Photovoltaics International Papers

The passivated emitter and rear contact (PERC) cell design is gaining acceptance in solar cell manufacturing because of its potential for high efficiency with p-type wafers and its easy integration into existing production lines. In terms of PERC mass production, an effective and reliable AlOx deposition tool is the most important aspect that needs to be considered. Light-induced degradation (LID) is a cell efficiency bottleneck because of bulk recombination, even if the silicon surface is well passivated. This paper examines the combination of cell efficiency, AlOx tool choice and LID regeneration as a route to industrializing PERC technology

The mechanical strength of monocrystalline and multicrystalline silicon wafers is mainly dictated by the cracks induced during the wire-sawing process. Different sawing technologies, such as diamond-wire- or slurry-based processes, lead to different strength behaviours of as-cut wafers. Furthermore, the strength is strongly influenced by texturization, and at this stage can be interpreted as the basic strength of a solar cell. The metallization and firing processes determine the final strength and reliability of a solar cell, with the metallization contacts being the root cause of breakage of solar cells, depending on the particular cell concept. This paper gives a comprehensive overview of the typical ranges of strength for as-cut wafers, textured wafers and solar cells, for the two different sawing technologies. Around 100 batches with 4,253 samples were evaluated in the study.

As other entrants in the solar industry scramble to build greater efficiencies into their supply chain, the leading companies focus on manufacturing strengths such as zero-defect quality along the entire supply chain. When it comes to supply chain excellence, the solar industry as a whole is playing catch-up. However, there are players who have already made substantial progress here, having already adopted ‘lean’ practices to eliminate inefficiencies at source. REC, the largest European brand of solar panels and a world leader in the industry, is maintaining its strong position. The company’s practices and principles are explained in detail in this paper.

In this quarterly report we will provide full first-half 2015 analysis that shows a massive shift in the geographical location of planned production plants, as well as details on key capacity announcements in the months of May and June. The analysis of April’s capacity announcements were reported in the previous quarterly report. Despite April announcements being so low, May proved to be a blockbuster month. The return of meaningful solar cell capacity plans reiterates the strength in the recovery and the first attempts for many years by leading PV manufacturers to rebalance cell and module production as next- generation PERC technology leads the cell rebalancing act.

R&D expenditure by major PV module manufacturers showed a remarkable turnaround in 2014. Previous reports had noted, especially in 2013, that R&D spending had not been immune to the PV industry’s period of profitless prosperity and was deemed a discretionary spend by the majority of leading producers. A return to profitability for many in 2014 resulted in a year of new record spending. There was record spending from 11 of the 12 companies covered, with Hanwha Q CELLS' spending actually declining in 2014.

In this first quarterly report of 2015 a full first-quarter analysis will be presented, as well as the planned capacity announcements for March and April. Notably this will include Tier 1 manufacturers’ plans and a special lookat Malaysia and its potential for another wave of companies planning manufacturing operations in the country.Finally, further analysis of the potential renaissance in thin-film production will be provided.

As the upstream PV industry enters a new phase of growth, manufacturers are seeking new strategies and technologies to enable them to continue to cut costs and remain competitive. The sixth edition of the annual International Technology Roadmap for Photovoltaic describes the key trends likely to shape the PV sector in the coming year. This paper analyses some of the most promising areas for development.

Poor insulation resistance in modules is one of the primary contributors to module failure. Regimes currently in place to test the insulation resistance of crystalline silicon modules have proved problematic, as the conditions found in a laboratory are not on a par with environmental conditions at installation sites. This paper explores the shortcomings of current testing standards and recommends further tests that should be introduced to prevent module failures in the field.

High-efficiency (HE) PV technologies, such as heterojunction, back-contact or n-type, can be affected by significant measurement errors compared with conventional technologies; the power measurement of HE crystalline silicon PV modules and cells has therefore been a challenge for the PV industry for at least two decades. To deal with the internal capacitance and the spectral mismatch errors of HE cells and modules, various measurement techniques are currently used: steady-state, multi-flash, dynamic I–V, DragonBack™ and dark I–V and reconstruction methods, to name a few. This paper discusses the challenges and provides guidance for best practice for acquiring accurate measurements.

Potential-induced degradation (PID) of the shunting type (PID-s) is one of the most severe forms of PID, which is caused by the negative potential of p-type solar cells with respect to grounded frames/mounting. Although this negative potential can be completely avoided at the system level, that is not the case for a large number of modern PV systems. PV modules that are able to sustain PID-s stress for at least the duration of their service life are therefore essential. To assess whether modules fulfil this requirement, laboratory tests are currently recommended in which the modules are exposed to a certain constant level of PID-s stress for a given amount of time. These types of test with constant stress levels, however, are only feasible in the case of degradation mechanisms that are not reversible in the field, for which non-coherent stress episodes simply sum up to the total stress. Unlike other mechanisms, PID-s is reversible under field conditions; as a consequence, the level of PID-s of a fielded module is the result of an intricate interplay of phases of degradation and regeneration. This behaviour cannot be replicated in a laboratory test using a constant stress level; the currently recommended laboratory tests for PID-s with constant stress levels are therefore not appropriate for assessing the service life duration, and can only be used for differentiating the susceptibility to PID-s stress and for monitoring the stability of production processes. For monitoring the PID-s resistance of its products, Hanwha Q CELLS uses tests for PID-s with constant stress in accordance with the draft for IEC PID test method 62804. This assures that all the products of the Q CELLS brand come with Anti-PID Technology (APT). The expected service life duration with respect to PID-s is assessed by simulating the interplay of degradation and regeneration under non-constant outdoor conditions that are based on meteorological data.