What is solar energy?
Solar energy just means energy (light or heat) that comes from the sun. For example, plants use solar energy (light) to grow. Solar energy heats the inside of our cars during a hot and sunny day.
How can we use solar energy?
There are two basic ways that we can use solar energy. We can use the sun's energy to heat things--our houses, the water in our houses, the food in a solar cooker, and so on. This is called solar thermal energy. (Thermal means heat, so solar thermal energy just means heat energy from the sun.) The second basic way we can use solar energy is to turn light from the sun directly into electricity, using solar panels.
Solar electric panels are made up of something called silicon, the same thing that makes up sand. There is more silicon on the planet than almost anything else. Even though you can find silicon almost everywhere, making a solar panel is difficult and expensive. The silicon has to be heated to super high temperatures in a big factory, and then formed into very thin wafers. When sunlight hits a solar panel, it makes electrons in the silicon move around. (Electrons are teeny tiny specks--they're way too small for us to see, even under a microscope.) The electrons flow through wires that were built into the solar panel. And presto! We have electricity! We can do whatever we want with this electricity, run a calculator, a CD player, or, if we have big enough solar panels, a satellite! [Solar panels are also called photovoltaic panels. "Photo" means light and "voltaic" means electricity.]
When the sun stops shining on your solar panel, its electrons stop moving and electricity stops flowing. So what do you do if you want to be able to read or watch television at night? (But you don't watch television, do you?!) What stores the electricity in a flashlight? Right! A battery! And that's exactly what people do with solar panels... they attach batteries. The batteries are big, heavy, rectangular boxes, sort of like car batteries. Electricity from a solar panel flows into attached batteries while the sun shines, and then the stored electricity in the batteries can be used at night, or when the sun is behind the clouds.
There are two basic ways that we can use solar energy. We can use the sun's energy to heat things--our houses, the water in our houses, the food in a solar cooker, and so on. This is called solar thermal energy. (Thermal means heat, so solar thermal energy just means heat energy from the sun.) The second basic way we can use solar energy is to turn light from the sun directly into electricity, using solar panels.
Solar electric panels are made up of something called silicon, the same thing that makes up sand. There is more silicon on the planet than almost anything else. Even though you can find silicon almost everywhere, making a solar panel is difficult and expensive. The silicon has to be heated to super high temperatures in a big factory, and then formed into very thin wafers. When sunlight hits a solar panel, it makes electrons in the silicon move around. (Electrons are teeny tiny specks--they're way too small for us to see, even under a microscope.) The electrons flow through wires that were built into the solar panel. And presto! We have electricity! We can do whatever we want with this electricity, run a calculator, a CD player, or, if we have big enough solar panels, a satellite! [Solar panels are also called photovoltaic panels. "Photo" means light and "voltaic" means electricity.]
When the sun stops shining on your solar panel, its electrons stop moving and electricity stops flowing. So what do you do if you want to be able to read or watch television at night? (But you don't watch television, do you?!) What stores the electricity in a flashlight? Right! A battery! And that's exactly what people do with solar panels... they attach batteries. The batteries are big, heavy, rectangular boxes, sort of like car batteries. Electricity from a solar panel flows into attached batteries while the sun shines, and then the stored electricity in the batteries can be used at night, or when the sun is behind the clouds.
You have probably seen big panels on the roofs of houses. These panels are used to power the house with electricity provided by the sun!!!To read more about solar panels and solar energy, look at this excellent site on solar energy
How does a solar oven work?
We can use solar energy, or the heat from the sun, to cook our food in a solar oven. A solar oven is an insulated box with a transparent top and a reflective lid. The box usually has one or more reflectors with aluminum foil or other reflective material to bounce extra light into the interior of the box. The inside bottom of the cooker should be dark-colored or black. The inside walls should be reflective to reduce radiative heat loss and bounce the light towards the dark bottom. We can make our own solar ovens from our own pizza boxes or shoe boxes. Solar ovens are great because they save energy and minimize pollution. It is a lot of fun to cook and then eat your own pizza in your own homemade solar oven.
Make Your Own Solar Oven
What you need:
shoe box or pizza box (ask a pizza restaurant to give you one, a square box is best)
ruler
marker or pen
scissors
plastic wrap
aluminum foil
tape or glue (it should say 'non-toxic')
drinking straw or stick
black paper (newspaper may also be used as an alternative)
a sunny day
pizza bagels, hot dogs, or marshmallows with graham crackers (for s'mores)
1. Draw a square on top of the pizza box. Make it one inch away from the edges. Have an adult cut along three sides. Do not cut the line along the back of the box.
2. Make a flap by folding back along the uncut line.
3. Cut a piece of foil to fit the inside of the flap. Glue or tape the foil in place, shiny side out. If you put it on carefully, it will not wrinkle much. Press out any wrinkles with your fingers.
4.Cut the plastic to fit over the hole that the flap made. Make sure the plastic is much bigger than the hole. Tape the plastic to the box. Seal the plastic tightly so that the air cannot get out.
5. Cut another piece of foil to cover the bottom and sides of the box. Glue or tape the foil into place.
6.Cover the foil with black construction paper, and tape it into place.
7. This is what your finished solar oven will look like...
8.To cook something... lay a piece of foil in the center of the box. You can also use a napkin or paper plate. Put the hot dogs, pizza bagels, marshmallows/crackers, etc... on the foil.
9. Close the box. Open the flap of the box. Prop the flap open with the drinking straw or stick. Turn the flap towards the sun. You want the sun to reflect off of the foil and into the box. It may take about an hour to cook a hot dog; solar ovens are slow cookers.
Take a look here for more information on how to make solar ovens, and here for more information on solar cooking.
