Laser doping is discussed often in relation to silicon photovoltaic cell efficiency enhancement. However, the specific use of lasers for dopant diffusion falls within a broader category of ‘Laser-Assisted Selective Emitters’. Understanding the benefits enabled by laser tools here is important not just in explaining what laser doping is, but why laser processing features in most selective emitter concepts.
With the ever-growing challenge of remaining financially viable in today’s economic climate, some companies in the PV industry are adapting and applying the structures and principals of project finance to the photovoltaic assets. The purpose of project finance is to create a business structure which brings together multiple entities, aligns their interests, and allocates the project’s inputs and outputs (i.e. risks and rewards) in such a way that the overall benefits derived from the project are maximized.
The process of wafering silicon bricks into wafers represents about 20% of the entire production cost of crystalline silicon solar cells. In this paper, the basic principles and challenges of the wafering process are discussed. The multi-wire sawing technique used to manufacture wafers for crystalline silicon solar cells, with the reduction of kerf loss currently representing about 50% of the silicon, presents a major challenge for further research efforts. Another relevant field of research is the reduction of wafer thickness in order to obtain more wafers per millimetre of brick length. The last subject that is addressed in this paper is the general optimization of the wafer surface and geometry, as the multi-wire saw cutting process influences the mechanical properties of the wafers and can have further effects on subsequent process steps.
Among the different packaging materials used in photovoltaic solar modules, ethylene vinyl acetate-based (EVA) encapsulants play an important role during the lifespan of the module assembly. Prior to lamination, EVA is a thermoplastics polymer containing a number of additives. During the lamination process, EVA cross-links into a three-dimensional network structure, i.e., a thermoset, which provides protection for solar cells against detrimental environmental conditions. Since EVA has a very low glass transition temperature and melting points, proper cross-link density has to be achieved through the lamination process to prevent the EVA from cold flowing in the field. As a result, module manufacturers constantly monitor the cross-link density or gel content of EVA after lamination. This paper proposes a new method of measuring this density value while avoiding many of the current pitfalls.
Efficient management of the PV supply chain can save a company money, both directly by reducing material and component cost, and indirectly by improving lead time, inventory optimization and quality throughout the entire value chain. So-called static supply chains compare poorly to their dynamic counterparts that see cost reduction and quality as well as material availability improvements. What follows is a proposal of improving the supply chain using methods like integration, data exchange and collaboration that can also help to improve entire E2E flows through re-structuring and outsourcing from one level to another.
Until the year 2002, wafer-based crystalline silicon solar cells were almost exclusively the solar cell technology used for large-scale power plants. Since then, steady growth in the market share for thin-film technologies has been observed, although crystalline silicon technology still remains the most important solar cell technology used in large-scale PV power plants. The market share of thin-film modules, especially CdTe modules, has been continuously increasing in recent years, most notably in the German market. However, other countries like Spain, the USA, Italy and France have seen some large-scale CdTe-based modules being installed in power plants recently.
Wet processing can be a very high performing and cost-effective manufacturing process. It is therefore extensively used in Si solar cell fabrication for saw damage removal, surface texturing, cleaning, etching of parasitic junctions and doped oxide glass. PV manufacturers have succeeded in bringing down the cost of ownership of batch-type and in-line tools. The trend to back-side passivated solar cells requires cost-effective single-sided processing solutions. With the future pointing to ever-thinner silicon solar cells, handling these thin wafers in wet environments is a major challenge for any wet process. This paper reviews the major wet processing steps, emphasising some new developments and unknown issues, and provides a more general outlook on trends in wet processing.
Solar enterprises will each be faced with the occasional surplus or lack of solar modules in their lifetimes. In these instances, it is useful to adjust these stock levels at short notice, thus creating a spot market. Spot markets serve the short-term trade of different products, where the seller is able to permanently or temporarily offset surplus, while buyers are able to access attractive offers on surplus stocks and supplement existing supply arrangements as a last resort.
The photovoltaic market is currently experiencing a rapid decline in average selling price per module, resulting in a new era of challenges to reduce the investment and operational costs of manufacturing facilities. Subsequently, PV modules are rapidly gaining acceptance for industrial applications in the renewable energies sector. The PV industry will therefore need to progress toward high volume production of the established process technologies to meet future demand after the current inventory base has been installed. This paper addresses the potential impact of process technology, manufacturing and automation considerations, as well as the appropriate building concepts for large-scale crystalline silicon cell manufacturing. The other inherent advantages and considerations regarding fabs with a capacity approaching one gigawatt peak are also evaluated and discussed based on comparisons between two actual production facilities.
The global PV market is undergoing fundamental change. According to a new survey by EuPD Research, Germany is once again the most important PV sales market worldwide this year. Current market conditions are tightening, but within Germany there is still plenty of undiscovered potential. The transformation of the PV market from a supply-driven sellers’ market to a demand-driven buyers’ market is, however, an accelerated process rather than a slow development.
