# Internal Resistance of Solar cell

• noura17
In summary, when trying to measure the internal resistance of a solar cell, the only variable that can be changed is the resistance using a variable resistor. This can be modeled using an equivalent circuit with an internal shunt resistance and overall series resistance. To find the internal resistance, one can measure the voltage and current and use the equation Power = current * voltage. By plotting the voltage-current points and finding the intersection with the axes, the internal resistance can be calculated as voltage/current, with the voltage being measured without a resistor and the current being measured with a short-circuited power cell. The Rload power is at its highest when Rload = Rinternal.
noura17
Hi,
I am trying to do coursework on measuring the internal resistance of a solar cell. The light intensity on the solar cell is not going to change so the only thing that can be changed is the resistance as a variable resistor is used.But I am not sure how to find the internal resistance when I don't know the current or voltage. Can anyone please help...

Do you mean that you are trying to work out an overall model for a solar cell, and are trying to figure out how to model a resistance term?

A solar cell (a big photodiode) does have a bulk resistivity, in addition to outputting a photocurrent. It's mainly from just the resistance of the silicon itself, I believe.

I just bounced to wikipedia, and they have some good pages about solar cells. Here's the page with an equivalent circuit:

http://en.wikipedia.org/wiki/Solar_cell#Equivalent_circuit_of_a_solar_cell

Looks like there's an internal shunt resistance (probably for the internal leakage current) and an overall series resistance. Now, given that equivalent circuit, what ways can you think of to measure those two resistances?

I think i have to find:
Power = current * voltage.

theoretically if you make a graph voltage-current and you put all your resistor measuring points on it then you draw a line trough those point. that line will cross the voltage and current axis.
if you take tose two values then you have Rinternal= voltage/current
The voltage should be the voltage that you measure without resistor attached, the current should be the current when you short-circuit the the power-cell.

## What is the internal resistance of a solar cell?

The internal resistance of a solar cell refers to the resistance that the solar cell itself offers to the flow of current. It is a property that affects the overall efficiency and performance of the solar cell.

## Why is the internal resistance of a solar cell important?

The internal resistance of a solar cell is important because it affects the amount of power that can be extracted from the solar cell. A lower internal resistance means a higher power output and better efficiency.

## How is the internal resistance of a solar cell measured?

The internal resistance of a solar cell can be measured using a multimeter. By measuring the voltage and current produced by the solar cell at different loads, the internal resistance can be calculated using Ohm's law (R = V/I).

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

The internal resistance of a solar cell can be affected by various factors such as the material used in the solar cell, the temperature, and the size and design of the solar cell. These factors can also impact the overall efficiency and performance of the solar cell.

## Can the internal resistance of a solar cell be reduced?

Yes, the internal resistance of a solar cell can be reduced by using high-quality materials, optimizing the design and size of the solar cell, and keeping the temperature at an optimal level. Regular maintenance and cleaning can also help reduce the internal resistance and improve the performance of the solar cell.

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