel, 90 ° peel, 180 ° peel.
3、Ball screw drive, imported servo motor.
4、Equipped with professional pneumatic stretching fixture
EVA density
GB/T 29848
Density: Transparent EVA 0.90-0.98g/cmm³ White EVA 0.90-1.10g/cm3
DH-300 solid density meter
A density measuring instrument combined with electronic balance, density software, density accessories, etc.
Measuring accuracy: 0.001 g/cm3
Range: 0.001~99.999g/cm3
Light transmittance (transparent EVA)
GB/T 29848
Transparent EVA transmittance: 1) 380nm~1100nm ≥90.5%
2) 290nm~380nm UV high transmission type ≥ 70% UV cut-off type ≤ 30%
Necessity: Light transmission is an important index to characterize the optical properties of EVA film, and is one of the important indexes to evaluate the quality of the product.
SGW-810 transmittance / haze meter has the following features:
-Adopts parallel illumination, hemispherical scattering, and integrating sphere photoelectric receiving method.
-Transmittance results are directly displayed to 0.01%.
-Adopts microcomputer automatic operating system and data processing system, and the function of storing on a USB flash drive.
-Due to the use of modulator, the instrument is not affected by the ambient light and does not need to use a dark room.
EVA, back sheet UV aging performance, high temperature, and high humidity aging
EVA GB/T 29848
UV aging performance (120kWh/m²), high temperature and high humidity aging performance (DH1000h).
Peel strength>30N/cm, yellowing index △YI difference <5.0
Backing plate GB/T 31034-2014
UV aging performance (30/45/60 kWh/m²), high temperature and high humidity aging performance (1000h/2000h/3000h), yellowing index △YI difference <3
