In what factors the open circuit voltage of photovoltaic depends? How the open circuit voltage of a photovaltaic device changes with intensity of incident light?
Open circuit voltage is the maximum voltage that the PV can produced. The power of PV is Voc multiple Isc . Current is constant until it reaches the maximum voltage. It not like battery of cells when you short it will produce infinity current but in PV it constant because the power is depended on light intensity
Hi,
the open-circuit voltage is connected to the intensity of incident light via one representation of the ideality factor:
n = q/kT * d V_oc / d ln (phi)
where q is the elementary charge, k Boltzmann's constant, T the absolute temperature and phi the light intensity. Normally, n ranges between 1 and 2. The magnitude of n tells you something about the dominant recombination mechanism. For n = 1, the recombination is mainly related to band-band transistions. Whereas, n = 2 points to recombination via trap states within the band gap (e.g., Shockley-Read-Hall recombination).
Note that there are different methods to estimate the idealiy factor, which can lead to contradictory results. The method described above is only one possible way to estimate the ideality factor.
Some further reading on that topic:
http://pubs.acs.org/doi/abs/10.1021/jz4012146
A perhaps simpler way to see it: A solar cell is a diode, and the IV-curve shifts downward linearly with the illumination. Isc is thus proportional to the illumination, while Voc changes logarithmically.
The PV panels are made up of semi-conductors, as more intensity of incident light is not able to get converted into electricity, ultimately results into heat generation which increases temperature PV panel.
The property of semi-conductors is such that increase in temperature decreases the open circuit voltage.
The main problem is in the semiconductor because increase in temperature decreases the band gap of a semiconductor the distance between valence band and conduction band decreases. So, there is increase in the flow of electrons as they require lower energy to break the bond
http://pveducation.org/pvcdrom/solar-cell-operation/effect-of-temperature
You can read our paper at:
https://www.researchgate.net/publication/258914568_PHOTOVOLTAIC_MAXIMUM_POWER_POINT_TRACKING_USING_SEPIC_CONVERTER?ev=prf_pub
Article PHOTOVOLTAIC MAXIMUM POWER POINT TRACKING USING SEPIC CONVERTER
A very good discussion on effect of Solar light intensity on open circuit voltage of solar cells. Even though its an old post, I am adding some recent findings in this topic and raising one question how can we understand difference between open circuit voltage and nanoscale open circuit voltage ?
I am attaching few articles.
As a basic questions on solar cells i would like to give an answer.
It is so that the short circuit current of a single junction cell is proportional to the incident radiation intensity G such that Isc ~ G. Then Isc=k G
The open circuit voltage depends logarithmically on the short circuit current Isc such that
Voc= nVt ln kG/ Is
with N the ideality factor,
Vt the thermal voltage,
K is the proportionality consatnt between Isc and G
Is is the reverse saturation current.
This equation follows from the one diode model of the solar cell.
For more information please follow the chapter in the link: Chapter Solar cells and arrays: Principles, analysis and design
Best wishes
A photo diode can do This. First we have to calibrate the system with the used load line. Second we start to take voltage measurement. The photo diode current can be in to BJT. The BJT is used as a current to voltage converter. This way we can relate intensity to voltage reading.
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