Photovoltaics International Papers

Crystalline silicon wafer technology currently dominates industrial solar cell production. Common devices feature opposing electrodes situated at the front and the rear surface of the wafer, and subsequent front-to-rear interconnection is used for module assembly. This paper describes the status and perspectives of the emitter wrapthrough (EWT) cell concept, which is a fully back-contacted solar cell. The functions which have to be fulfilled for this concept, as well as the corresponding challenges and advances, are discussed.

Silver paste is a key component of the design of nearly all silicon wafer solar cells manufactured in 2011. The high cost of the precious metal in the paste formulation means that silver paste is also the second-highest component of the total cost of materials. This article reviews the silver paste supply chain and the challenges in silver paste formulation and manufacture, and discusses some of the approaches for reducing or removing entirely the use of silver in crystalline silicon cell manufacture.

The reliable analysis of trace elements in silicon is of fundamental importance for the understanding of material properties and quality control of solar cells. This paper presents a demonstration of the power of two analytical techniques for the determination of trace elements in solar silicon: inductively coupled plasma mass spectrometry (ICP-MS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). These techniques are among the few that achieve sufficiently low detection limits and they may complement each other because of their specific performance. Examples are given of the quantitative chemical analysis of boron, phosphorus and iron in different types of solar silicon, as well as of the enrichment of metals and alkali metals in Si3N4 precipitates.

How much carbon is emitted in producing a solar PV module and launching it on the market? This could be an important question which project developers, installers, investors, government agencies and end customers might ask solar PV manufacturers in the future. To answer it, producers need to know the direct emissions from the manufacturing process, as well as those generated from the activities of manufacturers in the upstream supply chain (including raw material acquisition, upstream energy use, packaging, transportation and procurement), and also those arising from module usage and eventual recycling. This paper, written in a cooperation between EuPD Research and Deutsches CleanTech Institut (DCTI), presents an overview of PV’s carbon footprint.

In the photovoltaic industry, laser edge isolation (LEI) is a well-established process at the end of the process chain. However, because the cell properties vary from one cell producer to the next, no systematic approach is defined in industry for establishing an efficient isolation groove. Nevertheless, a general approach has to be defined for analyzing the LEI process for silicon solar cells. Besides the material aspects and laser parameters, atmospheric boundary conditions must be considered. This paper presents investigations into the ablation of a specific type of mc-silicon solar cell, and the most suitable laser, as well as the ambient parameters, is determined based on the results of the experiments.

For a vertically integrated solar cell production starting with purification of silicon feedstock and ending with the production of solar cells, it is necessary to have control over all possible parameters that may affect yield, efficiency and product quality. This paper presents an approach for tracking products with minimal effort using a contactless technique. The method allows wafers to be virtually reconstructed into bricks and ingots, as well as recognizing the precursor wafer for each solar cell.

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 stock levels for modules at short notice, thus creating a spot market. Spot markets serve the short-term trade in different products, by enabling the seller to permanently or temporarily offload surplus, while buyers are able to access attractive offers on surplus stocks and supplement existing supply arrangements as a last resort.

A new production process for crystalline silicon (c-Si) solar cells, specifically p-type back-contact solar cells, is proposed. In contrast to the conventional c-Si solar cell manufacturing method, this new technology eliminates the etching process and reduces the industrial three-step electrode printing to only one step, greatly improving the technological process. Furthermore, the proposed process is also largely compatible with a traditional c-Si solar cell production line. Oxidation technology for producing the SiO2 film on a c-Si wafer, together with corrosive window technology, such as through HF corrosive paste screen printing, for creating the patterning on the wafer covered with SiO2 film, are used in the fabrication of the p-type back-contact solar cells.

In recent years solar photovoltaic electricity has shown a steady decrease in cost, thanks to technological improvements and economies of scale. Over the last 20 years the price of PV modules has dropped by more than 20% each time the cumulative volume of PV modules sold has doubled. System prices have fallen accordingly: during the last 5 years a price decrease of 50% has been seen in Europe. This trend will continue in the foreseeable future. System prices are expected to fall in the next 10 years by 36–51%, depending on the segment. Importantly, there is a huge potential for further reductions in generation costs: around 50% by 2020. The cost of PV electricity generation in Europe could decrease from 0.16–0.35€/kWh in 2010 to 0.08–0.18€/kWh in 2020, depending on system size and irradiance level. That decline in cost will continue in the coming years as the PV industry progresses towards becoming competitive with conventional energy sources. Under the right policy and market conditions, PV competitiveness can be achieved in some markets as early as 2013, and then spread across the Continent in the different market segments by 2020. This paper summarizes the first part of a newly published EPIA report about PV competing in the energy sector. The report illustrates why PV can become a mainstream player in the energy field before 2020. The study, carried out with the support of the strategic consulting firm A.T. Kearney, shines new light on the evolution of Europe’s future energy mix and PV’s role in it.

The solar industry suddenly finds itself in an altered business climate in which construction markets seem permanently damaged and government subsidies are under challenge. This paper outlines how BIPV provides a strategy for expanding the market for PV and creating value-added products in a radically changed political, economic and financial environment.