This unit takes students through several introductory lessons designed to gain a better understanding of the 'nano' scale as it relates to the creation of a (dye-sensitized) solar cell (DSSC). The introductory lessons guide students through activities covering volume, surface area and density and exploration of the relationship between these factors. The unit culminates with students building a Gratzel cell, a solar cell employing a layer of nanospheres of TiO2 as the semiconductor and blackberry juice as the light absorber in a non-Si-based solar cell. Students are able to build a small solar cell and test its efficiency.
Students in small groups conduct an investigation into the similarities and differences between solar tea and tea brewed by boiling water. Students will compare their two samples on four criteria—color, clarity, smell and taste—rate which they prefer, and graph the results of the experiment as a class.
You may have realized that the sun gives off heat. It feels so good to feel the warm sun on our skin when we're cold! The sun has an amazing amount of heat and even though we only get a small amount of that heat, it's just the right amount for us. You also may have realized how much light it provides us. Without the sun, we couldn't see. What about the moon? The moon doesn't have any light of its own. All of the light we see is really sunlight that is reflected or bounced off our moon.
Working in groups, students build simple solar stills filled with salt water and observe what happens when the stills are placed in the sun. The students then taste the water they have collected and discuss what has happened in their stills.
This module addresses issues dealing with the energy from the sun, the energy needs of students in the classroom and, ultimately, our energy needs as a nation. Students will use a photovoltaic (PV) cell to measure the energy from the sun. Using a light bulb with a known wattage, the students will illuminate the bulb using a PV cell. This way the students will know the approximate energy coming from the PV cell.
These nine projects allow students to set up their own investigations and manipulate the variables that influence photovoltaic cells. The projects can be easily integrated into a normal science classroom curriculum, or can be completed by students individually for science fair projects. All of the projects will fit easily into classroom lessons surrounding scientific inquiry and the scientific method. They will also help illustrate concepts in electricity, light and color, velocity and gravity, chemistry and polarity, and could even lead to social studies or social action projects.