How to calculate solar cell efficiency with data in dark?

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Discussion Overview

The discussion revolves around calculating solar cell efficiency using experimental data obtained in both light and dark conditions. Participants explore methods to derive efficiency metrics from dark data, including the challenges faced when applying the square method to IV curves that cross the origin.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes the difficulty in calculating efficiency in dark conditions using the square method due to the data crossing the origin.
  • Another participant suggests that there may be no concept of "efficiency in dark" and proposes that the behavior resembles that of a diode, with the ideality factor being a relevant measure.
  • A later reply indicates progress in deriving an exponential equation from the dark data, suggesting that the ideality factor (n) could be a solution to the problem.
  • One participant concludes that it is not possible to find efficiency using only dark data and emphasizes the need to combine this with short circuit current data under illumination to calculate maximum power.
  • Participants discuss the calculation of dark saturation current and its relevance to the ideality factor, with some expressing confusion about these terms.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of calculating efficiency from dark data alone. While some propose that the ideality factor is a relevant measure, others assert that combining dark data with illuminated data is necessary for efficiency calculations. The discussion remains unresolved regarding the exact methodology for calculating efficiency in dark conditions.

Contextual Notes

Participants highlight limitations in their approaches, including the dependence on specific definitions of efficiency and ideality factor, as well as the unresolved nature of certain mathematical steps in deriving the necessary equations from the data.

nbky
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Hi mates,
I have to find solar cell efficiency by datas that given. These datas comes from an experiment in light and in dark. I found efficiency in light by square method with IV curve.
But i don't know how to find in dark. The square method doesn't work cos data crossing the origin, no area to use this method.
I made some online research but haven't reached the right way.
Do you have any idea to calculate the efficiency?
 
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I haven't find the solution for 5 hours.now i think there is no "efficiency in dark". I guess it behaves like diode and the "efficiency" is ideality factor. do you agree with me?
If it is so i have new problem:

image013.png

here the equation: i have voltage and current in my data. others are constant. And what is dark saturation current, i don't get it?
 
it s me again.i made some progress.
As you know the data is exponential, starts from origin (ectually close to origin). if i get the exponential equation from graph (like y=a*e^b), i could find I0 and "n".
So the n is ideality factor of solar cell. So do you think is it the answer?
 
I did my work and sent. And i get the feedback and i just want to inform you just in case maybe someone else stuck same kind of problem.

First of all i learned it was a tricky question. You cannot find efficiency just using data in dark. You need to combaine that with at least short circuit current under illumination. Then you have a theoretical model for IV model that you can calculate max power.

with only dark data you can only calculate saturation current and ideality factor which the question ask for from the begining. You can find it from the graph like i just said in the last post.
 

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