Dark current in a solar cell is a reverse bias leakage current that happens without light. It comes from the thermal creation of electron-hole pairs at the p-n junction's depletion region.
Dark current directly affects how well solar cells work. It drops the open-circuit voltage, thus lowering the solar cell's maximum power output. It also affects the fill factor. This factor shows how well the solar cell materials work together. Fenice Energy's goal is to reduce dark current effects.
If dark currents are high, fill factors are low. And when fill factors drop, so does the cell's efficiency at turning sunlight into electricity. The effect of temperature on dark current is also crucial. As temperatures rise, so does the dark current.
The short circuit current (Isc) increases with temperature, since the bandgap energy (Eg) decreases and more photons have enough energy to create e-h pairs. However, this is a small effect. For silicon The main effect of increasing temperature for silicon solar cells is a reduction in Voc, the fill factor and hence the cell output.
Experimental research performed by inducing typical defects showed that, the existence of defects of any type and anywhere in the solar cell will surely play a degrading factor and influence its dark current voltage (I-V) characteristic .
Dark current-voltage (I-V) response determines electrical performance of the solar cell by providing reliable and accurate information regarding its series and shunt resistances, diode factor, and diode saturation currents; the diode parameters determine the quality of metallization and solar cell efficiency.
How does reverse current affect a solar module surface temperature?
Maximum module surface temperatures were directly related to each value of the induced reverse current and in to the amount of current leakage respectively. Microscopic changes as a result of hot spots defects and overheating of the solar module, linked to reverse current effects, were also documented and discussed.