Solar Energy
Solar Energy is light and heat from the sun that we can capture and use.
A dark flat tray sits in a sunny window. The sun's rays fall on the tray and warm it up, storing heat inside it. You can pull that stored heat out by placing a cold bowl on top — the tray heats the bowl. Solar power works the same way: the sun sends out free heat and light, and we use panels to catch it.
Explaining solar energy by grade level
The sun sends light and heat to Earth every day. A black bottle in the sun gets hot fast. We can use that heat to warm water or cook food. We can also turn sunlight into power.
Projects that explore solar energy
A solar cell captures light from the sun and turns it into power — voltage, current, and watts you can measure. Temperature affects how much the cell generates. Higher temperatures tend to reduce the voltage and current, while lower temperatures produce more power.
How you aim a solar cell at the sun changes how much power it captures. You mount the cell on a board, move the board to different angles with the sun, and measure the voltage going to the cell at each position. When the cell faces the sun straight on, the power going to the cell is maximized.
Sunlight can be concentrated to reach extreme temperatures. A solar furnace bounces light from many mirrors onto a single point, and the more mirrors you add, the hotter the focal spot becomes. A large enough array can generate temperatures high enough to melt steel.
Reflectors help capture more sunlight by redirecting rays that would otherwise miss the cell. A parabolic dish lined with aluminum foil and a flat mirror each concentrate sunlight onto a solar panel in different ways. Using parabolic mirrors helps achieve the highest level of photovoltaic output from solar cells.
The sun sends light and heat to Earth. That light can change things it hits. Paper changes color where it is exposed to sunlight.