Spectral effects on amorphous silicon photovoltaic cells literature review: Difference between revisions

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Spectral effects on amorphous PV cells

--Effect of atmospheric parameters on the silicon solar cells performance, M. Chegaar, P. Mialhe Spectral effects simulated for Algeirs

effects in short-circuit current due to turbidity, decrease of: 4.41%, 4.7%, 7.34% for mono multi and amorphous. Turbidity decreases UV radiaiton

Increasing water vapour leads to decrease of 4.57%,4.4%, o.2% for same

Efficiency increase with air mass for crystalline, decrease for amorphous

-- [1. Rüther R, Kleiss G, Reiche K. Spectral effects on amorphous silicon solar module fill factors. Solar Energy Materials and Solar Cells 2002 Feb;71(3):375-385.]

amorphous silicon is more efficient in the summer

crystalline more efficient in winter

A:Si matches very well with indoor illumination spectra, they are more efficient indoors

Spectral mismatch factor: ratio between Isc rated and Isc extrapolated to 1000W/m2

Does not neccesarily hold true for a:Si cells: "However, in amorphous silicon solar cells, the proposition of the non-dependence of sðlÞ on the operating voltage does not hold. It is known that in p-i-n structures a typical blue-dispersion of the spectral response occurs for higher bias voltages [14]. Since the field-driven transport is the dominant mechanism with respect to diffusion, and since the electrical field is extended over practically the whole cell, the generation profile inside the cell produces a feedback on the internal quantum efficiency. In a-Si cell modelling, one takes advantage of this effect by application of the DICE method [12,15,16] to yield for a spatially resolved description of the field distribution inside the cell."

FF is the ratio between Imp and Isc

Used a filtered pyranometer to find "Red" and "Blue" spectra

Plots of FF vs Isc,shows much scatter in the central area of Isc.

Attrubited to the spectral effect, blue increasing FF, red to decrease it

Shows curves of spectral senstivity as a function of irradiation

--1. Rüther R, Livingstone J. Seasonal variations in amorphous silicon solar module outputs and thin film characteristics. Solar Energy Materials and Solar Cells 1995 Jan;36(1):29-43.

Outdoors testing of A:Si generally leads to better efficiency in summer, worse in winter

Attributed to thermal annealing and seasonal spectral variations

Conclusion of this paper is that spectral effects are dominating

first cells utilized indoors in calculators

power efficiency from 71% in winter to 83% in summer

bandgap from 360-780

Crystal silicon is better in the winter

therefore, the seasonal variatoin is likely due to the seasonal changes in spectrum, not annealing. Does not really support this with numbers

--R. Gottschalg, Experimental study of variations of the solar spectrum of relevance to thin film solar cells, Solar Energy Materials and Solar Cells. 79 (n.d.) 527-537.

useful fraction can very in the range of +6 to -9% from annual average

spectral mismatch factor: Fabero and Chenlo [7] and Merten [8] model the spectral mismatch with a spectral mismatch factor for the short circuit current of crystalline and amorphous silicon

Hirata and Tani [9], who used a pyranometer and 6 filters up to a maximum wavelength of 1200 nm and investigated the effect of the spectral changes on a-Si and c-Si devices.

Difficult to quantify the effects on multijunction units because it will cause a mismatch in the series connectes cells, leading to non-linear effects [13]

spectral effects though air mass and cloud cover(clearness index)

Annual fluctiations in useful fractions ~10%