INTRODUCTION
Our sun is very important; it drives climate and weather, and is responsible for
life on Earth as we know it. Ultimately, the sun is one of the most powerful sources of
energy we know of. The amount of energy that hits the earth from the sun could power
1,740,000,000,000,000 (a quadrillion) lightbulbs! One form of the sun’s energy you are
very familiar with is heat. The sun shining down on us on a hot summer day can transfer
so much heat that we often quickly seek out shade. When it is a cold Chicago day, we all
gladly walk on the sunny side of the street to warm ourselves up a bit. People have used
the sun as a source of heat for many years and have discovered great ways to harness this
heat. A good example is that of a greenhouse, where energy from the sun travels through
the glass of the greenhouse and heats its surroundings. The heated soil, plants, and air
cannot escape back through the glass, so effectively the heat is trapped (an analogous
situation is what happens to your car in a parking lot on a hot sunny day when you’ve left
your windows rolled up). In ancient Greece people even built homes designed to get the
most sunlight in the winter months, and today the there is a large effort to build efficient
windows in homes that maximize the sunlight that goes through in winter, and minimize
the amount that goes through in summer (see figure 1).
Figure 1: The proper placement of overhangs can maximize the sunlight received in winter and minimize
the amount received in summer. These overhangs plus the placement of proper insulation serve as a smart
and free way to trap heat in the house. More information and this picture can be found at :
http://www.newenergy.org/sesci/publications/pamphlets/passive.html
Imagine what we could do if we could always efficiently harness energy from the
sun in the form of heat! We could stay warm in the winter without escalating our heating
bill, we could heat our water, and we could also use the heat to help us with something
most of us experience everyday: cooking. Trapping sunlight to warm food is an idea that
has been around for a long time by building solar ovens, or insulated containers that, like
a greenhouse, trap heat that comes from the sun’s energy. Today, there is a large effort to
spread solar ovens to developing countries where fuel for cooking is hard to find and not
often available. Today you will get a first hand experience on how to trap the sun’s
energy in the form of heat by building a solar oven out of a pizza box, and using it to
cook some of our favorite foods.
Heat however, is just one example of what the sun’s energy can be transformed in
to; can you think of other forms? If you want to discover another form of energy from the
sun, just look outside at the trees, grass, and plants that prosper in the sunshine. The green
plants you see are using photosynthesis, or the conversion of sunlight into chemical
energy that sustains the plant. One of the byproducts of photosynthesis is oxygen, which
we all breathe and need to survive. We will be also be exploring this process in the lab
today and in the extension activities.
Heat from the sun and photosynthesis are familiar concepts that affect our daily
lives. However, one aspect of the sun’s energy that we will explore in this lab that might
not so familiar is how we convert sunlight into electricity. Electricity is an important part
of our lifestyle and is used to power many of our appliances. As such, the demand for
electricity is high, and it takes energy to produce the electricity. One of the benefits to
producing electricity from the sun is that sunlight is always available and free to use
(except in Chicago-like climates where it is often cloudy and rainy). The main technology
for converting sunlight to electricity is a photovoltaic cell (PV cell) or solar cell. In this
lab we will be exploring how such a device works and pros and cons of using this
technology.
In this lab we will familiarize ourselves with how to trap the solar energy either in
the form of heat via a solar oven or electricity via a solar cell. We will talk about the
concepts of sustainable energy and energy efficiency. Overall, by the end this lab you
should understand the wide range of ways the sun’s energy can be harness and its use in
our daily lives.
BUILDING A SOLAR OVEN
In this activity we will build our own solar ovens from a range of materials
including but not limited to pizza boxes, foam, aluminum foil, cardboard, plastic wrap,
glass, cloth, black construction paper, and basic supplies like tape, glue, and scissors.
Though the basic design is outlined below, the goal for this lab is to think critically about
what would make a good solar oven and to effectively use the given materials in creative
ways to improve this basic design. We also have a larger solar oven that can sustain
higher temperatures then the ones we will be building today, thinking of why this oven
gets hotter will be clues to help you with your design. One thing you might want to think
of is the effect of insulation to better trap heat. After building our ovens, we will leave
some treats to cook in them. When we come back, we not only enjoy a delicious treat but
see how hot our ovens got and which design of oven worked the best.
PROCEDURE:
1) The basic idea is to start with a pizza box where food can easily be placed in
and removed, and light can always get in. The set up shown in figure 2, where a flap in
the top of the pizza box was created by cutting three sides of a square and folding back
along the fourth, is an efficient way to start this process. Go ahead and try doing this.
Figure 2: Cutting along the dotted lines on the picture on the left side and folding back along the nondotted line creates a panel that can be propped up, as shown on the picture on the right side.
From: http://www.solarnow.org/pizzabx.htm.
2) We want as much light from the sun as possible to go into the pizza box, the
more sunlight we get, the hotter our oven will get. If the sun is directly above, you might
imagine that the opening in our pizza box lying flat on the ground will be getting as much
light as it can, as long as the flap is not in the way. However, what if the sun is not
directly overhead, but at some angle in the sky? How could we maximize the light that
goes into our oven in that case? If we had something to reflect sunlight, we could indeed
reflect sunlight straight into our oven! Your goal for this step is to find the material out of
those provided to you that would be the best at reflecting sunlight. If you attach this
material to the inside of the flap you cut out in step 1, you should will have a reflective
panel that can be set up at different angles to maximize the sunlight we capture.
3) What makes a greenhouse work? As we discussed earlier, energy from the sun
is transformed to heat in the soil, plants, and air, and this heat is trapped because the hot
air cannot escape through the glass enclosure of the greenhouse. Our solar oven should
optimally work the same way. We want to heat the food and the air surrounding the food
and like the case of the greenhouse, we don’t want that hot air to escape. Can you think of
a way to make our pizza box oven more like a greenhouse? Is there a material that would
let light in but not let hot air out? A good idea would be to line this material over the
opening of our oven (like putting a glass roof on the greenhouse).
4) Following the logic of step 3, not only do we want light to get in and hot air to
get trapped, but we also want light to stay in our oven for a while. If light enters and
bounces around a bit (meaning reflects from a few reflective surfaces), we are heating the
air more than we would if it just came in and got absorbed right away. Reflective coating
(maybe the same thing you used on your panel) inside the box will help light bounce
around. However, though we want light to bounce around, we don’t want light to bounce
right back out of the solar oven! So any place where light could reflect from and where if
reflected could bounce out of the oven, should be covered with something that absorbs
light well. Covering this surface with a good absorber will ensure light bouncing directly
out of our oven won’t happen. What out of your given materials do you think absorbs
light the best? How can you tell? Use this material to line the surface of your oven where
light could bounce out.
5) After these steps our basic solar oven is complete. The last thing to do is place
the oven in a nice sunny place. You should also align the top flap so it reflects the most
light from the sun inside the oven, once you have it in the right position prop it up with a
stick or a ruler. Stick the food inside for cooking, and also place a kitchen thermometer in
near the food so we can record how hot your solar oven can get. We will come back to
these solar ovens later in the afternoon and see how our food turned out and also find out
which oven got the hottest!
QUESTIONS:
1.) What color you think good absorber should be in and why?
2.) It is 8:00AM on sunny day in June. The sun is not directly above your head but
rather close to the horizon on Southeast. How would you place your solar oven
with the reflector? Draw if necessary.
3.) Let’s suppose you are making pizza using the solar oven, and every 10 minutes
you open the solar box and peek inside to check your cooking. After half an hour,
do you think the temperature inside the solar oven will be as hot as the oven that
kept close during cooking? If not, why?
DEMONSTRATING PHOTOSYNTHESIS
As mentioned earlier one of the ways energy from the sun is harnessed is in the
process of photosynthesis. The most familiar living things that undergo this process are
green plants, but algae and some bacteria undergo photosynthesis as well. Photosynthesis
is a chemical process so it represents the transfer of sunlight into chemical energy, rather
than heat. Through this process plants, algae and bacteria ultimately use sunlight to
produce sugars and carbohydrates (and of course the fact that we eat plants to get those
carbohydrates only emphasizes the importance of the transfer of sunlight to chemical
energy). For a plant, the full chemical reaction going on during photosynthesis is:
Carbon dioxide + Sunlight + Water  Oxygen + Glucose (basically sugar!).
Figure 3: A diagram showing the basic ingredients of photosynthesis. From
http://grapevine.net.au/~grunwald/une/KLAs/science/irrigation-photosynthesis.gif
So when you water your plants at home and place them on a sunny windowsill
you are providing them with the necessary tools to create chemical energy! And plants
return the favor all over the earth by removing carbon dioxide from the air and releasing
the oxygen that we breathe in. In this section of the lab, we will demonstrate the creation
of oxygen by photosynthesis and show that indeed energy from the sun is the key
ingredient.
PROCEDURE:
1) You will be provided with a plant called Elodea, which is an aquatic plant. The
first step once you have been given this plant is to cut the stem at an angle and lightly
crush it. If you look at an Elodea submerged in water while it is in the sun or near a bright
light, what do you notice? You may observe tiny bubbles; can you guess what these are
from?
2) Now take your individual Elodeas and place them in a jar, put a glass funnel
over the entire Elodea and fill the jar with water. Fill a test tube to the top with water.
Placing your thumb over the top of the tube, slowly flip the test tube over and lower in
under water in the jar. Then remove your thumb and place the test tube over the pointy
end of the funnel. We have essentially created a contraption that should trap any gas
released from the plant (like oxygen). Bubbles released should go upward through the
funnel and collect in the test tube.
3) We will leave half the contraptions you created in a sunny place and half of
them in a dark closet for about one day. We will test the differences between the
contraptions left in the sun and those in the closet by lighting a toothpick on fire, briefly
blowing it out, and placing the hot ember into the test tubes. Observing the results, what
do you think has happened? Try to work out clearly in your mind how what we did has
demonstrated the use of the sun’s energy.
QUESTIONS:
1.) Why do you think we kept half of the jars in a dark closet for about one day?
2.) Why do you think photosynthesis is such an important process to plants?
EXPLORING SOLAR CELLS
A Solar, or “Photo-Voltaic” (PV), Cell is a device that single-handedly converts
light into electric current. As you should know already from science class, energy can
exist in a variety of different forms. Electricity is one of the most widely used forms of
energy in our society, and so a Solar/PV Cell has the advantage of converting sunlight
directly into a form of energy that we use extensively. A Solar/PV cell works via a
“photo-electric” process in which photons (particles of light) collide with electrons in
atoms and knock them loose. The material the PV cell is made of is called a
semicondutor, which is basically a material that has its own internal electric field,
meaning one side acts like a positive charge and the other acts like a negative charge (see
figure 4). You may have heard that “opposites attract” and just like the north pole of a
magnet is attracted to the south, a negative charge is attracted to a positive one. When the
negatively charged electron is knocked loose by the photon, it only moves in one
direction: towards the positive end of the semiconductor. Thus the complete process
going on in a PV cell is that photons from a light source knock out electrons from their
host atoms, and these electrons all flow in the same direction. This uniform flow of
electrons is called a current, the same as the electric current that flows through the wires
of your household appliances. In fact, this flow of electrons is electricity!
What factors go in to determining how well a PV cell works? Photons from light
can have different energies, corresponding to different colors of light, and the electrons in
the PV cell are knocked away from their atoms only by photons with a specific energy
which is dependent on the atom (some atoms hold their electrons tighter than others).
Therefore, not all photons will knock out electrons, only those with the right energy will
do so. Also even when the photons hitting the cell have the right energy, each hit doesn't
necessarily knock out an electron, some might reflect away from the surface, or hit a
place where there is no electron to knock out. Basically, PV cells have some efficiency
they work with, and most of the time this efficiency is low! In fact, most of the light that
hits a standard PV cell does not produce electricity – only a small fraction (~6%) of the
light energy is converted into electricity.
Besides the energy of the photons, another main factor that determines how well a
PV cell works is something called flux. The flux of photons on a surface can be thought
of the amount of photons hitting the surface per second. A neat way to visualize how flux
works is to imagine that a light source, like the sun (or a light bulb) shoots off photons
equally in every direction (see figure 5). The photons act just like tiny pebbles, traveling
a long the same path they were released at until they hit something. Looking at figure 5
you see that if you were standing near the surface of the sun as it was throwing out
pebbles you'd be in a lot more pain (i.e. there would be a lot more pebbles hitting you, a
higher flux of pebbles) than if you stood a bit farther away. Also if you were standing
some distance from the sun with a friend who was half your size, your friend would get
hit with less pebbles than you (he's a smaller target, he gets less flux of pebbles than you
do).
How then does flux relate to PV cells? Well, the more photons that hit the PV cell
the more electrons you send off! Thus higher flux hitting a PV cell should increase the
current the cell provides. All of our tests with solar cells in this section will investigate
the properties of flux discussed above and illustrated in figure 5.
Figure 5: A cartoon to illustrate flux. If the sun was throwing out pebbles (in reality it “throws out”
photons, little packets of light) equally in every direction, the flux of pebbles hitting an astronaut would
depend on his distance from the sun and his size. The top panel shows the effect of size: at the same
distance of the large astronaut, the smaller one gets hit with less pebbles per second, i.e. there is less flux of
pebbles on the tiny astronaut. The bottom panel shows the effect of distance from the source of the pebbles:
the same size astronaut placed at a larger distance from the sun would be in a less concentrated beam of
pebbles, so the pebbles that hit the guy at the bigger distance per second (or the flux of pebbles) would be
less. Note these are opposite effects; the bigger the area the astronaut takes up raises the flux of pebbles on
him is, while the bigger the distance from the sun you place him at lowers the flux of pebbles on him.
TESTING SOLAR CELLS : OPTIMIZING THE POWER OUTPUT OF YOUR CELL
Equipment: Solar Cell, Electric Motor, lamp with 200 Watt light bulb, meter stick,
paperclips, protractor
Before we begin with a few simple experiments, we should figure out exactly how
we will measure the power output from a PV Cell. If we wanted to be very technical, we
could use a device called a “multi-meter” to measure the electric current output of a given
solar cell, which would be measured in units of Amperes. However, it might be more fun
to measure the power output of your cell using a more interesting – if less standard – unit
such as “paperclips”. For these simple experiments you should attach the wires from
your Solar/PC cell to a small electric motor. You will use this motor to lift up a string
with some number of paperclips attached to it. The more power that the solar cell feeds
to your motor, the more paperclips the motor should be able to lift. In principal, we could
figure out how to convert our unit – paperclips – into a more standard current unit such as
amperes (but don’t worry – we won’t!).
TEST #1
You will first measure power output from solar cell while changing the distance between
the solar cell and the light source (lamp). This is just like moving the astronaut in figure
5 further out! What do you think is going to happen? Be sure to *move the lamp and not
the solar cell* - keep the solar cell stable throughout this part of the experiment. Start
with the lamp 10cm away from the solar cell and move it away in steps of 10cm until
your motor is unable to lift any paperclips. Record at each step in the table below how
many paper clips could be lifted at each distance the lamp was placed at. When you are
done recording data, plot the data on a graph with paperclips lifted as the y-axis and the
one over the distance squared of the lamp as the x-axis. The reason for making this plot
should be clear by the end of these activities. Comment on the trend, and the distance of
the lamp increases, what happens to the power of the solar cell?
Distance of lamp from Cell (cm)
10
20
30
40
50
60
70
80
90
100
# Paperclips lifted
TEST #2
Now instead of testing one solar cell as our light source moves farther away, lets try
keeping the lamp in the same place, and adding more than one solar cell together. This is
like making the astronaut in figure 5 larger. What do you think will happen? The
instructor will show you how you add the cells together to make an array of cells. As a
group, cells will be added until the original one cell has evolved to a 5x5 array. As we
increase add on more cells we will record in the table below the number of paperclips our
increasing grid of cells can lift. When you are done recording data, plot the points on a
graph with the effect area of the cell grid (the number of cells) on the x-axis and the
number of paperclips lifted on the y-axis. Comment on the trend of this graph. What is
happening? Compare this to the graph you made for test #1. What is the shape of these
graphs, and what does it mean? If you had to write down a formula for flux, what do you
think it would look like?
Grid of PV Cells # Paperclips lifted
1x1
2x2
3x3
4x4
5x5
TEST #3
Now you will measure how the *orientation* of your solar cell relative to the light source
affects the power output that it generates. First consider two possible extremes: would
your solar cell produce more current if it were pointed away from a light source or if it
were pointed directly at the light source? You will now experiment with the effect of
pointing your solar cell directly at a light source vs. pointing the cell partially away from
the light source. You will use angles to measure the orientation of the solar cell relative
to the light source - begin by setting your solar cell up such that the light-collecting
surface is pointed as directly as possible toward your lamp; we will call this position
angle=zero. Using the protractor as a guide, move the cell in increments of 10 degrees
from the lamp, making sure it is always kept the same distance away from the lamp (i.e.
the effects we explored in test #1 do not come into play). At each new angle measure the
output in terms of paper clips lifted. After you have recorded all your data, plot the points
on a graph with the y-axis as paperclips lifted and the x-axis as angle. Discuss the trend
you have discovered, and what does in mean in terms of flux?
Angle of cell relative to lamp
10
# Paperclips lifted
20
30
40
50
60
70
80
90
QUESTIONS:
1.) What energy form is the electric energy generated by solar cells converted to,
when the motor lifts up a string of paperclips?
2.) As you increase the distance between the solar cells and the lamp, how does the
number of paperclips that the motor can lift up change, and why do you think it
does?
3.) How about when you add solar cells together yet keep the lamp at the same
distance? What did the addition of more cells do to the number of paper clips
lifted?
4.) Are the two trends described in questions 2 and 3 the same or opposite? If you
had to place your solar cell at a certain distance (lets say it goes on a space
telescope which is made to orbit the earth), how could you improve it to get the
same power as a cell closer to the sun (let's say on a telescope orbiting around
Venus)?
5.) How does the orientation of the solar cell relative to the light source affect the
power output that the solar cell generates? How is this relate to flux?
6.) Do you know the reason for the seasons? Since the earth is tilted, different parts
of the earth get hit by different angles of sunlight as the earth traces out its yearly
path around the sun. The difference of the sun's light on Chicago in the summer
versus the winter is illustrated in the picture below. Which seasons (winter or
summer) is getting direct light? Think our orientation experiment, how do these
seasons related to flux? Can you riddle out why summer in Chicago is warmer
than the winter?
From: http://www.morehead.unc.edu/Shows/EMS/seasons.htm
7.) If the Earth was not tilted at 23.5 degrees from vertical, how would the seasons
change in Chicago, IL and why? Are the places in the world that always have the
same season? Why?
BUILDING A SOLAR CAR
(photo adapted from http://en.wikipedia.org/wiki/Image:IMG_0095.jpg [public domain])
Finally, we will use the solar cells that we have just studied to build a small, solarpowered car. We already know how a solar cell works, and we have used it to power an
electric motor. The next step is to connect it to an axle and a set of wheels. Our little
homemade car won’t be very fast, and if the sun isn’t out, it won’t go anywhere at all.
However, it is possible to make solar cars much faster. The photo above shows the
Momentum, a full-size solar car build by students at the University of Michigan. In 2005
it won the North American Solar Challenge, a race from Texas all the way to Canada,
with top speeds of 65 mph. Another example of a solar-powered car is the Mars rover,
used by NASA to explore the surface of Mars.
Equipment:
PROCEDURE:
Step 1:
Cut one popsicle stick in half, and glue the halves across the ends of two other popsicle
sticks, as shown on the left. Glue a fourth popsicle stick along a diagonal for better
support. Then glue the four bearings to the ends of the frame, as shown on the right.
Step 2:
Snap the small gear onto the motor. Next, solder the wires from the solar cell to the wires
from the motor.
Step 3:
Insert the axles in the bearings. Attach the two large gears to the front axle, and the two
foam wheels to the rear axle. Glue the gears and wheels in place on the axle, as shown
on the left. This is the bottom of your solar car. Next, turn the car over. Attach the
motor and solar cell, as shown on the right. The small gear on the motor should turn the
large gear on the axle of the car. Glue the motor and solar cell in place.
QUESTIONS:
1) Does your car move with the sun’s light alone? If so, congratulations! That was
very difficult!
2) How fast does your solar car move with a light bulb held close to the solar cell?
Can it travel up a slope?
3) (Advanced) The demonstration model travels slower, but needs less light.
Explain how the arrangement of gears in this model helps it travel with less
power.
BIG QUESTIONS:
1) What if the sun was very different? What if it was much brighter or much dimmer? In
fact in the current search for earth-like planets around other stars astronomers have
focused on looking at “M-dwarf” stars (stars much dimmer and much less massive than
our sun) rather than stars like the sun. Astronomers predict that these dwarfish stars will
be a much more likely detected host of a planet like earth than all other types of stars
will. You should recall that stars can also be different colors (just look at the nighttime
sky and you will see an array of blue, orange, white colored stars). Each of these different
colors corresponds to a different wavelength of light the star gives off the most of. Blue
stars give more blue and UV light, whereas orange colored stars give off more red light
and sometimes lots of infrared light. Write about how the mechanisms of solar power we
have discussed would change with a different sun (i.e. brighter and bluer, or perhaps
dimmer and red-ish). Note that all the mechanisms we have talked about are dependent
on a specific color of light. For example Chlorophyll, the substance responsible for
photosynthesis in most plants, absorbs blue and red light really well and leaves behind
green light (this is why plants are green). So perhaps plants on a planet around a different
type of star could be some color other than green! Get creative, and think about how a
new sun would change life on earth and the way we harness the energy from that sun!
(By the way, thinking about a different sun and different planets is not just science
fiction! Our own sun has been changing over its lifetime, and once it runs out of fuel for
nuclear reactions, it will eventually cool and expand to be come a “red giant” star. In this
phase of the sun’s life, it will puff out enough to actually engulf the earth’s orbit; what a
change indeed!)
Science Fiction: Luke Skywalker’s home planet Tatooine has two suns. Real life: Astronomers have
discovered many planets orbiting around binary (two star) systems, Tatooine may yet exist!
2) Think about the solar car you built, a handy device that doesn’t run out of fuel. It
would be nice if we could all drive solar powered cars around, but in Chicago especially,
the cloudy skies and summer rain make such a technology a bit out of reach. However, if
there was no atmosphere making rain and blocking the sunlight you might imagine that
our little cars would work very well! In fact such cars have been used to explore the
surface of Mars, a planet with almost no atmosphere. Have you heard of the Mar’s
Rovers (picture below)? These are two solar powered vehicles (really robots) that have
been exploring the surface of Mar’s for nearly 4 years! Their basic design is just like our
solar powered car. Imagine sending the cars we built to Mars. Write the features you
would add to our basic solar cell car that would make it an effective tool to explore Mar’s
surface and send information back to earth. Imagine you had a remote control to steer
your car, what could you as a driver do to ensure that the cars were working as efficiently
as possible? Thinking outside the box/planet, where else would you use solar powered
devices and why?
The basic layout of the Mars Rovers: the large board on
top is a solar panel, looks a lot like our car!
3) What if you had to design a house that ran on solar power? Let’s say you are building
it in the north, around a latitude of 40 degrees. Where would you place your solar panels?
From what we learned, would you tilt them or face them in any sort of direction? Based
on the forms of solar energy we discussed, think about what other things you could do
this house to make it efficient (i.e. how could you harness heat from the sun as well). You
might also want to think about the things you have learned from the other labs and
incorporate these into your design.
In general, solar panels of the size necessary to power a house are very expensive. Also
solar cells produce direct current, whereas the electricity we feed through our houses into
our appliances is in the form of alternating current. It would take energy to even convert
the direct current of solar cells into the alternating current we use. Furthermore, the
generation of solar power requires sunlight! You don’t generate much power on cloudy
days. With these considerations in mind, do you think it is worth it to make your solar
powered house? How and where would you use solar energy?
4) As previously mentioned, there is a large effort to distribute solar ovens to developing
countries. Fuel in such countries, such as firewood, is scarce and potentially dangerous
since in these counties a lot of firewood fueled cooking is done indoors and the inhalation
of the smoke given off can be toxic. The introduction of solar ovens would eliminate the
need for exhaustible fuel such as firewood, and would in general be a safer way to cook.
Yet many in these developing countries are opposed to the use of solar ovens. Many
claim that solar ovens don’t allow for the proper preparation of traditional cuisine.
Perhaps the cuisine of a certain region allows for the slow addition of ingredients, stirring
and mixing things in at different times as the dish warms over a fire. Since solar ovens
need to be kept so well insulated, opening and closing the oven to stir or add ingredients
isn’t really an option. Plus many claim solar ovens take much longer to cook than
cooking over a fire, though you can leave a solar oven unattended as it cooks (something
that can’t be done with firewood fueled cooking). Finally one of the major downfalls is
that when it rains, solar cooking is out of the question. With these pros and cons in mind,
putting yourself in the shoes of someone in a developing country, would you implement
solar oven technology into your daily life? Why or why not? Do you think there are other
issues with solar oven use than those outlined above? Which of the issues would be most
important to your decision? Can you think of anyway to resolve some of these problems?
OBJECTIVES:
After performing this lab, you should understand:

That the Sun is essential to life on earth.

That Solar energy is an ever-present and powerful energy source, and it can be
converted to other types of energy such as chemical, heat, electrical, and potential
energy

How to effectively trap the energy from the Sun, specifically via a solar oven

How some living organisms store solar energy in the form of carbohydrates via
photosynthesis

How solar cells convert solar energy to electrical energy which can be used to
power other devices:
o
o
o
o
Solar car
Pulley with a weight
Light bulb
Calculator

How to optimize devices in order to produce the best output power possible

How we get different seasons in a year with the Sun shining on Earth at different
angles

That light from the Sun comes in a wide range of wavelengths, and different
devices are tailored to work best in certain ranges.

That solar energy is an alternative form of energy that reduces the dependency on
fossil fuels and causes no damage to the environment.