Dark Current Solar Cell

Because solar cells transform light to electrical energy it might seem odd to meacertain the photovoltaic cells in the dark. However before, dark IV measurements are inuseful in researching the diode properties. Under illumination, little fluctuations in the light intensity include substantial quantities of noise to the system making it difficult to create. Dark IV dimensions usage inject carriers right into the circuit through electrical means quite than with light created carriers. In most cases the two are indistinguishable and the Dark IV measurements give added information around the cell for diagnostic objectives. Even in the absence of noise, tright here is a wealth of information in comparing the illuminated and also dark IV curves.

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A solar cell in the dark is a big level diode. A straightforward dark IV measurement produces the exponential curve so characteristic of adiode.


Dark IV curve with a linear range. One exponential looks a lot choose one more.

The linear graph of existing vs. voltage reveals exceptionally little bit indevelopment about the diode, much even more information is revealed from a semilog plot.

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Semilog plot of the same IV curve above revealing much more information around the diode. Different areas of the IV curve are conquered by different loss mechanisms.


Dark IV measurement of a PERL cell. While the cell had a document Voc of 702 mV the fill factor was just 0.81, reduced than the 0.83 for earlier cells. Additionally, tright here was no evidence of parasitic series or shunt resistance. The dark IV measurement proved an unusual curve wright here the J0 was transforming and was defined by a transforming recombination velocity at the rear surface 1.

Limitations of Dark IV Measurements

The usage of Dark IV curves in solar cell evaluation depends on the principle of superplace. That is, in the lack of resistive impacts, that the light IV curve is the dark IV curve shifted by the light produced present. While this is true for most cells it is not always the case.

A second difficulty is that in dark IV dimensions the current is flowing in the opposite direction and also the present paths are different. The change in the existing route reasons a lower series resistance in the dark measurements to the light measurements.

Comparison of existing courses under illumination and in the dark. In both situations the currental fees are the same. In the dark case the current flows right into the cell and in the illuminated case the existing flows out of the cell. Due to the fact that in the dark situation, a lot of of the current crosses the junction under the contact it has actually a reduced series resistance than for the illuminated case. (relocate the computer mouse over the photo to view dark current flows)

1. Introduction2. Properties of Sunlight3. Semiconductors & Junctions4. Solar Cell Operation5. Design of Silicon Cells6. Manufacturing Si Cells7. Modules and Arrays8. Characterization9. Material Properties10. Batteries11. Appendices