Technical Papers

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

The photovoltaic market is currently experiencing a rapid decline in average selling price per module, resulting in a new era of challenges to reduce the investment and operational costs of manufacturing facilities. Subsequently, PV modules are rapidly gaining acceptance for industrial applications in the renewable energies sector. The PV industry will therefore need to progress toward high volume production of the established process technologies to meet future demand after the current inventory base has been installed. This paper addresses the potential impact of process technology, manufacturing and automation considerations, as well as the appropriate building concepts for large-scale crystalline silicon cell manufacturing. The other inherent advantages and considerations regarding fabs with a capacity approaching one gigawatt peak are also evaluated and discussed based on comparisons between two actual production facilities.

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.

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.

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.

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.

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.

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.

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.

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.