Solar Cars

[tomboy]

Hello everyone,

I need help on a project that I have gotten from Science Buddies, but have modiefied it.

My question is from the project Solar Speedway. I have researched a lot, but couldn't find what I needed or the answers I needed.

1. How do solar cells change sunlight to electricity?
2. What happens if temperature or conditions interfere with the speed of the car?

Those are my questions for now. Thank you.

[barretttomlinson]

Hi,

Here is a link to a pretty good discusion of your questions:

http://science.howstuffworks.com/solar-cell.htm

You can find lots more information by searching for “how solar cells work” in Google.com.
Hope this helps!

Barrett Tomlinson

[tomboy]

Thank you so much for your help! I really appreciate it barrettomlinson!
I am going to have more questions throughout my project, but you have really given me
a boost in my project. Thank you .

[tomboy]

I'm confused on what kind of project I'm supposed to do. I need help to see what other project I could do besides "Does weather/temperature
conditions affect the speed of my solar car?" I need to know what other things I can do to modifiy my experiment. I modified my project so that it can
do a good experiment to fit my grade level. So please help me!!!!!

[tdaly]

Hi tomboy,

I have merged your two topics together. Please keep all questions related to your project on a single topic; this allows the Experts to be better able to help you.

Good luck!

[gsv]

I'm confused on what kind of project I'm supposed to do. I need help to see what other project I could do besides "Does weather/temperature
conditions affect the speed of my solar car?" I need to know what other things I can do to modifiy my experiment. I modified my project so that it can
do a good experiment to fit my grade level. So please help me!!!!!

How about looking at things more specific than just 'weather', such as air pressure, wind speed, precipitation, etc.?

These links might help as well:

• http://www.crystal-clear-science-fair-p ... jects.html
  http://www.mysolarsecret.com/blog/diy-s ... experiment
  http://www.kidslovekits.com/projects/CA ... index.html

Good luck,

-gsv

[tomboy]

Hello,

Thanks on helping me on other questions and I have another one now. My question is " Does temperature affect the speed of a solar car?"
Mainly I am trying to find out if temperature does affect a solar car. I really want to get good information on this, because I can't find the
answer anywhere. I have found some information, but it wasn't reliable. I have searched through different search engines, books, catolog
cards, and other resources from friends and teachers, but I still can't find the answer. The websites I already have don't have the answers
I need (I even checked every single thing on all the websites!), but (again) I still can't find the answer. They are helpful, but I am in the
stage for more informationon other things and that is what I really need right now. So, if you can help me on that then that would be really
great!

Thanks!

[barretttomlinson]

Hi,

I do not believe a very good answer can be given to the question you are asking without specifying in detail the design of the solar vehicle in question, which you have not done. As a very general qualitative answer, you can suppose that the solar car will perform approximately the way the solar cells powering it will perform as temperature is varied. This question can be answered, though vaguely, although it also depends on the specific solar cell type being used.
For a very general answer see the Wikipedia article on solar cells:
http://en.wikipedia.org/wiki/Solar_cell

I presume you have already studied the Science Buddies Project Idea writeup on Solar Cell output vs. Temperature:
https://www.sciencebuddies.org/science- ... p012.shtml

Here are some results for a specific solar panel:
http://www.reuk.co.uk/Effect-of-Tempera ... Panels.htm

Here is a science fair project summary report on this topic:
http://www.usc.edu/CSSF/History/2003/Projects/S0711.pdf

You might find these sites useful:
http://engnet.anu.edu.au/DEpeople/Andre ... guide.html

http://www.energy.gov.bn/symposiumpaper ... 0Malik.pdf

http://pvcdrom.pveducation.org/CELLOPER/TEMP.HTM

http://quantum.soe.ucsc.edu/research/So ... Thesis.pdf

I hope this stuff helps even though it does not address directly the question of speed vs. temperature.

Best regards,

Barrett Tomlinson

[tomboy]

The answers that you have replied has helped, but it is too high for me and to much information that I don't know about. My direct questions are: 1. How exactly does parts of a solar cell convert sunlight to energy?
2. Does the process include anything with a greenhouse?

I don't really have good information on that so it would be great if you could help me.

[Gizzmo46]

Tomboy,

No worries.

You aren't expected to understand it all. Sometimes it is difficult for us to remember that you are still in grade school. The basic idea behind a solar cell is that energy from the sun ... which can be considered a "particle" called a photon can (in very special materials) have enough energy to smack electrons loose from atoms. This is kind of like bowling... if the pins (electrons) are too heavy (to tightly bound) they can't be knocked over bay the bowling ball (photons). However if the pins are the right size they can be knocked over. The next important thing to note is that electricity is just many electrons flowing in the same direction. So ... if we have enough sun energy hitting the right material, then enough electrons will be knocked loose that there will be an electrical current that flows through the material that we can harness! This our photovoltaic energy!

About the green house ... the energy from the sun does not increase ... in fact the glass or the material that they are made of will block some of the sunlight which reduces the energy from the sun or the number of photons. As a result the current or voltage out of your solar cell should decrease when in the greenhouse. Of course, that is what, I suppose, your experiment will show ... rather than a greenhouse you might just want to try different materials over your solar cells ... such as glass, plastic, etc.

I hope that helps. Sorry that things were not explained better earlier. If you have more questions please ask ... I will check in again tonight, tomorrow and next Saturday.

Heidi

[tomboy]

Thank you so much for that. It really helped me and I mean really! It has even answered some of my next questions.
My questions now are just to clarify everything.

So, photons (light particles) hit the cells of a solar cell and sort of have a knocking affect that knocks an electron off from an atom.
The knocked elevtrons are then sort of directed down to a battery or wherever the energy is stored and then used to run a motor to work the solar car.

Then, solar energy isn't made by heat absorbed into cells or like geothermal energy. Also, a real question right now is: Are the atoms the solar panel and
so the sunlight is striking it? and If the atoms isn't the solar panel then where is it?

If the clarification isn't correct then please correct me to help me understand. I have to try and understand as much as possible as quickly as possible,
because my school's schedule is untimely.

Thanks a lot.

[Gizzmo46]

Tomboy,
You are on the right track!

You are correct it is not heat that "knocks" the electrons off the atoms (or molecules ... a combination of atoms) but light or photons. What is important to understand about photons is that they can have different frequencies (red and blue light have different frequencies ... hence the different colors). Also, to knock the electrons off the atoms or molecules a specific frequency of photon is required. As a result the particular material used in the solar cell will respond better to one particular frequency of light.

About the solar panel itself and what atoms are excited ... The solar panel will be composed of a number of materials ... probably some backing to give it support and some clear coat to protect the material of interest. Somewhere in between will be the material of interest which is composed of the atoms or molecules which have electrons that can be excited by sunlight. This results in an electrical current that flows through the material and into a battery or directly into an engine.

It sounds like you are getting! This is a tough concept to grasp and you are doing great!
Heidi

[tomboy]

Thank you so much for that. I would never have understood without your help. The only way I could undnerstand is by you turning the
hard terms to easy terms.

I would like to ask where you got the information. I want to know, because I would like to research more on where you found the information.
If you could give me the source like a book or a link, it would be very helpful.

Thank you so much.

[tomboy]

Hi,

I need some advice on the experiments stage. I have just finished putting together my solar car and when I tested it, it didn't work.
I redid everything and followed all the directions exactly the way the directions showed me. I even tried doing different solar cars to work,
but didn't work. So if you could please give me some tips that would be great.

Also, the solar car I have right now is from
http://www.klutz.com/catalog/product/3108

So, if you could think of any tips and problems then please post it.

Thank you!

[Craig_Bridge]

You've already done the obvious, follow the directions again and see if you've missed something obvious the first time. At this point, you are going to have to some testing to see if you can isolate the problem. Do you have access to a multi-meter? If so, you can disconnect the solar cell from circuit and measure the voltage it produces using a DC-volt scale. The link you provided claims it is a "one volt" cell. That isn't much voltage to run a motor. If you don't get any voltage reading and you are in bright sunlight, then there is something wrong with the solar cell or your meter or the connections between them. You can test out your meter by disconnecting it from everything, putting it on an ohms scale and touching the two test leads. You should get a reading of close to 0 Ohms if the meter is functioning.

Even if you don't have a meter, what happens if you briefly connect a new 1.5 volt AA cell directly to the motor with the motor out of the car so it doesn't have to turn anything but itself? Does the motor turn? If not, try giving the motor a bit of an assist by manually turning it and see if it starts turning. If not, try reversing the battery and repeating. If it still won't turn, then there is something wrong with the motor, the battery, your connections between them or the motor takes more than 1.5 volts to run.

If you have a multi-meter, with the battery and solar cell disconnected, put the meter on the smallest ohms scale and measure the resistance of the motor. Switch the leads and see if the reading changes. If both readings are very high, then either the motor is bad or you have a bad connection.

Assuming all of these steps worked (showed up no problems) and you have a meter, hook it all back together and measure the voltage across the motor. If it is less than half a volt, then the solar cell isn't producing enough current to turn the motor.