Photovoltaics International Papers

A recent spate of solar cell efficiency gains and record results underline the continued efforts to boost conversion efficiencies, which are at the core of reducing cost-per-watt goals. However, bringing such technology into the mainstream volume production world at little or no increase in manufacturing cost will prove more challenging. This paper takes a look at the current mainstream c-Si cell metallization efficiency developments that are starting to enter volume production with a promise of 20% cell efficiencies and low manufacturing costs.

Among all of the tests performed in the production chain of solar cells, each with the scope of production control and the aim of driving engineering improvements, the electrical final test is certainly the most important. The final test defines the gate to module manufacturing and has a direct impact on finances and customer satisfaction. The test procedure itself is well known and continues to undergo constant further development, but that shall not be the scope of this article. This paper will elucidate on the issues faced by bringing these tests into high volume production, highlighting some issues on measurement accuracy and degradation of the internal calibration standards. In addition to pure electrical testing, the paper will discuss the Q-Cells approach to identifying hot spots and subsequent binning of the affected cells without adding process time to the test procedure, and will show their straightforward correlation to heat generation of these hot spots in real-life condition-encapsulated module tests.

Thin-film module production has proven itself as a forerunner in the race to drive down costs for photovoltaics. The type of semiconductor material used is the most differentiating factor for thin-film photovoltaics, playing the decisive role for determining which core processes are employed and what type of equipment is used. This explains why discussions related to thin-film costs and technologies usually focus on the semiconductor type. However, the effects of glass production, processing and handling are often underestimated: factors such as scaling, yield, unit cost and total cost of ownership of the equipment are defined by the glass-production side of the industry. This paper discusses the challenges faced in glass washing and handling in thin-film PV production.

This paper describes the functionality, applicability, and the development of dependency maps which are the basis for standardized information exchange between responsible parties during the fab design process. Examples and experiences are related to the solar industry; however this generic approach may be applied to a wide range of different industry sectors with similar challenges. The aim is to provide a guideline for realizing a fab design of dynamic and complex production systems. Its main benefit is a higher degree of transparency regarding dependencies within the production system, which results in a reduction of risk for incorrect planning. In addition, it enables the factory designer to execute the fab planning process and further continuous improvements for achieving respective targets.

As polysilicon producers perform expansions and upgrades to increase production and improve operations, plant safety remains critical. Companies should routinely review their safety policies and effectively plan their projects to ensure uninterrupted product supply and create a safe environment for employees and the communities in which they operate. Both the design and the execution of expansion and upgrades to projects are critical as companies strive for minimal down time so that productivity is not affected. Such hazards and scenarios that may hinder and delay start-up, specifically in relation to polysilicon plants, are highlighted in this paper. Furthermore, the paper outlines how best to avoid these situations, offering methods of execution to achieve the three key measures of success: safety, high purity and minimal down time.

Multicrystalline wafers are the workhorse of the PV industry, with approximately 60% of crystalline silicon solar cells made from the substrate. They offer cost advantages in the form of good conversion efficiencies, which should continue to improve as cell technology advances continue. However, wafer prices were acutely impacted by the fall in PV market demand in late 2008, which continued through most of 2009. With relatively high capital costs, continued pricing pressures and calls for greater quality and control, wafer producers are now set on a course that requires rigorous and sustainable production cost-reduction strategies to meet customer requirements. This paper focuses on strategies that can be adopted to address this need for tighter quality specifications that reduce manufacturing costs downstream and boost cell conversion efficiencies.

Interconnection of inverters to the electrical grid is a key issue for the widespread integration of distributed energy resources, especially when the scenario surrounding international standards is so unclear. As a pre-normative research step, a round-robin test of two small-scale photovoltaic inverters was performed by nine DERlab laboratories during 2009. The test activity was focused on the verification of individual test procedures, common interpretation of standards and requirements, and determination of problems related to the equipment and facilities involved in conducting round-robin tests. Compilation of test results and first conclusions of this activity will be presented in this paper.

Development of fine-line crystalline silicon solar cells is a potential direction for application of high-efficiency and low-cost solar cells in the industry. Fine-line mask-free metallization offers a great potential to increase cell efficiency by reducing metal shadowing losses and surface recombination losses. At China Sunergy, three promising approaches for fine-line crystalline silicon solar cells are currently undergoing research, including processes such as laser doping selective emitter (LDSE) technology, inkjet or aerosol jet printing of metal paste and upgraded screen-printing technology. This paper presents the basic investigations of these three manufacturing technologies, singling out the technology that presents the most potential for further application.

The French Ministry for the Environment, Ecology, Sustainable Development and Sea (MEEDDM) officially published a new decree concerning photovoltaic electricity generation and feed-in tariffs (FiT) on January 12th 2010. This was followed by a second decree, published on March 16th 2010, which contained some additional information and revisions to the first. This paper outlines the effects the revisions will have on France’s solar industry and provides guidelines for future developments in the country.

Power measurements of PV reference modules can, at standard testing conditions (STC), show tolerance deviations of up to ±3%, greatly affecting the maximum power output and thereby lowering the overall energy yield of the installation. Despite some existing technical problems, there is an urgent need on the part of the photovoltaic community to achieve more accuracy in power measurements in respect to the ever-growing production volumes. Some approaches being undertaken to carry out high-quality power measurements are addressed in this paper. The deviation from an ideal simulator performance are shown and discussed for two types of simulators, with reference to the most relevant parameters: irradiance level, deviation from homogeneity, spectral mismatch and temporal stability.