The Science of Solar Lights

Many years ago, the thought of powering lights by using the power of the sun sounded like science fiction. Today you can see solar panels on a lot of rooftops of buildings and houses, as well as street lights in some cities.

What was once a dream has become a reality. You may have solar power at your fingertips already and never realized it. Like maybe a solar powered calculator. If you have a garden or landscaping at home, you might even have solar-powered lights guiding your walkway at night

Have you  ever wondered exactly how these affordable solar lights convert the sun’s rays into current to power lights that shine for hours after the sun goes down? Nope its not magic, its 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 converts sunlight into direct current. You can clearly see the solar cell as a dark panel at the top of a solar light.

A solar cell is made up of several layers of crystalline silicone and chemicals that create layers of negatively-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 through wires embedded into the solar cell to a battery where the current is stored until it is needed. The battery charges throughout the day as sunlight continues to be converted to current. When evening approaches, the solar cell stops converting sunlight as it weakens and eventually disappears. A photoreceptor on the light detects when its dark and turns on the light, which is usually made up of several light-emitting diodes (LEDs). The battery then supplies current to the light throughout the night.

This process repeats on a daily basis. During the day, sunlight is converted to current and stored in the battery. At night, the battery supplies the current to the light until it is 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 other landscape shades the sun from the solar cell so as to not affect the lights charging capabilities.

During the winter months, however, a solar light may not be able to receive enough sunlight to charge the battery sufficiently to stay lit all night. This occurs because in winter the nights are longer and the days are shorter, resulting in fewer hours of sunlight to charge the battery. Sometimes winter often brings along snow and ice, which can block the solar cell and prevent charging during the daylight hours.

I hope you enjoyed this little tutorial on solar lighting.  Thanks for reading.  Mike Cox