Your daily dose of photovoltaic technology developments and solar news

Outside of the challenges of fabricating state-of-the-art photovoltaic devices, further care must be taken to package them such that they can withstand environmental conditions for an accepted lifetime of 20-plus years. Moisture ingress is a big adversary to hermetic packaging. The diffusion of water through barriers and edge seals can be minimized by careful choice of materials and package/barrier architecture. However, at present, there exist no solutions for extremely water-sensitive materials for flexible applications. Presented in the following is a review of the physics of permeation, the means of measuring permeation, current architectural strategies for semi-hermetic packages, and a brief evaluation of some common encapsulant materials.

Armed with the aim of generating a knowledge base on CPV technology, ISFOC has installed 1.4MW of CPV and is executing up to a total of 3MW of power plants incorporating seven different technologies, all scheduled for completion in 2009. These pilot plants are being established to assist the industry in the setting up of pilot production lines and to obtain very valuable information such as reliability, suitability and production [1]. Rating measurement approaches have been proposed by ISFOC, but there remains a need for an international standard that is accepted by the CPV community. This paper presents ISFOC's proposed standards set and outlines the methodology adopted by the company in this respect.

Power quality and reliability are two very important factors in electrical power supply, particularly for specific branches of industry. Multifunctional PV battery systems can improve power quality, substitute uninterruptible power supply systems, and can offer additional services such as energy management and peak shaving. This article presents the results of an analysis of possible services under current German conditions and the measurement results of laboratory tests and a pilot demonstration.

The encapsulation of solar cells is one of the most enduring ‘traditional' process steps in the fabrication of a photovoltaic module. The need to protect the delicate semiconductor active solar cell with protective material to ensure long-term operation remains a critical step in the module assembly process. However, continued development of the lamination process and materials used for encapsulation are required to meet increased demands of 25-year guaranteed module operation in the field, shorter cycle-times and lower production costs. In this two-part article, we look at the challenges these and other factors are having on the lamination process, the equipment required and the developments taking place to meet module manufacturers' requirements now and in the future.

SolarWorld USA's two main manufacturing facilities in Camarillo, CA, and Hillsboro, OR, represent the past, present, and future of crystalline-silicon solar photovoltaic manufacturing in the United States. The Southern California site, which sits in a small industrial park across from a verdant expanse of strawberry fields, was home to one of the world's first (and at one time the largest) solar factories in the late 1970s, a historic campus that has changed corporate hands several times, from Arco Solar to Siemens Solar (1990) to Shell Solar (2001) and finally to SolarWorld (2006) over the three decades since its inception. This paper provides a look inside the factory doors.

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.

Among the various thin-film solar module options available, CIGS is especially interesting as it exhibits the highest efficiency potential. These chalcopyrite-based solar cells are manufactured on glass or flexible substrates using various thin-film coating methods for each layer. The central CIGS absorber layer is deposited by co-evaporation, selenization of elemental layers, and other methods. In order to achieve highest quality and reproducibility, the absorber properties must be properly monitored and characterized. In this contribution we shed some light on the most important analysis methods used for CIGS solar cell research, development, and production such as x-ray fluorescence, surface analysis, and Raman spectroscopy.

Lowering the cost of production of solar cells requires higher throughputs and higher production yields for thinner and more fragile silicon wafers, and inline processing could hold the key. However, current processes used in production do not enable full inline processing and often require a substantial amount of handling between process stations as the throughputs per station and tray requirements differ greatly. It will take many years before a full inline process flow is available and if it comes, wafers will most likely be positioned on a single tray throughout all process stations. This paper will discuss the current processing methods for all individual process steps and will provide an outlook on inline processing in view of the three cost reduction strategies: thinner wafers, higher throughput, and higher efficiency cell designs.

This paper presents a strategy for improving c-Si factory productivity and efficiency via software, focusing on software systems that improve yield and reduce cost. Specifically, the role of automation software systems and example areas where they can provide impact will be discussed. Key requirements of these software systems will then be identified that guarantee reusability, reconfigurability and extensibility, and thus high and continuing ROI. Case studies will then be presented illustrating how Advanced Process Control (APC) software has been successfully applied in the semiconductor and FPD industries to improve productivity and efficiency. The paper concludes with a roadmap for automation software implementation to support PV factory productivity and efficiency improvements.

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.