Teaching Solar Energy
SLIDE 1
Energy From the Sun
Students understand that solar radiation is
energy and does work.
SLIDE 2
Solar Energy
• Radiation: Energy transmitted as electromagnetic
waves or as subatomic particles
• We experience solar energy as light and heat, and
the simplest way for humans to capture and utilize
this energy is through passive solar technologies
» Solar cooking
» Building design
» Greenhouses
» Solar hot water
SLIDE 3
In the Classroom
Demonstration: Global Sun Oven
» Reaches temperatures in the mid- to upper-300°Fs
» Exemplifies all the principles of solar cooking
Activity: Students Build Their Own Solar Ovens
» For younger students there are a number of pre-existing
solar oven designs
» Older students can design their own ovens
Other Resources:
» www.solarcookers.org
» www.solarcooking.wikia.com
» www.sunoven.com
SLIDE 4
Assessing Solar Resource
Students understand the concept of solar
resource and that the energy available to
us through solar radiation varies
predictably.
SLIDE 5
Measuring the Sun’s Energy
• Irradiance: the amount of power received from the
sun over a given area of earth
» Typically measured in Watts per Square-Meter
• Cumulative Irradiance: the amount of energy that
hits an area over a certain period of time
» Typically measured in Watt-Hours per Square-Meter
SLIDE 6
Solar Resource
SLIDE 7
Incident angle
SLIDE 8
Effects of Atmosphere
• The lower the angle of the Sun in the sky, the more atmosphere
the Sun’s rays must pass through to reach earth and therefore the
less energy those rays have when they reach earth.
SLIDE 9
The Sun’s Path
SLIDE 10
Solar Irradiance
SLIDE 11
US Solar Resource
SLIDE 12
Shading
SLIDE 13
In the Classroom
Activity: The Reasons for the Seasons
» The first section in “Teaching Solar” explores the
concept of solar resource, the predictability of the Sun’s
position in the sky, and begins to go into sun charts
Activity: Sun Charts
» On the Solar 4R Schools website, there is a worksheet
activity available for download
Demonstration or Activity: Solar Pathfinder
» Using the Solar Pathfinder to do a shading analysis of a
site
SLIDE 14
The Photovoltaic Effect
Students are familiar with this terminology
and understand that photovoltaic cells
convert energy from the sun into a flow of
electrons.
SLIDE 15
The Photovoltaic Effect
• Definition: The creation of a voltage (or of a corresponding
current) in a material upon exposure to electromagnetic
radiation.
» Exposure to light generates a voltage that produces a continuous
current flow, which is proportional to the quantity of light that strikes
the photovoltaic surface.
» In PV technology, one cell – regardless of size – always generates
0.5 V; size difference impacts the amount of current generated,
thereby affecting power production.
SLIDE 16
In the Classroom
Activity: Powering a Load with a Solar Cell
» Using materials from the SolRun kit, students can wire the 1.5V cells to
motors with fans, LED lights, small radios or other small loads
Activity: Solar Racing
» Using the SolRun kit, students can build solar cars
Activity: Testing Voltage and Current with Solar Cells
» Using multimeters, students can test the voltage and current of the solar
cells under different light conditions
Other Resources:
» phet.colorado.edu/en/simulation/photoelectric
» http://www.pveducation.org/
SLIDE 17
Solar Circuits
Students gain familiarity with photovoltaic
technology and simultaneously reinforce
their knowledge of energy principles.
SLIDE 18
Terms and Definitions
• Voltage (V): electrical potential difference
• Measured in Volts, voltage is the work required to move a unit of charge
between two points against an electric field
• Current (I): rate of electrical flow
• Measured in Amps, current is the amount of electrical charge
transferred per unit of time
• Power (P): rate at which work is performed
• Measured in Watts, power is the product of current and voltage;
= VI ]
• Energy (E): work performed over time
• Measured in Watt-hours, energy is the ability of a system to do work
and is the product of power and time; [ E = Pt ]
SLIDE 19
[P
Terms and Definitions (cont.)
• Alternating Current (AC): an electrical current, which periodically
reverses direction
• Our electrical grid operates on AC electricity
• Direct Current (DC): an electrical current, which moves in a single
direction
• Batteries and photovoltaic (solar-electric) cells both produce DC
electricity
SLIDE 20
Series Wiring
• Voltage adds in series
• Current remains the same.
• If you lose one load or one
source you lose the series.
SLIDE 21
PV Module Series Wiring
SLIDE 22
Parallel Wiring
• Current adds in
parallel
• Voltage is the same
• If you lose one load
or one module it
doesn’t affect the
others
SLIDE 23
PV Parallel Wiring
SLIDE 24
Series and Parallel Combination
SLIDE 25
In the Classroom
Activity: Wiring Solar Circuits
» Students can wire together series and parallel circuits using
the solar cells. Ultimately, these circuits can be built to run
larger loads.
Activity: Circuit Modeling
» phet.colorado.edu/en/simulation/circuit-construction-kit-dc
» LTspice IV (www.linear.com/designtools/software)
Other Resources:
» Teaching Solar Book & DVD
SLIDE 26
The Photovoltaic System
Students learn about the componentry and
design of a photovoltaic system.
SLIDE 27
Tilt and Orientation Factor (TOF)
SLIDE 28
Total Solar Resource Fraction
(TSRF)
• Total Solar Resource Fraction = percentage of
the potential solar resource that a photovoltaic
system is able to harness
• TSRF = (100% - % Shading) x (TOF)
• TSRF = (100% - 5%) x (91%)
• TSRF = 86.45%
SLIDE 29
System Production Data
Take from PV Watts, a tool developed by NREL
SLIDE 30
Cell => Module => Array
cell
module
array
SLIDE 31
String
PV System Components
SLIDE 32
In the Classroom
Activity: Designing a Photovoltaic System
» Using the Pathfinder, an understanding of basic PV system
componentry and design and the resources below, students can
design a solar-electric system for their home. Based on their electrical
bills, they can match expected system production to their
consumption.
Other Resources:
» Photovoltaic Systems book
» PVWatts (mapserve3.nrel.gov/pvwatts_viewer/index.html)
» pvselect.com
» System Advisor Model (https://sam.nrel.gov/)
SLIDE 33
Viewing System Production Data
www.solar4rschools.org
SLIDE 34