How Do Solar Lights Work?
Have You Ever Wondered...
- How do solar lights work?
- What are the main parts of a solar light?
- Do solar lights work better at certain times of the year?
Many years ago, the thought of powering lights by harnessing the power of the Sun sounded like science fiction. Today, though, you can see solar panels dotting the rooftops of buildings and houses, as well as street lights in some cities.
What was once a dream has become reality, In fact, you might even have solar power at your fingertips in the form of a solar-powered calculator. If you have a garden or landscaping at home, you might even have solar-powered lights guiding your path at night.
Have you ever stopped to WONDER exactly how these affordable solar lights convert the Sun's rays into electricity to power lights that shine for hours after the Sun goes down? Is it magic? Nope! It's science!
Solar lights work because of the photovoltaic effect. The most important part of a solar light is the photovoltaic or solar cell. The solar cell is the part that converts sunlight into direct electrical current. You can clearly see the solar cell as a dark panel at the top of a solar light.
A solar cell consists of multiple layers of crystalline silicone and chemicals that create layers of negatively-charged electrons and positively-charged spaces. As sunlight passes through the solar cell, it excites the negatively-charged electrons and pushes them into the positively-charged spaces.
The positively-charged spaces then transfer the electron stream as a direct current of electricity through wires embedded into the solar cell to a battery where the electricity is stored until it's needed. The battery charges throughout the day as sunlight continues to be converted to electricity.
When evening approaches, the solar cell stops converting sunlight as it weakens and eventually disappears. A photoreceptor on the light detects when it's dark and turns on the light, which is usually made up of several light-emitting diodes (LEDs). The battery then supplies electricity to the light throughout the night.
This process repeats on a daily cycle. During the day, sunlight is converted to electricity and stored in the battery. At night, the battery supplies the electricity to the light until it is all used up or the photoreceptor shuts off the light as daylight reappears.
Of course, adequate sunlight is necessary to charge the battery fully. During the summer, this shouldn't be a problem as long as the light is placed where it can receive direct sunlight for most of the day. If possible, make sure no trees or bushes create shade that could affect the charging of the solar light.
During the winter, however, a solar light might not be able to receive enough sunlight to charge the battery sufficiently to stay lit all night. This occurs because in winter nights are longer and days are shorter, resulting in fewer hours of sunlight to charge the battery. In addition, wintertime often brings snow, which can block the solar cell and prevent charging during the day.
Try It OutWe hope today's Wonder of the Day shined some light on solar power for you! Keep the learning going by checking out the following activities with a friend or family member:
Do you have any solar-powered lights around your house? Many people use solar-powered lights in their garden and landscaping. Check around your house to see if you have any of these items. If not, ask an adult friend or family member to take you on a quick field trip to a local store to check out their selection of solar-powered garden lights. How many different types can you find? How are they similar? How are they different?
Are any of the streets in your hometown powered by solar panels? What about any of the homes in your neighborhood? Ask an adult friend or family member to take you exploring around your city to see how many different examples of solar energy you can find. Keep a sharp eye out for solar panels on top of street lights and/or buildings and houses. How many examples of solar power do you see? Do you see more or fewer examples than you expected?
Up for a challenge? You're tasked with building a small community within an existing city. Your community will be powered solely by solar power. Where would you choose to locate your community? You can pick any city around the globe. Do some Internet research to determine what cities might best be suited for a solar-powered community based upon the average number of sunny days they experience each year. Are there any other factors you would consider? Where would you choose to build your solar-powered community? Share your thoughts with a friend or family member.