Solar Cell Current increases as Resistance increases Problem

In summary, the website said that increasing the resistance would result in an increase in the amperage, but this did not seem to be the case when measuring with a multimeter.
  • #1
PVJ2016
3
1
Hi everyone, so I'm trying to achieve IV curves based on how this website had done below:
http://www.voltaicsystems.com/blog/solar-charger-tutorial-part-2/

But whenever I increase the resistance, the amperage increases rather than decreases! For example, when I use a 500 ohm resistor the amperage is 500 uA but when I use a 3.6 ohm resistor the amperage is 30 uA. The voltage seems to increase when more resistance is applied so nothing wrong there... could this be a problem with my multimeter? I tried this with two different solar cells and both have the same issue. BTW, I am a total noob when it comes to this stuff so anything is much appreaciated :)

also, this is how I am hooking up the resistors:
http://www.mtmscientific.com/solar4.jpg
 
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  • #2
For amperage measurements you want the multimeter connected in series, not in parallel. What's happening here is that some of the current is flowing through the resistor and some of it is flowing through the multimeter, and the multimeter is reporting only the fraction that is flowing through it. Google for "ammeter parallel" for more on this.

For the voltage measurement, the parallel connection is fine; you're comparing the voltage at two points so you just need a probe at each point. No noticeable current flows through a multimeter doing a voltage measurement.
 
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  • #3
Nugatory said:
For amperage measurements you want the multimeter connected in series, not in parallel. What's happening here is that some of the current is flowing through the resistor and some of it is flowing through the multimeter, and the multimeter is reporting only the fraction that is flowing through it. Google for "ammeter parallel" for more on this.

For the voltage measurement, the parallel connection is fine; you're comparing the voltage at two points so you just need a probe at each point. No noticeable current flows through a multimeter doing a voltage measurement.
 
  • #4
Thank you so much! I just did what you said and it worked :) Now I can finally get some data!
 
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1. How does resistance affect the current in a solar cell?

The higher the resistance in a solar cell, the lower the current will be. This is because resistance is a measure of how much a material opposes the flow of electricity. So, as resistance increases, it becomes more difficult for current to flow through the solar cell, resulting in a decrease in current.

2. Why does increasing resistance in a solar cell decrease current?

In a solar cell, current is produced when photons from the sun's rays knock electrons loose from atoms in the cell's material. These electrons then flow through the material, creating an electric current. However, as resistance increases, there is more opposition to the flow of these electrons, making it harder for them to move and resulting in a decrease in current.

3. Can the resistance in a solar cell be too high?

Yes, if the resistance in a solar cell becomes too high, it can significantly decrease the amount of current produced by the cell. This is why it is important for solar cell manufacturers to carefully select materials with low resistance to ensure maximum efficiency.

4. Is there a way to increase current in a solar cell with high resistance?

One way to increase current in a solar cell with high resistance is by using a booster circuit. This is a circuit that is designed to reduce the overall resistance in the cell, allowing for more current to flow through. Another option is to use a material with lower resistance in the construction of the solar cell.

5. How does the resistance of a solar cell affect its efficiency?

The resistance of a solar cell plays a significant role in its efficiency. A higher resistance means that more energy is lost as heat, reducing the overall efficiency of the cell. Therefore, it is important for solar cell manufacturers to carefully consider the resistance of the materials used in order to achieve the highest possible efficiency.

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