# Solar Cell Physics Coursework (Calculating Internal Resistance)

• elyas22
In summary, the conversation is about calculating the internal resistance of a solar cell using a circuit setup with a voltmeter, ammeter, and variable resistor. The goal is to obtain a graph that can give the EMF and internal resistance. However, the current and voltage are not changing as expected, resulting in a horizontal line on the graph and an implication that the internal resistance is 0. To get accurate results, the experiment needs to be repeated with smaller values of resistance and taking into account that the voltage-current curve for a solar cell is not a straight line.
elyas22
Basically I want to Calculate the internal resistance of a solar cell.

I set up a circuit with a voltmeter across the solar cell and an ammeter and variable resistor in series with the solar cell. The variable resistor is the load.

Image at http://elyaschaudhary.schools.officelive.com/video.aspx

As i change the resistance the value of current changes which is GOOD
However the Voltage stays the same BAD

This results is a graph with a horizontal Line implying that internal resistance is 0. BAD

I need the current and voltage to change i think to get a graph which will be able to give me the EMF and Internal resistance.

Could some one please explain how this is done

Thank you very much

Elyas

Last edited by a moderator:
How low in resistance did you go? If you short out the solar cell, you will definitely get a lower voltage.

If you replace the solar cell with a voltage source (V) and an internal resistance (r) in series, then calculate the measured voltage (V1), you will see that a constant V1 just means that the internal resistance r is small compared to R. You will need to do the experiment again with smaller values of R that do cause a change in V1 in order to calculate r.

Also, the v-i curve for a solar cell is not a straight line.

## 1. What is the purpose of calculating internal resistance in solar cells?

The internal resistance of a solar cell is an important factor in determining its efficiency and overall performance. By calculating the internal resistance, scientists can better understand how the cell converts sunlight into electrical energy, and make improvements to maximize its efficiency.

## 2. How is internal resistance calculated in solar cells?

Internal resistance in solar cells can be calculated using Ohm's Law, which states that resistance equals voltage divided by current. Scientists can measure the voltage and current of a solar cell under different conditions and use this formula to calculate the internal resistance.

## 3. What factors affect the internal resistance of a solar cell?

There are several factors that can affect the internal resistance of a solar cell. These include the material and design of the cell, temperature, and the amount and quality of sunlight it receives. Changes in any of these factors can impact the internal resistance and overall performance of the solar cell.

## 4. How does internal resistance impact the efficiency of a solar cell?

Internal resistance can decrease the efficiency of a solar cell by reducing the amount of current that can flow through it. This is because the internal resistance acts as a barrier to the flow of electricity, causing some of the energy from the sunlight to be lost as heat instead of being converted into electricity.

## 5. Can internal resistance be reduced in solar cells?

While internal resistance is a natural characteristic of solar cells, there are ways to reduce its impact on efficiency. This can include using materials with lower resistance, optimizing the design of the cell, and controlling temperature and sunlight exposure. Ongoing research and advancements in solar cell technology aim to further reduce internal resistance and improve the efficiency of solar cells.

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