The amount of electricity a solar panel generates depends on several factors: the surface area, the efficiency of the cells, and the quality of the sunlight.

Photograph by Ruslan Dashinsky/Shutterstock

Usage Tips

  • Quality AND quantity matter. The quality of the sunlight has a large effect on the efficiency of solar cells. Bright, direct sunlight will provide a better charge than sun obscured by clouds or windows.
  • Check the current. PV cells generate direct current (DC), the same kind of current a battery provides. To power alternating current (AC) devices that are plugged directly into a wall outlet and don't usually contain batteries (like a lamp, for example), you need to buy an inverter that switches DC to AC. Some solar chargers can’t handle inverters, so be sure to check with the manufacturer before you use one.

« Environmental Impact


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The Great Energy Challenge

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    What Is It?

    An initiative to help you understand our current energy situation.

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    Personal Energy Meter

    See how you measure up against others, and how changes at home could do tons to protect the planet.

Step Up to the Challenge »

The World's Water

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    Help Save the Colorado River

    NG's new Change the Course campaign launches. When individuals pledge to use less water in their own lives, our partners carry out restoration work in the Colorado River Basin.

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    Water Grabbers: A Global Rush on Freshwater

    A special series on how grabbing water from poor people and future generations threatens global food security, environmental sustainability, and local cultures.

Learn More About Freshwater »