Solar modules are increasingly considered to be a long-term investment and therefore, a number of prerequisites apply, including performance guarantees, quality assurances, commercial certainty, return on investment and long-term viability.

Q-Cells was the first solar manufacturing company to participate in the Association of German Engineers (VDE) Quality Tested program. Q-Cells took ensuring its solar module quality a step further and devised its own Triple Yield Security Seal to address three main module concerns: 1) potential induced degradation (PID), 2) hot spots and 3) traceable quality control.

Below is an outline of the rigours of securing the quality of Q-Cells solar modules.

Independent testing and standard credentials

Most modules comply with International Electrotechnical Commission (IEC) standards, particularly the solar IEC 61215 and IEC 6173 standards, which include thermal cycling, mechanical load testing, hot spot testing, measurement of temperature coefficients and minimum performance requirements. Most manufacturers exceed these testing requirements and therefore, IEC standards can be considered an essential for when assessing the quality of a module.

A solar module should be able to reliably produce electricity for at least 25 years in all climate zones of Australia. Some conditions, however, are particularly challenging for solar modules, such as extreme heat, high humidity, salty coastal climates and cyclonic winds.

Therefore, the German independent certification authority VDE has developed a Quality Tested program to ensure that reliability expectations are met. The approval certification, the quality controls during the production process, frequency and length of the testing cycle, and the low acceptable performance loss threshold of 5 per cent (compared to 8 per cent by IEC) make Quality Tested by VDE one of the most comprehensive testing programs for solar modules.

The comprehensive tests guarantee high reliability, optimised durability and low degradation thanks to continuous line monitoring which leads to high production consistency and results in high-quality modules – every time and at all production sites.

Triple Yield Security Seal

Beyond VDE testing, Q-Cells has also developed its own Triple Yield Security Seal for its crystalline modules, to ensure quality and address three main concerns:

• PID
• Hot spots
• Continuous quality control.

PID

Due to the leakage of currents at high voltages, PID can cause significant yield losses of up to 20 per cent over the life of a system. In addition to high voltages, PID severity depends on temperature and relative air humidity, which can both accelerate the amount of leakage current. Through two years of research, Q-Cells have developed a number of highly optimised processes to tackle the issue of PID and eliminate the problem from their products.

Hot spots

Hot spots originate during the production process, namely when solar cells are subject to stress, which causes defects undetectable to the naked eye. Under certain conditions, such as partial shading, those defects can heat to temperatures of up to 250˚ Celsius. These extremely high temperatures within a module can cause substantial power loss and even lead to permanent module failure.

As part of the Triple Yield Security Seal requirements, modules are tested under extreme climatic conditions up to three times, and solar cells are individually inspected throughout the production process in order to eliminate those which may be damaged.

Continuous quality control

Q-Cells oversee the entire production process of its cells and modules, and are sure to document every step of this process. The inclusion of digital signatures enables the full traceability of major parts, including silicon cells and solar modules and systems.

Before entering the production process, every Q-Cells solar cell gets a distinct Data Matrix Code, applied by a unique Traceable Quality (Tra.QTM) laser marking technology. The code relates key data to the individual cell, including delivery date of the raw material, supplier code and codes of materials used across the production process. This allows for continuous process optimisation, leveraging cost benefits and advancing technological innovations in the solar industry.

At Intersolar 2011, Semiconductor Equipment and Materials International, a leading international standardisation body in the field of semiconductors and photovoltaic (PV), recommended making Tra.QTM an industry standard.

Result: 29 per cent higher yields

Q-Cells goes to the above described testing lengths to ensure that investors and endcustomers receive an expected return on their investment as a result of high, reliable electricity output over the full lifetime of their PV system – up to 29 per cent more over 25 years.

Thomas Raadts, Senior Vice President, Marketing and Product Management, at Q-Cells SE says: “We want to guarantee the highest yields for our customers. This is why we are offering an integrated package of measures that improve quality and performance, unlike any other manufacturer.”