Science Buddies: "Ask an Expert"

My project is The Effect of Color and Intensity of Light on Solar Power. Any ideas of how to do my project? Is there anywhere I can find color filters? Any other help will be appreciated!

leon.hu wrote:My project is The Effect of Color and Intensity of Light on Solar Power. Any ideas of how to do my project? Is there anywhere I can find color filters? Any other help will be appreciated!

Hello, Leon!

As for ideas for the project, I think you need to answer for yourself the question, "What effect would you like to measure?" Once you know what you'd like to measure, the choice for how to measure it becomes much easier.

Filters seem easy to find. Is what you're asking something other than finding a selection of plexiglass in different colors?

You also need to consider how you are going to vary intensity.

In general, when doing experiments like this, you want to control your experiment to the point where you are only changing one thing at a time from test to test. For example, you probably want to keep the intensity, distance, and angle constant while varying the color filter only. Then change the intensity to another value and repeat the color filter tests. And so on.

Thanks for your comments! Yes, I will follow what you stated in your last reply! But my budget is tight: around $15. And I need a good solar cell and color filters. Do you know which online or retail store sells cheap filters and solar cells?

P.S. I am going to have a lot of trials with varied constants each trial.

leon.hu wrote:Thanks for your comments! Yes, I will follow what you stated in your last reply! But my budget is tight: around $15. And I need a good solar cell and color filters. Do you know which online or retail store sells cheap filters and solar cells?

P.S. I am going to have a lot of trials with varied constants each trial.

I have not purchased either one, so I don't have experience to share. Radio Shack might have some of what you need - certainly the solar cell. You might try craft or photography stores for the filters.

My favorite online store is http://scientificsonline.com/, but I don't see anything in your budget.

johnsteele wrote:My favorite online store is http://scientificsonline.com/, but I don't see anything in your budget.

Hey, johnsteele! That's actually a great site!

If you search for "solar cell" and sort by price, they have solar cells priced as low as $2.95! If you search for "filter" they have a set of small acrylic filters in 5 different colors for $7.95. Not bad! Thank you for the pointer!

(Leon - make sure your filters are large enough to either cover the solar cell or cover the light source. Your results might be skewed if you don't run all the light through the filter. Those in the $7.95 set are only 5 cm square.)

Yeah,

I like the color filter idea, but I ordered a free color filter booklet that has many different color filters. So I am going to see how those work out first... As for the solar cell, I might just buy a silicon solar cell for $5 at Radio Shack (So I don't have to mess around with the shipping...)

Um... the small acrylic filters in 5 different colors for $7.95. Are they 5 cm area or 25 cm area? My solar cell is 32.625 cm area. But the actual working "cell" area (the blue stuff) is only 4.5 x 5.5. Should I buy a new solar cell? If so, I don't have a soldering iron so I can only buy solar cells with wires connected already. I have a voltometer at home with alligator clips.

leon.hu wrote:Um... the small acrylic filters in 5 different colors for $7.95. Are they 5 cm area or 25 cm area? My solar cell is 32.625 cm area. But the actual working "cell" area (the blue stuff) is only 4.5 x 5.5. Should I buy a new solar cell? If so, I don't have a soldering iron so I can only buy solar cells with wires connected already. I have a voltometer at home with alligator clips.

I believe that the small color acrylics were 5x5. If you place the filter close to your light source so that all the light that hits the solar cell passes through the filter I think you will be fine.

You could also cut out a rectangle from a piece of black paper (or any opaque paper for that matter) and tape the filter to the paper covering the hole. That way, any light emitted from the lightbulb that falls on the solar cell will have to come through the filter.

Leon,

Sounds like a great project, and the posters above have given some helpful advice.

I see your project is tited "The effect of color and intensity of light on SOLAR power"; does this imply you plan on using the sun as your light source? Or, do you plan to use an artificial source, and if so, what are you considering?

Keep up the good work!

Adam

For Adam's question, I am not using the sun as a source. I am using a 100 watt light, a 75 watt light, and a 25 watt light. Thanks for your compliments!

Yes, I think I will buy the filters on the website you mentioned! Thanks for the idea!

What length should I put my filter away from the light? What length should I put my solar cell from the filter?

leon.hu wrote:What length should I put my filter away from the light? What length should I put my solar cell from the filter?

Hi, Leon!

The distance is up to you. You might make some measurements with all three light sources to detemine a fixed distance where you get decent output for all bulb sizes and filters.

I thank you guys for your help!

I just finished my introduction to my science paper, but I haven't started experimenting yet. Is this enough information for my introduction?

Introduction:
The sun’s energy makes the world go round, but how? Most of our energy comes directly or indirectly from the Sun in the form of solar energy. However, when people think of solar energy, they think of massive fields of silicon solar cells, converting sunlight directly to electricity. That is not the case, though, with most of the solar energy used. Plants for example, take in energy from the sun, solar energy, to go through photosynthesis. The solar energy absorbed supplies chemical energy for a plant to grow. We need plants as food in order to live. When we are eating plants, we are eating the chemical energy in the plant (“Solar Kit� 1-21).
So plants take in solar energy and convert it to chemical energy, and people eat the chemical energy in the plants, right? However, that is only a very limited part of solar energy. Solar energy usually means the direct or indirect use of sunlight to produce heat or electric power. It is used around the world to supply energy for various minor jobs. The sun’s energy is almost unlimited, but it is sparsely scattered over a broad area and is expensive to collect and convert. People can capture solar energy with devices that change the solar energy into heat or electrical energy. For example, flat-plate collectors convert solar energy into heat energy, and photovoltaic solar cells convert solar energy into electric energy. There are two primary ways that solar power can be converted into electric power: directly with a procedure called photovoltaic conversion, or indirectly by solar thermal conversion, which converts solar energy to heat energy and then to electric energy (“Solar Energy�).
The photovoltaic solar cells obviously seems to have the upper hand because they can directly convert solar energy to electric energy. Nevertheless, solar cells are expensive and waste about 75 percent of the solar energy accumulated in the conversion process (Satchwell). Photovoltaic cells are able to produce electric current directly from sunlight with the photovoltaic effect, an occurrence in which solar energy causes electric charges to surge through layers of a conductive material to produce an electric current. Alexandre Edmond Becquerel, a French physicist, discovered the photovoltaic effect in 1839. Alexandre submerged two metal plates in a solution and detected a small voltage when one of the metal plates was exposed to direct sunlight (“Solar Energy�).
Have you ever seen the bluish tint on some silicon solar cell? But what does color have to do with the amount of solar power generated? Each color in the visible spectrum has a different wavelength. For example, the blue color has a wavelength of 400 nanometers, and the red color has a wavelength of 700 nanometers. We consider light as a stream of particles of photons. A single photon of one color is different from a photon of another color only because of its energy and wavelength. The shorter the wavelength of the color, the more solar energy it will produce. The longer the wavelength of the color, the less solar energy it will produce (“Light�).
Scientists measure the intensity of light in units called lumens. Watts only measure the amount of electric power used by a lamp, not how much light it produces. For example, a 100-watt incandescent light bulb may provide only ¼ as many lumens as a 100-watt fluorescent tube. So it is important to keep the kind of light bulb constant or else the data of this project will be scattered (“Lighting�).