Your daily dose of photovoltaic technology developments and solar news

The main goal of the solar industry is to reach grid parity as soon as possible. This can be achieved by reducing the manufacturing costs, by increasing conversion efficiencies and/or by improving the lifetime of solar modules. Driving down the cost of modules is not straightforward. Commercially available PV modules are typically sold with 20-year warranties, and changing these materials for economic reasons requires extensive material testing and recertification of the new module design. In the following sections, we will focus on the cost drivers of module manufacturing processes and how that could evolve into new module designs.

In today's market, crystalline silicon wafer technology dominates industrial solar cell production. Common devices feature opposing electrodes that are situated at the front and rear surface of the wafer and subsequent front-to-rear interconnection is used for module assembly. This paper reflects the functions which have to be fulfilled for the backside contact of the solar cell as well as challenges and advances for the two basic classes: full-area and local rear contact formation. While full-area contacting has proven to be a reliable technology for industrial production, local contacting through dielectric layers has yet to be put through its paces in industrial implementation.

Chemical stoichiometry along with depth profiling and metallic contamination is of considerable interest for photovoltaic thin films. Conversion efficiency can be affected for example if primary components, e.g. Cd and Te, are not present at proper ratios. Moreover, amorphous silicon can vary substantially between sources and deposition technique, and qualitative comparison of trace metallic contaminants may not be sufficient to ensure final thin-film quality. This discussion presents data from atomic emission and mass spectrometry techniques that quantitatively and accurately describe both bulk and trace elemental compositions in photovoltaic materials, various thin-film matrices, and the final thin-film cell and module.

The recent photovoltaic industry shakeout which started around Q3 2008 has faced the overcapacity, credit crunch, and economic crisis that significantly declined the average selling price by 50-65%, including the price of thin-film photovoltaic modules. The changing business environment has put significant pressure on all PV manufacturing technologies but more candidly on amorphous silicon thin-film single-junction module manufacturers to advance and scale up the device efficiency and aggressively drive cost reduction. This paper outlines the technical approach taken at Moser Baer Photovoltaic Technologies India Limited (PVTIL), including process optimization and device
management strategies, to enhance the efficiency (total area) of the thin-film single-junction amorphous silicon module as manufactured using Applied Materials' SunFab line.

PV manufacturers can quickly reduce their costs, and increase their yields, by using SEMI standards that were originally designed to help semiconductor fabs deal with power glitches and power costs. SEMI, the global industry association serving the manufacturing supply chains for the microelectronic, display and photovoltaic industries, has two well-established electric power standards that could prove especially useful for PV manufacturing: SEMI F47, which helps equipment deal with power disturbances, and SEMI E6, which helps users understand how much electric power is used in their recipes. This article provides a method of lowering costs and increasing yield by applying these standards in the PV manufacturing industry.

The PV industry is expected to eventually reduce its manufacturing costs well below €1/Wp. Major technological changes lie ahead of us for manufacturing wafers, solar cells and modules if this cost target is to be met. In order to focus R&D efforts amongst the myriad options, and to speed up the learning curve, the PV industry (equipment vendors, material suppliers and PV manufacturers) may benefit from collaborative efforts guided by an ITRS-like roadmap. In this paper we present the IMEC roadmap, the target of which is to reduce drastically the amount of pure Si needed per Wp by combining efficiencies beyond 20% with aggressive reductions in wafer thicknesses.

With growth in 2009 suffering from recession and an ongoing credit crunch, this paper presents a review of the key trends in cell and module manufacture for the crystalline silicon (c-Si) PV module market. The c-Si segment remains the largest segment, and is competing effectively with less mature thin-film technologies. PV is still a largely uneconomic way to generate power, and requires subsidy to maintain sales volume and growth. While subsidies exist, the industry treads the narrow path of growing at a healthy clip, developing robust technology and business models, and mapping paths to profitable business without subsidies once PV installations become economically viable.

The current feed-in tariff (FiT) scheme in Italy has so far resulted in a total installed PV capacity just above 760MWp (925MWp considering also the first FiT). The majority of those installations (71%) are building-adapted (BAPV) or buildingintegrated (BIPV) thanks to the higher incentives provided compared to non-integrated ground-mounted plants. Moreover, there are special premiums on top of the basic FiT, such as when asbestos roofings are replaced with PV modules. On the one hand, this makes the Italian PV market very attractive for those players specialized in roof applications, while on the other, it represents an opportunity and a strong motivation for both the installers and the manufacturers to explore innovative and standardized BIPV solutions and materials. Will this trend continue in the years to come?

Heat transfer and control of the temperature field are important in the production of silicon solar cell wafers. Present work focuses on the first steps of the production chain, i.e. crystallization and wafering. For the crystallization process, control of heat transfer is crucial for the ingot quality in terms of grain structure, impurity distribution, particle formation, and ingot stresses. Heat transfer is also important during subsequent processes, in particular the wire sawing of the silicon blocks into wafers. The paper emphasises the role of heat transfer and explains the consequences for these processes. Examples from experimental trials and measurements are combined with models and simulation methods.

As demand for solar products prompts producers to scale up their manufacturing operations, CH2M HILL's advanced technology manufacturing experts consider some of the most significant issues related to factory expansion. This article consists of the direct experiences these experts have gained from the scale-up activity in other industries with technological similarity to solar - most notably from the semiconductor and flat panel realms.