How a Solar Light Works

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Courtesy of Greenshine New Energy LLC

A solar light is a light that has the ability to convert sunlight from the afternoon hours into electrical energy that eventually powers the light whenever it is required. It looks no different from a regular light but there are very many subtle differences in the background.

A solar panel collects the sun’s radiation and then transforms it into electrical energy. The converted electrical energy is then stored in rechargeable batteries that eventually power the light. The solar panel lasts for a very long time, about ten years or more, because it is made of a durable material but regular maintenance is advised. It may collect dirt and dust over time which may reduce the efficiency of the panel but regular cleaning will help with this.

It is usually located within the solar light but in some other instances like with solar outdoor lighting the panel and the battery are connected together with a thin wire to allow the panel to effectively collect sunlight.   

The battery is rechargeable and should be made of a quality type of material. With constant temperature fluctuations the battery can easily get damaged but a material that is resistant to such will increase the length and efficiency of the battery.

Types of batteries used

The number of batteries required in a solar light is dependent on the light itself but they are usually between one and four. The AA size made from Nickel Cadmium (NiCad)1.2V/500 to 900mA or the same size made from Nickel Metal Hydride (NiMH) 1.2V/1000 to 2000mA are the most commonly used but adjustments can be made for lights that need more powerful batteries.

Between the two mentioned above, the Nickel-metal hydride batteries will last much longer because they have almost threetimes the capacity of the Nickel Cadmium. They are also more expensive, can withstand a wide range of temperature fluctuations (between -20 and 60 degrees Celsius) and they are environmentally friendly since they are made of a dry liquid which makes disposing them much easier.

NiMH batteries are able to continue charging even on cloudy days due to a property known as ‘non-memory effect’. The fact that the batteries were partially charged during the cloudy days will not damage the battery, thus diminishing its performance. This is a common predicament with lead acid batteries and their efficiency would be drastically reduced within a short time.


The controller on a solar light does a number of functions. It may protect the rechargeable batteries from overcharging when sunlight is in plenty and the most common use is dimming the lights as required. In the case of solar street lighting the controller can dim the lights when traffic is minimal such as late at night and have them bright when there are a lot of people moving about like in the early evening and morning. It can even completely switch off the light when sunlight is bright enough to illuminate pathways and streets.

Solar lighting may require the sun to function but with proper adjustments and additions, they can continue lighting up streets and homes even when there is more cloud cover than sunlight.   

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