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How Do Solar Watches Work? Find Out The Facts

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Tim Rhodes

How do solar watches work? It’s one question you’ll ponder on if you just hear of the existence of solar watches.

The energy derived from the sun is referred to as solar energy.

Technology has found a way to harness a bit of that energy and use it to power timepieces.

You know about different types of watches, and now there is a buzz about solar-powered watches or solar watches.

You are used to the wide-area surfaced panels, so you are thinking, how did they manage to fit one in a small watch, that would be enough to power it?

That’s the essence of this article, as it covers what Eco-Drive Technology is, the mechanism of watches, popular companies that have solar watches among their series, as well as the pros, and cons of a solar watch.

Find Out How Solar Watches Work

This article will also discuss the best solar watches, according to professional reviews, and the types of movements made by watches.

Eco-Drive Technology

Eco-drive technology is the process of converting light to energy and storing that energy in a power cell.

Imagine having a device that you never have to worry about recharging, or replacing the battery for years, awesome!

Eco-drive technology makes it possible, as long as there is light or sunlight, any of your devices, in this case, a wristwatch, will always be charged.

These solar-powered watches were not invented to utilize only sunlight as a power source.

They also have a feature which is atomic timekeeping, which means they receive radio signals from atomic clocks, to set the time correctly.

Atomic Clocks:

Atomic clocks are the most accurate clocks across the world.

Eco-drive watches use a rechargeable lithium-ion, powered by the light energy trapped by the small solar panel, behind the dial.

The rechargeable Lithium-ion battery is not the only type of Eco-drive watches that exist, one of the types uses temperature difference as a power source.

Thermo Eco-Drive watches have exploited the disparity between the temperature of the wearer’s skin, and ambient temperature to recharge the battery.

The Eco-drive Thermo watch uses a Seebeck Effect, to generate thermoelectricity, that powers the electronic movement and charges the secondary power cell.

The Hybrid Eco-drive watches combine mechanical power and the solar cell, to control the movement and the secondary cell.

There is the Citizen Vitality series from Citizen, that used the watch hands to drive a small electric generator, but following complaints that the device could explode and cause wrist injuries, Citizen discontinued it.

For this article, we will focus on Eco-drive watches, powered by solar energy or light.

Citizen Watch is a timepiece making company, based in Tokyo.

This company is known as the pioneer, for Eco-drive watch.

The Mechanism of Watches

Watches have three major movements they can make.

They are the quartz movement, the mechanical movement, and the automatic movement.

These movements are what makes a watch tick, or simply put, it is what moves the hands of a watch.

The Quartz Movement:

First, quartz is a chemical compound or a type of crystal formed from silicon dioxide.

This chemical compound has a unique attribute, called the piezoelectric effect.

Piezoelectricity means, electricity resulting from pressure and latent heat.

Piezoelectric effect means electricity can accumulate in this crystal, when subjected to mechanical stress, such as bending across some planes or exposure to heat.

Likewise, this crystal is driven by electricity, when charges pass through them.

The quartz movement of a watch, simply refers to the hands of a watch powered by electricity, usually from a battery.

A Japanese company called Seiko first invented the quartz watch.

How Quartz Movement Works:

A quartz watch is powered, when a battery sends an electrical signal through a piece of crystal quartz

The quartz vibrates at the value of 215  per second, creating a precise frequency.

The vibrations are converted to a single pulse per second, by a circuit.

The consistent movement of the second hand is a result of this pulse, generated every second.

The Mechanical Movement:

Mechanical or manual watches, as the name implies, are driven by a mainspring that must wound, either periodically by hand or with a winding machine.

Instead of being powered by electricity, as seen in the quartz watches, a series of spiraling springs and moving gears power it.

Energy is transferred from the moving gears to power the balance weighted wheel, which oscillates back and forth at a constant rate.

They are not as accurate as quartz watches.

The Automatic Movement:

An automatic movement is a type of mechanical watch, that wounds itself.

It uses the kinetic energy from the motion of the wearer’s wrists.

It is called a self-winding watch.

The significant difference in the build of this automatic watch is the rotor added to the manual parts.

The rotor rotates freely and transfers energy with each movement of the wrist.

The mainsprings automatically wound from this movement.

How Solar Watches Work

A solar watch needs photovoltaic solar cells to work.

These photovoltaic panels, convert sunlight to usable electricity, that powers the watch.

As explained above, it makes sense that solar watches would be built with quartz movement, since a quartz timepiece relies on a battery to power itself and a crystal to control its ticks.

A solar watch is different from other quartz timepieces, because its battery is rechargeable, while other quartz watches are built with disposable batteries.

The Science of Watches:

Watchmakers install a small solar panel behind the dial of the watch.

Photovoltaic cells in the solar panel, have what science calls a photoelectric effect.

The photoelectric effect simply means that these cells can convert photons of light, to electrons.

When light rays hit the face of the watch, the photovoltaic cells in the solar panels, trap the solar energy.

What happens when light rays interact with the photovoltaic cells, you may ask?

Well, electrons begin to move, and these movements create an electric current.

The electron energy is passed through a wire, down to the rechargeable lithium-ion batteries in the watch.

As more electrons jump, more current flows.

So the current depends on the surface area of illumination.

After this energy is stored, it is used to make the watch tick.

The solar cell unit absorbs light rays, that pass through the crystal and converts them to electrical energy.

With the advancement in technology, solar industries have seen considerable improvements in efficiency and functionality.

In the ’90s:

In the 1990s, the solar watches did not store energy up, or have an energy-saving mode for night time, or when the face of the watch was covered from light.

Several years later, Citizen’s Eco-Drive watch series is now able to store up energy, for as long as months/years, without any exposure to light.

The decision to use clean sustainable energy is the best mankind has made, to save the planet.

Creating solar-powered watches is creating one thing with fewer components, that can easily be disposed of, in the environment.

The light rechargeable batteries remove the need to ever replace batteries, thereby reducing the number of toxic materials released into the environment, by disposable batteries.

Such toxic materials are heavy metals; for example mercuric-oxide, zinc oxide, carbon-zinc, lead, or lithium.

The toxic materials are harmful to the environment and humans, if not disposed of properly, for recycling.

How to Recharge a Solar Watch

Just like your laptop sleeps or hibernates to save power, your solar watches can sleep, to save enough energy.

As a human being, you go to bed and sleep. Well, some solar watches hibernate, by stopping the second’s hand from moving, to save enough energy.

So next time you are wearing your watch in the basement or any room without enough light exposure, and notice the second’s hand of your expensive solar watch is not moving, it is no cause for alarm, as it is probably asleep.

Expose it to sunlight, fluorescent, or candescent bulbs, and it will wake up.

For further instructions on how long you can expose your solar watch to direct sunlight, please refer to your owner’s manual or booklet.

To keep solar watches recharged, avoid the following practices:

  • Do not wear underneath a long-sleeve
  • Do not conceal away from any light surface for an extended period, i.e. do not store away in a drawer or bag

Not all solar watches have a power-saving mode.

Verify with your supplier or the company you bought from, the exact details of the solar watch you bought.

Popular Companies that have Superb Solar Watches

Citizen watches:

Citizen Watches started this innovative movement, of Eco-friendly watches.

Eco-drive series were the first solar watches created by Citizen.

Since its launch, solar watches have advanced from just timekeeping pieces to a very expensive, fashionable, and possible lifesaver.

Citizen Watches is competing with other watch brands, such as Casio, and Seiko on solar-powered watch technology.

Though Citizen Watches introduced the idea of solar watches, Seiko came up with other amazing features for solar watches, that made the company grow big enough, to compete with Citizen Watches.

Citizen watches dominated the solar-powered timepiece field for a long time and became a household brand.

Some can arguably say that inventing solar-powered watches was not Citizen’s most innovative creation, but creating an atomic multi-band watch is.

Seiko Company:

Seiko watchmaking company invested more in making elegant and desirable watches.

A Japanese man named Kintarō Hattori, created the watchmaking company, Seiko.

Kintarō Hattori opened a shop selling and repairing watches in Tokyo.

In 1924 he started making watches under the name Seikosha, which got renamed Seiko.

Seiko is a  Japanese word that means “exquisite.”

The two companies make amazing watches ranging from different series and styles.

There is no clear way to discern between them.

Although Citizen and Seiko are competing in the solar-powered watch field, Citizen is leading the way for Seiko.

Seiko makes typically mechanical watches, while Citizen makes quartz watches.

This allows Citizen, to easily place solar panels on any of their watch series or styles.

Seiko is limited because their solar watches can only be for a precise line of watches.

As a shopper, you can go through their range of products and purchase according to your needs.

You can get both brands of solar watches, on Amazon.

The next big competitor is Casio, slightly different from Seiko and Citizen, because of its renowned rugged designs.


Casio is an electronics company located in Tokyo, Japan.

It was created as Kashio Seisakujo, by Tadao Kashio in April 1946.

One of Casio’s superb solar watches is the Master of G Stainless Steel.

This particular watch is no doubt a monster of a watch, as the atomic feature, is just made more impressive, compared to the other solar-powered Casio watches.

The atomic timekeeping feature of quartz watches means there will never be a need, to set or reset the time again.

The only downside to the Casio G-series is the disruptions, wifi, and phone signals cause, alongside the heavyweight.

The Best Solar-Powered Watches

According to watchranker, the list below contains the best watches you can find around;

1. Tissot T-Touch Expert Analog-Digital Display Watch:


This timepiece is a unique piece that shows how the world has progressed, and how time has passed, by displaying time in analog and digital.

It shows multiple time zones and dates.

The numbers and hands are luminescent; you would not have to worry about checking time in the dark.

2. Casio Pathfinder Triple Sensor Sport watch

The battery of the Casio Pathfinder lasts up to 6 months on a full charge.

Unless you get stuck in a dark place without light for six months, this watch will serve you well.

It has a digital compass, a barometer, and it is also water-resistant for 100meters.

3. Citizen Eco-drive Nighthawk dual time watch:

It was built for taking flights.

It has crucial features for pilots. For example, the pilot’s slide rule inner chapter ring operated at the 8 o’clock position.

It is one of the best wristwatches, for pilots.

It is also water-resistant, and the full battery charge can last up to 6 months.

4. Seiko Solar Stainless Steel Chronograph Diver’s watch:

It is excellent for divers.

It has a 200 meters water resistance.

The screw-up and screw-down crown reinforces its water resistance

5. Pro Trek Tough Solar Digital Watch

Features include:

  • Atomic timekeeping
  • Five daily alarms
  • Full auto Electroluminescence backlight with afterglow

We can go on and on about all the best solar watches, but as you can see, Seiko, Citizen, and Casio are pioneering solar-powered timepieces.

Casio is not only known for its rugged looks, but it is also very dependable and reliable.

If you do not mind the heavyweight of Casio G-shock or Pro Trek solar watches, I recommend you get a Casio.

If you are looking for something more sophisticated and elegant by design, a timepiece you can wear with any attire, I recommend you get a Seiko or Citizen solar-powered watch.

Why Get a Solar Watch?

If you are in the military, you must get one solar-powered tactical watch.

The benefits are endless;

  • a tactical watch that is water-resistant and can withstand any change in atmosphere
  • built-in glow
  • reliable quartz movement
  • a compass

Name all the attributes you need in a tactical watch, now imagine that particular watch powered by light.

You never have to worry about changing the battery for at least ten years, the cherry on top of the icing.

If you love hiking, getting a solar watch would is a great idea.

They are very fashionable, practical, and functional.

The endless power supply is a good investment and the rechargeable batteries are Eco-friendly.

There is no need to replace the batteries, for at least ten years, as it is low maintenance.

Cons of Solar Watches:

The major disadvantage of solar watches is its expensive nature.

Not many are willing to part with the huge amount required to purchase one.

However, the price for solar watches is practical, if you consider the science behind them.

So How Do Solar Watches Work?

Solar watches work just like traditional watches, only more functional and efficient.

Solar watches are fast becoming a trend for watch lovers, as these solar watches, are getting better and more reliable, with the advancement in technology.

As shown in this article, the advantages of having a solar watch, surpass the disadvantages.

Solar watches have a never-ending power supply and are environmentally friendly.

There’s little more you can ask for, in one device.

If you have anything you’d like to add to answer the question “how do solar watches work?” feel free to let us know in the comments below.

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