Solar glass, as a crucial component of photovoltaic modules, has a direct impact on the power generation efficiency and service life of photovoltaic systems. To ensure that its quality meets industry standards, it undergoes a series of rigorous inspection processes. This article systematically explains the key inspection steps and technical highlights for solar glass.
Appearance Inspection
Appearance inspection is the initial step in solar glass quality control. It primarily inspects the glass surface for defects using visual inspection or automated optical equipment. Inspection items include bubbles, scratches, stones, inclusions, and edge chipping. Standards require that the glass surface be free of visible defects, and that the length and depth of scratches comply with industry standards (such as IEC 61215). Automated inspection systems typically use high-resolution cameras combined with image recognition algorithms to improve inspection accuracy and efficiency.
Dimension and Shape Inspection
The dimensional accuracy of solar glass directly impacts its compatibility with photovoltaic modules. Inspection items include length, width, thickness, and diagonal deviation. Conventional inspection methods use laser rangefinders or CNC measuring instruments to ensure that the glass's dimensional tolerances are within ±0.5 mm. Flatness testing is also crucial. Typically, an optical interferometer or level is used to measure the flatness of the glass surface to ensure it meets the warpage requirement of ≤0.3%.
Optical Performance Testing
Optical performance is a core indicator of solar glass, directly impacting light transmittance and energy conversion efficiency. Key testing items include:
1. Transmittance Testing: A spectrophotometer is used to measure the transmittance of the glass within the 300-1100 nm wavelength range. The standard requires a visible light transmittance of ≥91% (single-silver Low-E glass) or higher (double-silver/triple-silver coated glass).
2. Haze Testing: A haze meter is used to assess the proportion of scattered light on the glass surface. The haze value must be ≤1% to ensure uniform light transmission.
3. Reflectance Testing: Measure the reflectivity of sunlight on the glass surface. Optimizing reflectivity can reduce light energy loss.
Mechanical Performance Testing
Solar glass must possess sufficient mechanical strength to withstand environmental stresses. Key testing items include:
1. Impact Test: According to IEC 61730, a 227 g steel ball is dropped from a height of 1 m to test the glass's resistance to shattering.
2. Flexural Strength Test: The glass's modulus of rupture is measured using a three-point bending tester to ensure it meets the requirement of ≥90 MPa.
3. Tempering Performance Test: For tempered glass, the fragmentation state (≥40 fragments per piece) and surface stress (≥90 MPa) must be verified.
Environmental Performance Testing
Solar glass is exposed to outdoor environments for long periods of time, making weather resistance testing essential:
1. Humidity Test: A 1000-hour aging test at 85°C and 85% RH is conducted to evaluate the glass's resistance to humidity and heat.
2. UV Exposure Test: A UV aging chamber is used to simulate over 2000 hours of UV radiation to test the coating's resistance to degradation.
3. Acid/Alkali Resistance Test: Immerse the glass sample in an acid solution with a pH of 2 or an alkali solution with a pH of 10 for 24 hours and observe surface corrosion.
Electrical Performance Testing (for Coated Glass)
If the solar glass has a conductive coating (such as TCO coating), parameters such as sheet resistance and combined transmittance and conductivity must also be tested. Sheet resistance testing typically uses a four-probe method to ensure that the coating's resistance is uniform and meets design requirements (e.g., ≤10 Ω/sq).
Conclusion
The solar glass testing process covers multiple dimensions, including appearance, dimensions, optics, mechanical properties, environmental resistance, and electrical properties. Each step must strictly adhere to international or industry standards (such as IEC and ASTM). Through systematic testing methods, high-quality solar glass that meets requirements can be effectively selected, ensuring the long-term stable operation of photovoltaic modules. In the future, with the advancement of photovoltaic technology, testing methods will further develop towards intelligent and high-precision methods.
