Solar Cell Efficiency
Solar Cell Efficiency is how much of the sunlight hitting a solar cell gets turned into electricity.
Pour 10 cups of water onto a flat tray from above. Only 2 cups land in the small bowl placed in the center — the rest spills and is lost. That bowl holds just 20 percent of what you poured. A solar cell works the same way: light falls on it, but only a small part turns into power.
Explaining solar cell efficiency by grade level
A solar cell does not use all the light it gets. Some light turns into power. Some just makes heat. Tipping the cell to face the sun helps it work better.
Projects that explore solar cell efficiency
Heat changes how much light a solar cell turns into power. You investigate by exposing a solar cell to different temperatures and measuring the voltage in millivolts, the current in milliamps, and the power in watts. The power is higher at lower temperatures.
The angle of the sun's rays changes how much power a solar cell produces. You mount the cell on a board, then move the board to different angles with the sun and measure the voltage going to the cell. When the cell sits perpendicular to the sun's rays, the power going to the cell is maximized.
How much sunlight reaches the cell's surface determines how much power it produces. A parabolic dish lined with aluminum foil and a flat mirror each concentrate sunlight onto a solar panel in different ways, boosting the light available for conversion. When you measure the voltage and current with each reflector, the parabolic reflector produces the highest power output, followed by the flat mirror.
When sunlight hits a panel straight on versus at a steep slant, the energy output shifts. You mount seven identical solar cells on wooden blocks cut to different angles and measure the voltage and current from each at noon on a clear day. The cell aimed straight at the sun produces the most power, and output drops steadily as the angle moves away from perpendicular.
Solar cell efficiency — how much sunlight gets turned into electricity — drops when cells overheat. On a sunny day, a solar panel heats up quickly, and that rising temperature may lower its electrical output. The fan-cooled cell produces the most power, while the cell on the hot metal plate produces the least, showing how thermal management affects efficiency.