https://nuigalway.ie/power_electronics/documents/renewable_energy_2010.pdf

A new methodology to optimise solar energy extraction under cloudy conditions

Abstract The performance of GaAs solar cells has been calculated as a function of the doping levels, using practical values for the transport parameters. Calculations show that surface recombination is a more probable cause than recombination in the junction region of the poor efficiencies obtained in practice. Electric fields built into the cell by doping gradations may be used to reduce surface losses and produce an efficiency exceeding 20 per cent for a surface recombination velocity of 10 6 cm/sec. This figure allows for the finite resistance of the surface layer, the effect of which is considered in detail for several cases. Results for Si cells are also presented. These are well in accord with the values obtained in practice. For both materials consideration is given to the degradation brought about by particle bombardment.

Calculated efficiencies of practical GaAs and Si solar cells including the effect of built-in electric fields. Technical report

We present a design method for metallization patterns that gives an optimal metallization pattern without any pre-assumptions on the topology of the pattern. The method can be used to optimize for both maximum eAciency at a particular irradiation condition and maximum yearly yield. PRINCIPLE OF THE DESIGN METHOD Figures 1 and 2 illustrate the principle of the method with the help of a few fingers of an H-grid pattern. For the sake of argument, we assume it would be possible to smear out the metallization. The smeared out metallization covers the whole cell. The more darkly coloured cross-sectional area in Figure 1 remains the same so the conductivity of the metallization remains the same. In order to maintain the right overall transparency we assign to the full metallization in this case a uniform transparency of 75% because the finger spacing is four times the finger width. In the case of Figure 2 the transparency assigned to the smeared out metallization decreases linearly from 100% at the tip of the fingers to 50% at the intersection with the busbars where the finger spacing is twice the finger width. The smeared out metallization diAers from the fingers in one important aspect however: the fingers can conduct current only in the direction

A. Flat

Papers

Optimization of multi-layer front-contact grid patterns for solar cells