Photovoltaics International Papers

During the severe plummet of PV prices that took place during 2008–2012 as a result of overcapacity, the polysilicon sector suffered a major adjustment of costs and capacity to face the reduction in prices and the mismatch between demand and supply. In 2012 that significant drop in prices provoked the bankruptcy of many polysilicon producers, with only the large and efficient players still surviving. However, there was also an impact on the (at that time) promising and immature industry of metallurgical purification of metal silicon, also known as upgraded metallurgical-grade silicon (UMG-Si). The strong selling point of UMG-Si producers – the production costs – was no longer an asset, leaving UMG-Si with nothing but its weakness – the quality. The generation costs for solar energy are currently comparable to those for conventional fuels. The solar industry is self-sustaining and is not dependent on government subsidies. In this current situation, the industry requires an updated comparison between the two main routes of silicon purification and their products, which is the aim of this paper.

The production toolset is not the only significant source of power consumption in PV cell production. Cooling water, climatization, pressurized air and, in some cases, clean-room conditions drive up the electrical energy demand, while geographical location also has an influence. The extent of this additional consumption over and above the toolset is demonstrated by a number of quantitative examples in this paper.

In this quarterly report a full analysis is given for the first time of two years’ worth (2014-15) of PV manufacturers’ capacity expansion announcements as well as an assessment of announcements that have or are planned to convert to effective new nameplate capacity through to the end of 2016. The analysis provides the first insight into new capacity ramp profiles of effective capacity expansions over the last two-year period and highlights future ramp profiles expected through to the end of 2016.

The solar industry is going through the final stages of correcting its supply–demand imbalance, with the decision-making on technology choice for the next generation of GW-scale factory expansions becoming a key strategic issue for leading manufacturers. In contrast to previous capacity expansion phases – where new entrants largely copied known process flows and technology types – the next round of technology additions is seeing a broader range of influences, indicative of a new type of technology roadmap unfolding for the industry as a whole.

The backsheet is the first barrier for ensuring the reliability and durability of PV modules for 25+ years. To reduce cost, backsheets with a variety of compositions and constructions have been developed and introduced in PV modules. For PV module manufacturers, a major challenge is choosing a low-cost backsheet that can maintain the current levels of high reliability and durability performance. In the work reported in this paper, the properties of several backsheets of various compositions and constructions were compared.

This paper demonstrates that the future of the lowest-cost electricity generation from PV is not all about increasing cell and module efficiencies and minimizing cost/Wp, but rather squeezing the best out of a system using a few simple tricks, such as bifaciality, tracking and ground reflection improvements, to achieve the lowest cost/kWh.

A critical failure mechanism for PV modules is the degradation in performance as a result of exposure to temperature and humidity. In the case of flexible PV modules, moisture-induced damage becomes a greater concern, since the moisture resistance of barriers and polymer packaging is expected to be lower than that for conventional glass–glass PV products. The work presented here is aimed at establishing, through the use of accelerated testing, the field lifetime of flexible PV modules with regard to moisture-induced degradation.

Silicon heterojunction solar cells demonstrate key advantages of high conversion efficiency, maximum field performance and simplicity of processing. The dedicated materials, processes and technologies used for the metallization and interconnection of this type of cell are reviewed in this paper.

This paper summarizes the status and potential of screen-printing technology, and describes the results and thoughts of ISC Konstanz relating to the present and future of metallization technology.

Passivated emitter and rear cell (PERC) technology has been forecast to become mainstream in the next few years, gaining around a 30% market share. This paper presents a novel PERC solar cell design in which a screen-printed rear aluminium (Al) finger grid is used instead of the conventional full-area Al rear layer, while implementing the same PERC manufacturing sequence. This novel cell concept, called ‘PERC+’, offers several advantages over PERC, explored in the paper.