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The interconnection of solar cells by shingling increases the active cell area in photovoltaic modules. Cell-to-module (CTM) gains and losses change significantly. We present models to calculate these gains and losses for shingled cells. Module efficiency and power can be increased with the shingle interconnection technology by +33 Wp and + 1.86% abs in the analyzed design, when compared to common ribbon-based interconnection. The CTM-ratio for efficiency improves due to shingling and also the CTM-ratio for power increases compared to conventional modules with ribbon or wire cell interconnection.

Today's Photovoltaic module production is driven by cost. Due to its high conductivity and solderability the precious metal silver is used in standard solar cell production as base material for solder pads. The need for replacing the costly silver emerges in various PV metallization techniques On the rear side, these solder pads (busbars) locally prevent the formation of a back-surface-field (BSF) leading to a decrease in open-circuit voltage. We therefor aim at reducing the silver content in solar cells while maintaining the solderability. To face this challenge we developed an interconnection method based on ultra-sonic (US) soldering to contact the aluminum on standard crystalline silicon (c-Si) solar cells. The method consists of a two-step process where first a tin alloy is employed directly on the aluminum and second conventional interconnectors are soldered onto the applied tin alloy. We investigate the adhesion of five different metallization pastes on the solar cells and compare it to the adhesion of soldered interconnector ribbons with our two-step US-soldering method on these metallizations. We find the adhesion of the solder joints to be independent of the metallization/cell adhesion. Metallographic analyses reveal that the tin alloy forms a direct contact to the Al-Si-eutectic underneath the metallization during our US process. The measured adhesive forces range from 0.5 N/mm to 16 N/mm of the metallization/cell interface and from 1 N/mm to 2 N/mm for the US-solder joints. Additionally we manufactured a 16-cell module consisting of cells with US-soldered contacts on the Al-rear side and compare it to a conventional module. The IV-characteristics show less loss in FF from cell to module (CTM) for the US-soldered module.

Minimizing the optical and electrical losses from cell to module is essential for highly efficient PV modules. We use metal wrap through (MWT) solar cells with passivated rear surface to integrate them into a PV-module and minimize the cell to module losses. For this purpose, we analyze the optical properties of different encapsulation materials with respect to this specific cell type, i.e. the absorption losses in the encapsulants and coupling gains from refractive index. The best performing encapsulant shows a cell-to-module power loss of 0% for a 16-cell MWT module. The fill factor loss is 1.4% absolute. We reach a module efficiency of 17.4% on the aperture area implying a CTM-loss in efficiency of only 0.5% absolute.

International audience; Photovoltaic-thermal collectors (or PV-T collector) are hybrid collectors where PV modules are integrated as an absorber of a thermal collector in order to convert solar energy into electricity and usable heat at the same time. In most of the cases, the hybrid collectors are made by the superposition of a PV module on the thermal absorber of a solar collector. In this paper, the approach is different and is to analyze thermal and optical properties related to both PV and solar thermal functions in order to identify an optimum combination leading to a maximum overall efficiency. Indeed, although these two functions do not exploit the same range of radiation wavelengths, thermal and PV functions are not so complementary due to photo-conversion thermal dependency. In this context, an alternative PV cell lamination has been developed with increased optical and thermal performance. The improvements were evaluated around 2 mA/cm2 in terms of current density in comparison to a standard module encapsulation. Based on this technique, a real size PV-T module has been built and tested at Fraunhofer solar test facilities. The results show a global efficiency of the PV-T collector above 87% (79% thermal efficiency plus 8.7% electrical efficiency, based on the absorber area).

The power output and efficiency of a crystalline silicon PV module is a highly relevant quantity to evaluate novel cell, material and design technologies. It is therefore necessary to develop a full understanding of the different factors that impact the cell-to-module ratio. The purpose of this work is to demonstrate a unified methodology for predicting module power and efficiency from material and geometry data for several cell, interconnection and module designs. The methodology consists of analyzing photovoltaic inactive module areas, optical effects such as reflection, absorption and electrical losses. For a selection of efficiency impacting factors we show experimental results to demonstrate their influence on module efficiency and module power. The model has been validated by measurements on an H-patterned multi-crystalline 60-cell module showing a deviation in module power of only 1%, a value well within the flasher measurement uncertainty. For a 60-cell-module with pseudo-square monocrystalline solar cells with 19.9% efficiency we calculate absorption losses for different encapsulants in the range of 1.3 to 5.3 W. The power gain for the investigated backside materials is found to be in the range between 4.5 and 6.7 W.

Photovoltaic plays an important role in sustainable energy supply scenarios of the next decades. The photovoltaic industry has experienced strong growth in the 21st century and is expected to continue its progress (Figure 1). In 2009, waferbased module technology made up for more than 80 percent of the global PV market; the rest is shared among various thin film technologies. This article provides an overview of laser production technology used for wafer-based photovoltaic module production.

There are numerous possibilities for laser source manufacturers as well as laser equipment manufacturers in the photovoltaic market. On one side there are structuring steps unavoidable in thin film photovoltaic production, incorporating numerous small lasers per module production line. On the other there is a huge variety of possible laser processes in crystalline silicon photovoltaic, where it is only a matter of time until the first laser processes make their way into process sequences for higher efficient solar cells.

Windows represent a primary approach for direct indoor use of solar energy in terms of lighting and heating if differentiated radiation control ensures continuous visual and thermal comfort. Total internal reflection is a well known phenomenon that can fulfil directionally selective tasks covering most of the solar spectrum without absorption. Promising designs of dielectric structures are presented together with performance results from two-dimensional ray-tracing. Dynamic solar control systems based on rotatable slats can be modified in two ways. The first design complements state of the art prismatic structures in order to provide partial transparency of the material itself. A new approach rearranges the reflective segments in a way that enables total internal retro-reflection. The spacing between adjacent slats for unobstructed view can be increased for selected solar profile angles. For stationary solar control, cylindrical shells have been devised that can totally reflect a broad range of incoming rays. The new design removes the constraint on total reflectance aperture angle exhibited by prismatic geometry. Seasonal solar control on vertical southern facades can be achieved with a structure that reflects light only from high elevation angles and is partly transparent in other directions.

Crystalline silicon module technology aims to turn solar cells into safe and reliable products, while maximizing efficiency. The chapter highlights fundamental challenges comprising cell interconnection and cell encapsulation. Interconnection controls electrical losses from current collection and transfer, and impacts active conversion area as a side effect. Encapsulation is mainly responsible for overall optical performance, reliability, and safety. The chapter discusses efficiency loss and gain mechanisms from cell to module, typically totaling 10–15%. Module efficiency suffers from an increase in inactive area, from serial resistance losses, and from absorption losses. Gains from reduced reflection losses at interfaces often arise after encapsulation. Best results are obtained by carefully matching cell and module design. While the process steps of mainstream module manufacturing have hardly changed over the last decades, new materials have been introduced and full automation with comprehensive quality assurance is now widely adopted. The chapter closes with a presentation on alternative module concepts that hold promise to increase electrical and optical efficiency, and to reduce module manufacturing cost.

On the way to higher efficiencies, back contact solar cells seem to be a promising alternative to the conventional screen-printed solar cells. Especially, the metal wrap through (MWT) solar cell concept with only two additional process steps is appropriate for a fast transfer to industry. Hence, an industrially feasible process based on a new contact design was developed and tested at the pilot-line of the Photovoltaic Technology Evaluations Center (PV-TEC). A maximum cell efficiency of 16% is achieved. Compared with conventionally processed cells made of the same mc Si-block, an efficiency gain of 0.5% absolute is observed. Due to a cell interconnection on the back the serial resistance losses in the tabs decrease. Therefore, a fill factor of almost 77% and an efficiency of 15% for a MWT module prototype (16 MWT cells) is reached.

Wafer-based PV modules, which accounted for 87% of the market in 2010 [1] , include soldered cell strings. Yet, soldering is a critical process for the production yield because it introduces severe thermo-mechanical stress into the cell. The quality of solder joints will determine a module's reliability over its 20-25 years lifetime. The purpose of this work is to present a metallographic preparation method and the corresponding characterization of solder joints. These methods may be used for qualification of initial and aged joints thus providing an off-line quality control tool in the manufacturing of cell strings for PV modules. It is also an effective method in the development of new cell and module designs and in the evaluation of new materials.