Solar cell emitter design with PV-tailored implantation

A potentially cost-effective ion implanter for solar cells has become commercially available very recently. As the emitter dopant profiles differ from the standard diffusions, a combination of process simulation and device simulation is used to predict possible applications as front emitter. The simulations show that ion energies of 10 to 30 keV and doses in the range of 5×1014 to 7×1015 cm-2 are sufficient for reducing the phosphorus peak density and, hence, obtaining cell efficiency levels above 20%, if appropriate surface passivation and wafer materials are used. The simulations strongly indicate, however, that cell efficiency improves only marginally if the cell has a fully metallized rear Al-BSF and a boron-doped Cz base in the degraded state. Simulated cells with a local rear Al-BSF show an efficiency improvement of more than 0.3% absolute in the degraded state

Numerical simulation of tunnel diodes and multi-junction solar cells

In order to connect individual subcells in monolithically grown multi-junction solar cells Esaki interband tunnel diodes are widely used. In this work, numerical simulations of an isolated III-V Esaki tunnel diode and of a dual-junction solar cell are presented. With a tunnel model, which takes into account the full nonlocality of the tunneling process, a good agreement between measured and simulated IV curve of a GaAs tunnel diode could be achieved. Using this model, the EQE and the IV curve of a complete dual-junction solar cell including tunnel diode was simulated. The model is applied to calculate the current-matching condition of the dual-junction cell

Numerical simulation and modeling of III-V multi-junction solar cells

This paper presents results of numerical simulations of a III-V dual-junction solar cell including tunnel diode and Bragg reflector. The simulations are carried out in a commercially available semiconductor simulation environment. For the computation of the quantum efficiency of the subcells a special procedure using biasillumination and bias-voltage is implemented. The model is validated by a comparison of simulated external quantum efficiency (EQE) and IV curve with experimental data. A very good agreement is achieved. Simulations are used to illustrate the influence of the Bragg reflector and the tunnel diode on the EQE. Additionally, the capabilities of the model for design optimization are exemplified by an adaption of the subcells' thicknesses

Concentrator array based on GaAs cells and Fresnel lens concentrator

A high-efficiency concentrator PV array with an aperture area of approximately 1 m"2 and a geometrical concentration ratio of 120 x was fabricated. An all-glass design was chosen because of big advantages for many reasons. Glass was used as a superstrate for the concentrating lenses and as backside and sidewalls of the module-housing. Additionally, a very short focal length of 75 mm made the modules extremely compact. In this paper the manufacturing of the module is described and first results are presented. Long-term outdoor tests are foreseen. (orig.)Available from: http://www.ise.fhg.de / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman