## Solar Pannel Power as a function of light intensity

Ask questions about projects relating to: aerodynamics or hydrodynamics, astronomy, chemistry, electricity, electronics, physics, or engineering.

Moderators: MelissaB, kgudger, Ray Trent, Moderators

### Solar Pannel Power as a function of light intensity

Hello,
I have just conducted an experiment involving 5 light bulbs ( of different intensities), a solar panel and a 50 Kilo-Ohm (ohmic) resistor in order to find out the relation of light intensity and the solar panel's output power. I hooked the resistor to the solar panel and I put a lamp (whose light bulb I changed several times) at a constant distance from the panel. According to what I have read, since the frequency of the incident light does not change, the voltage should stay the same but the current should change. However, what I got was that both. The current and voltage would increase, which makes sense since in order for the current to become bigger, bigger voltage is needed. However, my REAL PROBLEM is that the solar panel's power output was NOT directly proportional to the intensity of the light. The graph of power vs light intensity looks like a parabola instead of a strait line. Shouldn't the power be directly proportional to the light intensity?? Why am I getting these results? Have I done anything wrong?

jmki

Posts: 2
Joined: Mon Dec 24, 2012 5:48 am
Occupation: student
Project Question: solar panel power output as a function of the intensity of the incident light.
Project Due Date: January 7th 2013
Project Status: I am finished with my experiment and analyzing the data

### Re: Solar Pannel Power as a function of light intensity

Let us know more about how you made your measurements, what loads you used, and how you calculated your results. If your panel was specified as a 12 volt unit capable of producing 100 milliamps in bright sunlight (the seller would want to advertise the best performance) you could infer that a realistic load resistance might be in the range of 50Ω to 200Ω (certainly not 50KΩ). You could easily calculate an optimized load value through experimentation. Good luck, we'll be happy to help when we know more.

Rick Marz
rmarz
Expert

Posts: 496
Joined: Sat Oct 25, 2008 1:26 pm
Occupation: Technology Consultant
Project Question: n/a
Project Due Date: n/a
Project Status: Not applicable

### Re: Solar Pannel Power as a function of light intensity

In the experiment, my goal was to find some relation between the intensity of the incident light and the solar panel's output power. Since I was just trying to find a relation between the two, I thought that it would make no difference if I used a different resistor. However my measurements are:

Lumens __ Voltage (V)__ Current (mA) __ Power (W)
170________11,42_______ 0,227________ 0,00259
405________13,23_______ 0,263_________ 0,00348
915________15,29_______ 0,304__________0,00465
1320_______15,9________ 0,318 _________ 0,00506
1980 ______ 16,6 _______ 0,331 _________ 0,00549

I would expect a linear relation between the power and the light intensity. However the results were not what I expected.

Please tell me if I have made any wrong measurements or if I should expect these results.

Thank you.
jmki

Posts: 2
Joined: Mon Dec 24, 2012 5:48 am
Occupation: student
Project Question: solar panel power output as a function of the intensity of the incident light.
Project Due Date: January 7th 2013
Project Status: I am finished with my experiment and analyzing the data

### Re: Solar Pannel Power as a function of light intensity

Rick Marz
rmarz
Expert

Posts: 496
Joined: Sat Oct 25, 2008 1:26 pm
Occupation: Technology Consultant
Project Question: n/a
Project Due Date: n/a
Project Status: Not applicable