Exploring Solar Energy, Photovoltaic Cells, Electricity, Storage
Batteries, Motors, Generators and How They All Come Together To Do Work
that Comfort Our Lives
By
making actual voltage measurements and observing the resultant motion, this
science project reinforces tutorial web links to make this a fun learning
experience. This science project provides a strong emphasis on discovery that
will encourage students to explore concepts of solar energy, electrical power
production and it's conversion to other forms of energy.
This project consists of a combination of excellent website
tutorials and exercises that measure and compute power using an actual hardware
kit. The kit provides a hands on approach to learning power conversion
technique and theory.
Tutorials explain the physics of converting solar energy to
electrical energy and how electric motors work. The conversion
of electrical energy to mechanical energy and the conversion of mechanical
back to electrical energy are also explained.
Students use their own voltmeter to make electrical measurements
on project hardware during power measurement exercises to reinforce
website tutorials.
This project points to website tutorials on Motors, Generators,
Batteries, Solar Energy, Photovoltaic, and how solar energy irradiates
earth. Solar Tutorials are available here and here
The hardware is divided into five function groups:
1. Power source (Solar cell array). Solar panels produce electricity that either operate a DC motor, or charge batteries.
2. Power storage (Batteries). The motor operates from electricity generated
by solar cells or from electricity stored in batteries.
3. Switching function (Electric switches). A double pole, double throw (DPDT) switch selects the option to either run the motor, or
to charge the batteries. A single pole,
double throw (SPDT) switch selects the power source
(solar cells or batteries).
4. Energy conversion (Motor/Generator
assembly). The shaft of the motor is
connected to the shaft of a second motor that operates as a generator. This demonstrates the conversion of
electrical energy to mechanical energy (motor), then the conversion from
mechanical energy back to electrical energy (generator).
5. Work demonstration (Windmill kit). The generator produces electricity to run a
third motor that turns a propeller made to look like a working windmill.
Actually, the work produced is the propeller moving air.
Proper
characterization or testing of photovoltaic cells is crucial for determining
cell performance. A solar cell’s current
vs. voltage (IV) performance curve provide a simple to obtain yet important
parameter. IV Curves
An electric motor’s
power characteristics provide knowledge of the motors power requirements and
efficiency. While the electrical
parameters are relatively simple to acquire, the mechanical parameters (torque
and speed) require special tools to obtain.
Torque and Speed.
analysis of permanent magnet DC motors
and understanding DC motor characteristics
The
Scientific Method:
1. Define the
Problem
2. Hypothesis
3. Research (If you
purchase the kit, we supply just about all the research material you need via
internet websites.)
4. Test or
Experiment
5. Check
Hypothesis
6. Conclusion
A good tutorial on electric circuits and mechanical power is
located here:
The use of batteries to store solar power requires knowledge of how
batteries work. Batteries require maintenance, and caution because they are
toxic. The use of batteries is not an elegant method of power storage, but
there are a number of promising mechanical and Hydrogen storage techniques being
developed. Here are some web sites where you can learn of alternate forms
of power storage:
http://sites.netscape.net/dickfradellausa/basics.htm
http://www.solar-h.com/introduction1.html
hydrogen cars
To enhance the
learning process, understanding and interest, the following ideas were
incorporated:
1. Knife switches are used to aid the
visualization of the switching process and to enhance
the appearance of the model.
2. To
visualize the mechanical coupling between the motor and the generator, the motor is coupled to the
generator using plastic sprockets and chain link. This accentuates the motion aspect to
illustrate the power conversion sequence.
3. The
generator produces electricity that powers another motor mounted on a pole with a red propeller fitted
over it's shaft. This illustrates the fact that the generator generates electricity
to do work (Move air).
Exercise 1: Power Measurement
Exercise 2: Battery Maintenance
Exercise 3: Energy Conversion
The
prices for the kit are:
Totally
unassembled kit: $153.00
Partially assembled kit: $163.00
Fully assembled kit: $183.00
In order
to minimize shipping damage the fully assembled kit is disassembled, but can be
reassembled in a short time.
Price
includes US Postal Service ground shipping and handling.
Buyer
needs to have the following items for the totally unassembled kit: (These items
are not included in the kit)
Digital
Voltmeter
Soldering Iron and solder
Standard slot screwdriver
Wire cutter and stripper
Small hand drill or Dremel tool
Epoxy, Epoxy Putty or a
Hot Melt Glue Gun
Time and Patience
The following hardware is provided in the
kit:
- Three permanent magnet DC
motors (One motor works as a generator)
- Eight 0.45 Volts @ 0.4 Amps solar cells
- One single pole, double
throw knife switch
- One double pole, double
throw knife switch
- Wire and wood screws
- Three current measuring
resistors - 0.1 Ohm @ 1%
- An 8 in. x 8 in. x 0.5
in. varnished birch plywood base
- One 0.75 in. x 0.75 in. x
3 in. wooden motor mount base
- Wooden solar cell
mounting supports - Solar cells mounted directly on Plexiglas
- Two D size Nickel Cadmium
rechargeable battery cells (Panasonic Model number P-400DH) Battery Specifications
- One battery holder that
holds 2 D size rechargeable batteries
- One 0.25 in. diameter x 3
in. long windmill mounting pole
- One windmill blade
- Two IN914 diodes
- One 2 position terminal
- Two sprockets (Material:
Dupont Delrin 500)
- One drive chain
- One 5.5 in. x 7 in. x
.093 in. Plexiglas
sheet
- URL of Web
page with active links of tutorials, exercises and assembly instruction
For indoors demonstration of the Solar Energy
Science Project, two 90 Watts Halogen flood lamps can be used to make this kit
work. These two Halogen lamps are 24
inches away from the solar cell array.
Disclaimer: This is a solar energy science kit, as
such it is designed to work from solar energy.
It may not work using home lighting.
The energy content of a 100 Watt light bulb is not sufficient to operate
this kit. It may operate using the
appropriate Halogen flood lamps, but care should be taken when working with 120
Volt AC line power. As the picture above
shows, two 90 Watt Halogen flood lamps can make this kit work. The flood lamps are 24 inches away from the
solar cell array. Ninety Watt flood
lamps generate a great amount of heat; care must be taken not to place the
flood lamps too close to the array or the heat could melt the solar cells. We are not responsible for any accident or
death resulting from attempts to make this project work with line power.
An excellent web tutorial on
radiant light energy is provided by International Light.
Your comments about this web page are
most welcome. I build these kits at home and ship them from home. Please
indicate how you learned of this web site.
If interested please contact me at the following number:
Contact Ed Avilez at
520 663-1290 or Pager: 520 489-2946
or
Email me at: apptechy@earthlink.net
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