Solar lights are essentially small power systems that collect energy from the sun and convert it into lighting. During the day, sunlight is converted to electricity and stored in a battery. At night, the battery supplies the electricity to the light (usually LED) until it is all used up or the photoreceptor shuts off as daylight reappears.
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Solar lights contain several components: a solar cell, a rechargeable battery, a LED light and a photoreceptor. All these components are mounted to work as a single unit that collect, store energy and convert it into lighting. You can usually see the solar cell as a darkpanel at the top of a solarlight. The solar cell collects energy from the sun, converts it into electricity throughout the day and charges the battery. This is done through what is known as the photovoltaic (PV) effect, a process that generates voltage or electric current in a photovoltaic/solar cell when it is exposed to sunlight (Source: https://energyeducation.ca).
When evening approaches, the solarcell stops converting sunlight as it weakens and then disappears. A photoreceptor detects when it's dark and turns on the light, which is usually made up of light-emitting diodes (LEDs). The battery then supplies electricity to the light throughout the night. This process repeats on a daily cycle.
Because solar lights are powered by the sun, they should be placed in an area that receives full sun (ideally eight or more hours per day). In some cases you don’t even necessarily need direct sunlight. Some solar devices will take energy indirectly and use it to work. Besides providing some good aesthetic to outdoors, solar lights are very easy to install, no need of wires, are low maintenance and will provide you illumination without costing you any money on energy.
To help you visualize the power of solar lighting we share below a promo video: