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How do Solar Lights Work?

Arun Prabhu Feb 28, 2019
As one of the smaller steps to reducing the carbon footprint on an individual level, the solar light is definitely a good thing. They range from impossibly cheap to unexpectedly costly, from a one month purchase to a lifetimes worth of an investment, the solar light is here to reduce your electricity bill.
The solar light comes in many shapes and sizes, colors and brightness. What makes the solar light unique is that you will never need to supply any electricity to it. The light will remain self-satisfied on that front. All you need is a place that gets enough sunlight through the day and about a minute of your time to install the light.

Parts of a Solar Light

The insides of a solar light are pretty easy to figure out. The light is the same as a regular light that will come with battery contacts, a bulb and a switch. Same goes for the solar light, but with a few changes.
◈ Instead of a regular battery, you have a rechargeable AA NiCad battery(most of the time). To charge the battery, you use solar light.
◈ The sunlight is harnessed using a photo-voltaic cell mounted on top of the light. When you install the light, you need to make sure that this part comes in direct contact with sunlight.
◈ A bulb in most cases would be an LED source. They are cheap, durable and just the right fit for such a low voltage operation.

◈ The switch in a solar light would be a photoresistor. It's a sensor that can detect light falling on it and reacts accordingly.
◈ A small set of controllers to regulate the voltage and current in the circuit.

◈ All in all, after you finish installing the light, the only other time you need to look at it again is when you repair the light or replace it.

Solar Lamp Working

Generating Electricity

The first step to making the lamp glow is to generate electricity. That's the light cell's job. During the day, the sunlight hits the photo-voltaic cell, which generates the electricity and stores it in the battery.
Now, a single photo-voltaic cell makes about 0.45 volts and a current according to its size. An ordinary solar lamp has four of these, which means you get around 1.8 volts that carries whatever current produced throughout the day.

Producing Light

The solar light is unique in the sense that it doesn't need to be switched on manually. It switches on automatically when there is little or no light falling on the lamp, like in the evening. This is done with the help of a photo-resistor. The battery is connected to the LED through the controllers and the photo-resistor.
The photo-resistor is nothing but a sensor that needs sunlight to stay open. When there is little or no sunlight, the photo-resistor shuts off and closes the circuit. This means the wires connecting the battery to the LED have a clear path, turning the LED on.

How the Cell Makes Electricity

The cell is covered by a non-reflecting protective covering. Underneath the covering are two layers, one with negative electrons and the other with positive holes.
When sunlight falls on the cell, the negative electrons are released into the positive holes due to the voltage difference created between the two layers. And so, the electrons flow and you get electricity flowing through to charge the battery.

Solar Lamp Facts

The battery, if one of quality, can last for two years.
You will need to clean the contacts sometime to remove the rust and dirt that can block the contacts. A fully charged battery can supply power to the LED for about fifteen hours. If you want a solar lamp for indoor lighting, you can also buy the solar lamp that has an extension wire between the cell and the light.
Solar lamps come in a variety of shapes and sizes, so they can create more ambiance and be less of an eyesore than you think.
Using a solar lamp is a great way to say goodbye to extra wiring, extra maintenance and large light bills. It proves to be a small step that you take to help save fossil fuels for later use. They were a lot costlier 10 years ago and they will be cheaper 10 years from now, but the need of the hour is to conserve, so do your part for earth.