Cracking of solar cells is a serious issue for product safety and module performance. Cracks may result in power loss, hot spots or arcing, and are caused by exceeding the strength limit of silicon. During the last few years, various studies have shown that fracture of encapsulated solar cells can be influenced by the manufacturing processes, which lead to residual stresses in solar cells. The results presented in this paper will give insights into the stresses generated by soldering and lamination. Furthermore, mechanisms of stress generation will be explained. On the basis of these findings, recommendations are made as to how to mitigate stresses, for example by means of alternative soldering processes, different soldering parameters or material optimization of the copper ribbon or the encapsulant.
The main objective of this study was to evaluate the suitability of thermal analysis for characterizing the stage of hydrolytic degradation of PV backsheets containing polyethylene terephthalate (PET) as a core layer. Additionally, the ageing behaviour of single backsheets was compared with that of backsheets incorporated within PV modules. Test modules using identical components (glass, encapsulant, solar cells, etc.), varying only in the type of backsheet used, were fabricated and artificially aged (damp heat:85°C / 85% relative humidity storage up to 2000h). The material characteristics of the single backsheets and module-incorporated backsheets before and after artificial ageing were determined by thermal analysis. It was shown that the most significant changes between unaged and aged sheets can be observed in the cooling curve of the differential scanning calorimetry (DSC) runs. For all materials, a significant increase in the crystallization temperature was found. Furthermore, the results revealed no influence of the PV module lamination procedure on the thermal characteristics of the polymeric backsheets. Even after artificial ageing under damp-heat conditions, differences between single and module-incorporated laminated backsheets were negligible. The ageinginduced degradation effects of PET could be detected by DSC for all the aged sheets. It is therefore proposed that the testing of single PET-based backsheets under accelerated ageing conditions may be a practicable way to investigate the applicability of a new backsheet material for use in reliable PV modules.
In this issue we offer some insights into what the next wave of photovoltaic technologies may look like as that upturn gathers pace. Industry observers have been in broad agreement that the major next-gen PV technology innovations won’t happen straight away. But there’s also little doubt that the search is now on in earnest for the breakthroughs that will come to define the state of the art in the industry in the years to come.
The latest rounds of formal complaints against alleged breaches of trade agreements, the initiation of circumvention investigations, and preliminary announcements and rulings in various countries and trading zones all demonstrate that the multidimensional trade conflict in global PV markets is far from being resolved and is still simmering. The trade dispute is largely focused on the import of downstream products (c-Si wafer, cell and module) in current and prospective high-volume markets, such as the EU, the USA and potentially India. These
nations or trading zones have implemented, or have proposed to implement, anti-dumping and countervailing duties, predominantly targeted against Chinese downstream producers. New rounds of investigations might lead to existing tariffs being extended to Taiwanese manufacturers that directly or indirectly import into the USA, while the EU might scrap a previous quota and minimum price system and revert to tariffs. This paper gives a brief historical review of the global PV trade dispute, and analyses the formal and legal grounding of anticircumvention actions, which in general increase the complexities of business planning. Because more than 70% of the global downstream manufacturing capacity is located in China and Taiwan, the manufacturers in these regions have no choice but to embrace an internationalization strategy that consists of production offshoring. The paper concludes with the introduction of potential strategies and recommendations which take account of
increased complexities and uncertainties in business planning that arise from shifting trade barriers.
Solar companies are always looking for new markets in an effort to remain competitive. Monica Wilson offers some advice on how developers and contractors should navigate the legal labyrinth that will face them as they go global.
Investors are popularly characterised as risk averse and fickle when it comes to new technologies. David Giordano, of the world’s largest asset management firm, BlackRock, tells John Parnell what has persuaded the investment community that solar is a safe bet.
Parallels are frequently drawn between the nascent energy storage business and PV 10 years ago – that it needs strong policy direction to take off. Andy Colthorpe profiles some of the areas that emerging as the world pioneers in supporting the deployment of storage.
Leading US firms SolarCity and SunPower have taken an early position in the fledgling residential energy storage market. Andy Colthorpe investigates how their involvement could shape their own fortunes and that of storage itself.
Investors are looking for steady and predictable returns from their PV plant assets. Ben Willis charts the rise of monitoring technology and how it is becoming an increasingly indispensable part of the PV equation.
