Tracking PV modules towards the sun offers gain in yield of 15% to over 35% relative to fixed mounted PV installations. To reduce material costs and to offering the double use of land, the Solar Wings tracking system was developed using cables to serve as mounting platform and to use cables to move the module toward the suns position. Up to know a prototype of a one-axis System was installed in Dec 2009 and the prototype of the twoaxis system started operation in 2010. The excellent track record of the one-axis Solar Wings installation is proofen by a overall system performance ratio of 92.3% in the complete first year of operation and 91.7% since the beginning of 2010 till this date of report in August 2010. Without any interruption of operation the annual yield of 1308 kWh/kW could be reached for that site in southern Germany. The gain of 23% due to one-axis Solar Wings tracking was measured by comparison the yearly the readings of a tracked irradiance sensor and a fixed mounted sensor run by the Fraunhofer ISE lab. In 2010 a two axis Solar Wings tracking system was installed and also operates without any shot down. In 2011 a one-axis Solar Wings tracking system will be installed on top of a small ski-lift in Switzerland.

The Solar Wings Tracking system is a new light-weight cable-based tracking system, offering several advantages, including double use of land, far lower demand for raw material, simple implementation of tracking motion and inherent mechanical robustness. A first 650 kWp PV plant based on a one-axis Solar Wings tracking system has been built and put into operation in Southern Germany in December 2008. The performance of the solar park has been monitored since and successful tracking operation with excellent performance ratios of the hardware applied has been confirmed. An AC yield of 1038kWh/Wp was measured in the period from January to August 2009 resulting in an about 20% higher energy yield than a fixed installation. Furthermore, a two axis system based on the Solar Wings concept has been designed and will be implemented in November 2009. Moreover, results of tracking combined with low optical concentration based on the Solar Wings concept has been demonstrated with a measured increase of 60% of solar power in the PV module plane, on a small scale design. In summary, successful implementation of a light weight cable-based light tracking system, offering double use of land, less raw material and further benefits has been confirmed, opening up new perspectives towards large scale application and the implementation of new concepts for increased energy yield of solar parks.

UNAXIS KAI PECVD reactors developed for AM LCD technology have been demonstrated to possess a high potential for thin film silicon solar cells based on amorphous and microcrystalline silicon. For the next generation of thin film modules with highly effective light-trapping LP-CVD ZnO large-area deposition is developed at Unaxis as well, in combination with a very simple but effective back reflector concept. A first prototype module of 0.447 m(2) active area with 7.1 % initial efficiency has been achieved for amorphous silicon. Micromorph mini-modules were prepared with 9.3 % initial aperture efficiency. All important module fabrication steps are under development at Unaxis for a complete line concept.

For optimizing solar cells, spectral response (SR) measurements are needed. An SR measurement system was developed for single and tandem cells with focus to silicon thin film devices. The system was designed to work in the industrial Unaxis R&D laboratory to develop modules for mass production. The task of the technical characteristics is a quick measurement and reproducibility better than 1% (68% confidence level). The software tool was developed to the needs of an industrial R&D lab. Keywords: Spectral Response, thin film cells

In this work, a new type of short water vapor treatment of the interface between the p- and i-layer is presented. This novel treatment is performed under vacuum below 1 mbar for 5 min and considerably reduces the i-layer boron contamination in amorphous silicon (a-Si:H) p-i-n solar cells prepared in single-chamber reactors. A significant advantage is that the substrate with the p-layer can remain loaded in the reactor during this oxidation treatment. The high effectiveness of this treatment in reducing the boron cross-contamination is directly supported by secondary ion mass spectroscopy measurements, by tracing the boron concentration depth profile across the p–i interface and by quantum efficiency measurements of the deposited cells. By applying this water vapor treatment, 0.3-μm-thick a-Si:H p-i-n solar cells of 1 cm2 with high initial conversion efficiencies of 10.1% are deposited in a commercial large-area (35×45 cm2) single-chamber PECVD KAI™ reactor and can clearly compete with cells deposited in multi-chamber systems. Light soaking of these cells for 1200 h at 50 °C leads to stabilized efficiencies of 8.2%. The relative typical efficiency degradation of 20% of such 0.3-μm-thick single-junction cells demonstrates that this treatment does not affect the stability in a negative manner.

UNAXIS KAI PECVD reactors developed for AM LCD technology have been demonstrated to process a high potential for manufacturing of thin film silicon solar cells based on amorphous and microcrystalline silicon. The single-chamber KAI reactors could fabricate already cells and modules. First microcrystalline silicon and micromorph tandem test cells of 5.5 % respectively 9.16 % were obtained. Up-scaling to sub-modules (491.5 cm2) by laser patterning resulted in initial aperture efficiencies of 8.8 % for a-Si:H p-i-n cells. A first prototype module of 0.447 m2 active area with 7.1 % initial efficiency has been achieved for amorphous silicon. Up-scaling of LP-CVD ZnO to areas of 1.4 m2 is ongoing for the next generation of a-Si:H and µc-Si:H based solar cell modules.

A study of the i-layer porosity as a function of the deposition parameters by PECVD technique, is presented here. It is demonstrated in particular, that for a fixed deposition rate of 2 Angstrom/s, increasing the plasma power tends to increase the layer density, while increasing the pressure tends to increase the layer porosity. Regarding the cells, no correlation between the layer density and the initial cell performances is observed. On the contrary, the i-layer porosity seems to influence the cell degradation: High porosity of the i-layer leads to high degradation, which gives an easy tool to investigate the layer quality. (C) 2003 Elsevier B.V. All rights reserved.

Note: IMT-NE Number: 398 Reference PV-LAB-CONF-2004-009 Record created on 2009-02-10, modified on 2017-05-10

Note: IMT-NE Number: 399 Reference PV-LAB-CONF-2004-008 Record created on 2009-02-10, modified on 2017-05-10