# How to calculate solar cell efficiency with data in dark?

• nbky
In summary, the conversation is about finding the efficiency of solar cells using data from an experiment in both light and dark conditions. The speaker has successfully used the square method to find efficiency in light, but is unsure how to find efficiency in dark as the method does not work due to data crossing the origin. They have researched online but have not found a solution after 5 hours. The speaker suggests that the efficiency in dark may behave like a diode and proposes using the ideality factor to calculate it. Later, the speaker mentions making progress by using the exponential equation to find the ideality factor, which is then confirmed by feedback from their work. However, it is revealed that efficiency cannot be calculated solely using data from dark conditions and requires combining
nbky
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?

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:

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.

## 1. What is the formula for calculating solar cell efficiency in the dark?

The formula for calculating solar cell efficiency in the dark is: efficiency = (Pdark / Pmax) x 100%, where Pdark is the power output of the solar cell in the dark and Pmax is the maximum power output of the solar cell in optimal conditions.

## 2. How do I obtain the necessary data to calculate solar cell efficiency in the dark?

To calculate solar cell efficiency in the dark, you will need to measure the power output of the solar cell in the dark (Pdark) and the maximum power output of the solar cell in optimal conditions (Pmax). You can obtain these values by using a multimeter or other measuring device.

## 3. Can I use the same data to calculate solar cell efficiency in the dark as I would for calculating efficiency in optimal conditions?

No, the data used to calculate efficiency in the dark is different from the data used to calculate efficiency in optimal conditions. In addition to Pdark and Pmax, you will also need to know the area of the solar cell and the intensity of the light hitting the cell in order to accurately calculate efficiency in the dark.

## 4. Is it possible to have a higher efficiency in the dark compared to optimal conditions?

No, it is not possible for a solar cell to have a higher efficiency in the dark compared to optimal conditions. This is because the solar cell relies on light to generate electricity, so its efficiency will always be higher in optimal conditions where there is more light available.

## 5. How can I improve the efficiency of a solar cell in the dark?

The efficiency of a solar cell in the dark cannot be improved, as it is limited by the lack of light. However, you can improve the overall efficiency of a solar cell by optimizing its design and using materials that have higher conversion efficiencies in low light conditions.

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