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Teaching Solar Energy

Teaching Solar Energy. Energy From the Sun. Students understand that solar radiation is energy and does work. Solar Energy. Radiation: Energy transmitted as electromagnetic waves or as subatomic particles

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Teaching Solar Energy

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  1. Teaching Solar Energy

  2. Energy From the Sun Students understand that solar radiation is energy and does work.

  3. 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

  4. 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

  5. Assessing Solar Resource Students understand the concept of solar resource and that the energy available to us through solar radiation varies predictably.

  6. 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

  7. Solar Resource

  8. Incident angle

  9. 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.

  10. The Sun’s Path

  11. Solar Irradiance

  12. US Solar Resource

  13. Shading

  14. 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

  15. The Photovoltaic Effect Students are familiar with this terminology and understand that photovoltaic cells convert energy from the sun into a flow of electrons.

  16. 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.

  17. 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/

  18. Solar Circuits Students gain familiarity with photovoltaic technology and simultaneously reinforce their knowledge of energy principles.

  19. 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; [ P = 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 ]

  20. 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

  21. Series Wiring • Voltage adds in series • Current remains the same. • If you lose one load or one source you lose the series.

  22. PV Module Series Wiring

  23. Parallel Wiring • Current adds in parallel • Voltage is the same • If you lose one load or one module it doesn’t affect the others

  24. PV Parallel Wiring

  25. Series and Parallel Combination

  26. 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

  27. The Photovoltaic System Students learn about the componentry and design of a photovoltaic system.

  28. Tilt and Orientation Factor (TOF)

  29. 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%

  30. System Production Data Take from PV Watts, a tool developed by NREL

  31. Cell => Module => Array cell module String array

  32. PV System Components

  33. 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/)

  34. Viewing System Production Data www.solar4rschools.org

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