Controlling Quality

Greater focus needed on improving processes, materials and modules

Working towards its ambitious renewable energy targets, India has progressively increased the volume of renewable energy capacity in the past few years. This expansion is particularly being carried out on the back of the solar segment, which has seen the largest share of capacity expansion. With the current momentum of solar installations, it is becoming increasingly important to maintain quality and reliability of the equipment being used as well as the manufacturing processes being used to produce them. This further requires strengthening of the capacity of quality management systems within the manufacturing ecosystem.

Quality in manufacturing

In solar cell manufacturing, discrepancies can arise in many processes and factors which affect overall efficiency of the cells being produced. There are several stages at which contamination as well as other problems can arise along the production chain. Initially, silicon is tested for purity, crystal orientation and resistivity. Manufacturers also have to look out for the presence of oxygen and carbon. While the former affects the strength and resistance to warp, the latter causes defects. Further, the finished silicon disks must be inspected properly for any damage, bending or flaking. While manufacturing silicon disks, factors such as temperature, pressure, speed and quantities of dopants must continuously be monitored.

Small particles can adversely affect the manufacturing process. Thus, measures must be taken to ensure that impurities present in the air are kept to a minimum. Clean rooms are set up in manufacturing spaces to address the issue of controlling the environment in the area where production is taking place. A clean room is a contained space where provisions are made to reduce particulate contamination and control other environmental parameters such as temperature, humidity and pressure. One of the features often used in clean rooms is the high efficiency particulate air (HEPA) filter for trapping particles that are 0.3 micron and larger in size. In some cases where stringent cleanliness performance is necessary, ultra low particulate air filters are used. The working personnel undergo extensive training in contamination control theory. They enter and exit the clean room through airlocks, air showers or gowning rooms, and must wear special clothing designed to prevent contaminants from affecting the environment. In order to maintain quality of manufacturing, it is essential to make sure that proper protocol is followed.

The manufacturing unit should also monitor the performance and accuracy of the equipment used in the production process. The organisation should also inspect the product in process in addition to performing a final inspection to ensure that the requirements of the product specification are met and defective products are prevented from release.

Standards, testing and certification

A lapse in quality control in the manufacturing process further results in solar modules that are not as efficient and do not meet standards. Although there are international standards for quality assurance, these must be aligned with meeting performance requirements for local climatic conditions and the life of a product. In order to effectively carry out such testing, there is a need for proper infrastructure such as test laboratories, which are equipped with modern equipment and instrumentation. Further, technically trained professionals who can adopt scientific methodology and are able to properly carry out test protocols will be essential to such practices.

The way forward

The scale at which solar power systems are being deployed warrant more emphasis on quality control. As the Indian solar market is expanding, especially with more solar module manufacturers entering the domestic market,  there is an urgent need for accredited testing centres as well as for strengthening quality management systems for manufacturing units. Solar components such as modules are assumed to have a typical life of about 25 years. However, recent studies such as one carried out by NISE and IIT Bombay draws attention to significantly high module degradation, which can be a cause for concern. This can have a financial impact due to the loss of revenue and added costs of replacing early defecting modules. It will also add to the amount of solar panel waste being generated, which is a concern as recycling units have not been established at scale.

In sum, to make way for the upcoming solar power expansion in the country, there must be an increased focus on improving processes, subassembly, and the quality of material used and the final components. While cheap imported products with suboptimal quality have been commonplace in installations so far, this should not be the norm moving forward, especially in light of the shift to domestic manufacturing.

By Meghaa Gangahar

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