Dear Amr,

Dear colleagues

There exist a very practical method to determine the shunt and the series resistance by first plotting the the dark I-V characteristic. in this case you can interpolate the the characteristics near zero voltage   where the the I-V characteristics will be a clear straight line. You can get the best fir straight line, where its inverse slope will be the shunt resistance.

Then we plot the I-V characteristics in a semi log scale, it will be a straight line in the middle current range where the current is dominated by the exponential dependence.

The semilog I-V characteristics deviates from the straight line at high currents. The deviation of the voltage dV at certain current is due to the voltage drop on the series resistance IRs. So, Rs = dV/ I.

To see this tecniques applied for extracting the solar cell parameters please follow the link:https://www.researchgate.net/publication/3062547_A_distributed_SPICE-model_of_a_solar_cell

Article A distributed SPICE-model of a solar cell

you can find very useful information regarding modelling of PV cell in the following link.. hope this will help you...

http://ecee.colorado.edu/~ecen2060/materials/simulink/PV/PV_module_model.pdf

Bare in mind that both these parameters may be dependent on the operating point you are considering. However, as a rough guide, the series resistance is the slope of the IV curve at zero voltage and the shunt resistance is the slope of the IV curve at zero current.

Mojtaba,

You can determine the series resistance by calculating the inverse of the slope of the I-V curve at the open circuit voltage and you can determine the shunt resistance from the inverse of the slope of the I-V curve at the short circuit condition V=0.

If you are interested in the other parameters of one diode model you can use the curve fitting methods to determine them. The one diode model parameters are IS, the reverse saturation current, the ideality factor n, the series resistance RS and the shunt resistance RSH  in addition to the photocurrent IPH.

I think that calculating the solar cell  resistances by slope method may cause big errors especially when comparing the performance of many solar cells of close J-V curves.

So, is there is any other accurate method to get Rs and Rsh?

Dear Amr,

Dear colleagues

There exist a very practical method to determine the shunt and the series resistance by first plotting the the dark I-V characteristic. in this case you can interpolate the the characteristics near zero voltage   where the the I-V characteristics will be a clear straight line. You can get the best fir straight line, where its inverse slope will be the shunt resistance.

Then we plot the I-V characteristics in a semi log scale, it will be a straight line in the middle current range where the current is dominated by the exponential dependence.

The semilog I-V characteristics deviates from the straight line at high currents. The deviation of the voltage dV at certain current is due to the voltage drop on the series resistance IRs. So, Rs = dV/ I.

To see this tecniques applied for extracting the solar cell parameters please follow the link:https://www.researchgate.net/publication/3062547_A_distributed_SPICE-model_of_a_solar_cell

Article A distributed SPICE-model of a solar cell

Thank you Dear Abdelhalim.

 I will go with the answer given by Zekry sir thank you sir

On the one hand it is nice to extract shunt and series resistance just from the dark current--voltage characteristic, because in that way one can be sure to obtain the intrinsic material-related response of the device under test, without being influenced by "special effects" possibly occurring under illumination. For example, a small fraction of a large-area cell might have a strong series resistance problem. Under illumination this gives rise to an I--V curve looking like that of a shunted cell, cf. Bowden & Rohatgi (2001), https://www.researchgate.net/publication/27541224 (see also http://www.pveducation.org/pvcdrom/characterisation/series-resistance-measurements for other "special effects").

On the other hand this means that if the device under test indeed shows "special effects" at certain operating conditions, the values obtained in the dark might not be fully relevant for the device operation under illumination. And especially novel types of solar cells are good "special effects" candidates.

Therefore I recommend to test the series resistance value obtained from the measurement in the dark by checking it with the help of several current--voltage characteristics measured under different illumination intensities in order to find out whether the superposition principle holds for the device under test. The basics for this check are explained in detail by Wolf & Rauschenbach in their famous 1963 paper "Series Resistance Effects on Solar Cell Measurements" in Section 5 (see especially Fig. 7), a full-text PDF file is available here: http://www.sintoninstruments.com/PDFs/wolf-aec61-seriesresitance-searchable.PDF (unfortunately not under https://www.researchgate.net/publication/223585317).

Article Rapid and Accurate Determination of Series Resistance and Fi...

Article Series resistance effects on solar cell measurements

The easiest way to get a series and shunt resistance from your solar cells is used I-V software calculator. Here one of the online version (http://opvap.com/jsc.php). You just input the raw data of your I-V or J-V curve in that website and obtain several SC parameters including Rs and Rsh. 

Gud luck!

Be aware that in the OPVAP manual it says that "efficiency = FF * Voc * Jsc", which is just nonsense. For the proper definition, see http://www.pveducation.org/pvcdrom/solar-cell-efficiency.

Thank you Dr. martin for your information. 

I think we can just obtain parameters such Voc, Jsc/Isc and FF from that OPVAP and calculate the efficiency in that pveducation web.

I still don't understand how you "calculate" the efficiency, because it is defined as electrical output power divided by optical input power, and as far as I know, both need to be measured -- which is usually done in a flasher / solar simulator having a more or less suitable light spectrum. To obtain a calibrated value for the efficiency, a reference cell has to be measured in parallel, the temperature has to be well controlled etc. How would you replace all this by a calculation?

Yes Dr Martin I agree with you in order to get more accurate value for PCE of SC, we need to measured the references cells. In my case, J-V measurements were performed using a Keithley 2401 source unit under the light intensity AM 1.5 G (100 mWcm-2) illumination (Newport). The spectral mismatch was calibrated using a KG-5 filter-covered mono-silicon detector. In the software (from Newport company) we can obtain the PCE, and others SC parameters values Including sheet and shunt resistance directly. The input power for efficiency calculations is 1 kW/m2 or 100 mW/cm2, thus if we know our active area of SC covered by metal electrode (measured by metal mask to give more accurate value), we can get Pin in W unit. In some my friends lab. I know the software only give J-V (I-V) curve only. So by using software, one of online version software that I know is OPVAP or PVeducation website.

Best!

Dear Mojtaba ,

You can calculate Rs and Rsh from the dark I-V by ploting differential resistance vs voltage.

It is clearly explained in the paper attached below.

I tried the method presented by Prof. Mojaba, and it's correct.If forward scanning, the value of Jsc is negative after origin, then you should take note to multiply (-1) as no sense for Log (negative value).

Single diode with Rs and Rp are not sufficient to model of all types of PV. For example, You need two different diodes for a-Si model.

to introduce the effect of surface recombination velocity , interface statement is used how to choose the value of x.min x.max y.min y.max

witch region?

Much helpful info from Abdelhalim Zekry .