Session Four: Energy, Electricity, and Solar Power Systems

Materials:
Kill a watt meter
Sun path models
Large solar panel
Mini solar panels

Lesson Components:
Energy
Electricity
Energy Conservation and watts
Our relationship with the Sun
How Solar panels produce energy

Personal Research Panels!!
Site analysis for solar PV systems

Energy

We began class indoors in the great room. Nate wrote the word "Energy" on the whiteboard, and asked the class for some examples of energy. The students gave all kinds of answers, from coal, wind, solar, nuclear, oil and natural gas. Nate asked the class to divide those types of energy into renewable and non renewable, which they did without problems. Then Nate wrote down a simple definition of energy as "the ability to do work". He explained that energy represents the ability to do all types of work, whether its powering a motor, sending electricity to a light bulb, or even shoot a basketball at recess. All this "work" requires energy, and that energy can come in many different forms. He told the class that all of the non renewable, fossil fuels that we use to power our homes and cars, where actually "ancient sunlight", plants and organic matter that had decomposed and fossilized over millions of years. The students thought that was very amusing.

Electricity (Electrons in Motion)

Getting more specific and practical, Nate began talking about the energy we use in our homes, to power our lights, electrical outlets, and refrigerators. In our homes, we use electrical circuits to channel and deliver electricity to the devices and machines that need them. And all electricity is simply "electrons in motion". Several students were familiar with electrons, protons and neutrons, and this was helpful. It was great to see a lot of "light bulbs going off" when the students realized the connection between electrons and electricity.

Energy Conservation - The kill a watt meter

Nate went on to revisit and discuss with the class that most of the energy we use in our homes come from fossil fuels, and those are all finite resources. If we are going to get serious about replacing fossil fuels with renewable energy, the best place to start is with energy conservation, which is simply using less electricity in home, work or school.

A researcher displaying the kill-o-watt meter

Students calculating the energy usage of a household fan

Testing the combined wattage of the class laptops

Our relationship with the sun
Fundamental to understanding solar technology, is an understanding of our relationship with the sun. All of life on earth depends upon the sun. Nate began by telling the students that the sun has a dependable path that we can follow every day, but that path varies depending on the date/month of the year. The one constant is that the sun rises in the east and sets in the west. Nate had the students demonstrate this by holding signs that said "east" and "west". To illustrate how the sun moves throughout the sky during the year, Nate had volunteers mimic the sun's varying path from east to west for both the winter and the summer months. In the winter, the sun is lower in the sky, which results in less daylight hours, and "shorter" days. In the summer, the sun is high in the sky, so we have more hours of daylight, and "longer" days.

low winter sun

high summer sun

The sun's path is very important when it comes to Solar panels. In order to maximize the amount of energy we can produce, we want to angle and tilt our panels to match the sun's path at different times of the year


How solar panels produce energy
Next, Nate demonstrated the process by which solar panels produce electricity. He began by illustrating the main components of a solar panel, and used the analogy of a sandwich. Essentially, a solar panel is like a sandwich made of of two types of silicone; n-type and p-type. When sunlight (photons) hit the panel, it sets in motion a chemical reaction of electrons flowing between the two types of silicone. The key part is that we can direct those flowing electrons into useful work, like powering our lights, appliances and other energy needs, or store them in a battery to be used later.

Solar panels and their orientation to the sun
Utilizing the students as contextual models, Nate demonstrated how solar panels should be tilted forward in the winter, and angled flat on their back during the summer. Again, this is because the sun is lower in the sky during winter, and directly overhead in the summertime.

winter - the sun is low, panels are
tilted up and forward

Summer - Sun is high, panels are tiled back and flat

Student with 100watt demonstration panel

Personal Research Panels

With a solid foundation build on the basics of solar photovoltaics, it was time to make a fun announcement. Nate had asked the class in a previous session if they would like to help him conduct research into solar panels and the poke weed plant. Today we told the class that they would all be receiving their own personal, mini solar panels to use in the research. Everyone was very excited, and spent some time making observations of their panels. Our research will continue with the personal research panels next week.

Site analysis for solar PV systems
With all these new ideas and knowledge about the suns' path and maximizing solar panel efficiency, it was best to go outside and do some solar site evaluation for the school property. Nate led the group outside and had the students identify ideal spots for solar panel array placement. Coincidentally, the same aspects that make a location good for a garden (south facing, no shade) are the same characteristics we are looking for in a good solar panel site. The students toured the entire school grounds, and identified 5 ideal locations for solar panel installations, including the school's south facing roof.









Nate and students do
solar site analysis at the school, finding different locations for solar panel installations.

Session Three: Science Solves Problems

Materials

White board and class discussion

Topics covered
Science is....
The ingredients of science
Science Solves Problems - Applied Science

This was a short 1/2 hour lesson that Nate facilitated with the class at Summer's Knoll. The purpose was to build upon the problem based permaculture foundation that we have created, and begin to integrate the scientific method, or what is known as "applied science".

Nate began by writing "SCIENCE" on the white board, and asked the class to offer their personal definitions of science. Several themes emerged, most notably, that science was a way to discover and understand the world around us. After the discussion, Nate proposed a concrete definition of Science:

"Science is a recipe for solving problems. Science Solves Problems (SSP)".

Nate explained further, that just like any other recipe, their are ingredients to Science. The ingredients are added in a specific order, so that we can get the desired result, and solve our problem. Nate then went through the ingredients of Science with the class.

1. Observation
- Just like in Permaculture Design, Science starts with observation. This is where we identify that there is in fact a problem. Once we have observed what the problem is, we can start to collect all the parts and pieces involved in the problem. These are the Variables. Once we have identified all of the variables, we can finally start to think about how we will Measure them (by amount, or over time, or both)

We used a practical example to illustrate this. Nate told the class to imagine that they were in their homes, when all of a sudden they start to feel water drops on their heads. In this example, we observe that there is water falling from the ceiling. We might then observe that it is raining outside. So the variables are, the ceiling, the water drops falling inside, and the rain falling outside. We could then start to think about ways to measure the variables. Like how much rain is falling outside (inches per hour), how big the hole is in the ceiling, and how much water is falling from the ceiling.

2. Hypothesis
Many students had heard the word Hypothesis before, but to create a better picture of what it means, Nate told the class that it was an explanation based on observations. To illustrate this further, we used our simple example to construct a hypothesis. Based on observing, we concluded that there must be a hole somewhere in the roof, allowing rainwater into the house, which was leaking down onto our heads.

3. Prediction

After we explained hypothesis, the next ingredient is to make a prediction based on some type of change or experiment. Nate explained this by offering several hypothetical experiments that we could try in our rainy roof scenario. The simplest being that if we followed the water trail up through the floor boards and ceiling, to the roof, we could located exactly where the leak was coming into the house. The prediction we could make, was that if we plugged the leak in the roof, the water coming into the kitchen would stop.

4. Experiment

Finally, the last ingredient in science was the experiment, when we get to test our hypothesis and find out if our predictions were right or wrong. Nate illustrated to the class that being wrong, or having a prediction be incorrect was an important part of science solving problems, because these are the opportunities to think differently and learn new knowledge. He emphasized that we can always go back and try the ingredients in order again, but with different hypotheses and predictions based on our previous work.

This session was a good way to introduce and use analogy in applied science education. By giving the example of the leaky roof, it was an hypothetical analogy of a real world problem that science could help solve. The use of analogy is very important in developing self directed learning (SDL) skills. In problem solving, students that can think of similar situations where problems have been solved have a wider range of experiences to draw up hypotheses and predictions from. This facilitates and encourages critical thinking, and the ever so desirable "outside the box" mentality that successful engineers and scientists are able to utilize when designing innovations.