Let the Sun Shine!
Solar panel reflecting sunCopyright Flickr https://www.flickr.com/photos/atc_euroenergy/4364587067/in/photolist-7DFDFa-fLPte3-8v4vzw-rUx7cU-azwqXW-jp9ApD-sM8zui-s5x5PC-AmD1D6-GqbDys-qP218U-7H911c-wKAS6K-dk23dZ-8qdBL9-7vzTKC-s9UaRY-iKy29D-a3bzKo-HAHDsA-bEMCPC-xzbkZs-rEtWwz-bWWEwF-gKJbby-wDaQNE-dch4KR-suBMos-aXSqta-pBJ5yF-bTGwmr-gR1ms2-dvrWkP-fvpBhy-apiVSp-f6tRoy-avo2TF-apiWuP-KHHvCb-dk24PJ-a1P1ga-5CW6qN-8xkoFc-rnGaJo-NwbSM4-r9dyY2-6mHa9X-8bp3rk-6zNdU8-BJBnBL
Students learn how the sun can be used for energy. They learn about passive solar heating, lighting and cooking, and active solar engineering technologies (such as photovoltaic arrays and concentrating mirrors) that generate electricity. Students investigate the thermal energy storage capacities of test materials. They learn about radiation and convection as they build a model solar water heater and determine how much it can heat water in a given amount of time. In another activity, students build and compare the performance of four solar cooker designs. In an associated literacy activity, students investigate how people live "off the grid" using solar power.
Engineers who design spacecraft or satellite components know that white objects reflect the sun and stay cooler, while objects painted dark colors absorb heat and stay warmer. This is important when objects pass through the sun's shadow while orbiting Earth. Space shuttles are white on top and dark on the bottom, and components that need to remain heated are located at the bottom of the shuttle. For everyday use, engineers are designing a paint that diffuses energy and stays cool, which could serve as a heat shield in many applications since dark colors absorb enough solar heat to sometimes send surface temperature to 190 °F on a sunny day. The black still looks black, because the paint absorbs light normally across the visible spectrum, but special pigments with bits of inorganic metals reflect the infrared light, effectively turning away half of the sun's energy.
After this lesson, students should be able to:
- Differentiate solar energy as being either active or passive.
- Describe how energy can be transformed from solar energy to electrical energy.
- Explain how the sun's position changes the amount of solar energy that can be concentrated and stored.
- Explain how engineers work with solar energy and why they need to know the sun's position.