Solar Watch Technology - A Brief History
During the late 1950s, the watch industry was at the precipice of a technical revolution that would nearly take down the entire Swiss mechanical watch industry while simultaneously ushering in the dawn of mass-produced electronic watches. This era was eventually known as the Quartz Crisis, and early on several technological approaches to producing electronic watches were entering the market and competing for market share. Ultimately, the Quartz movement as we know it today won out and by the 1970s had become the dominant electronic watch movement type in the industry. However, during the late 1960s, the development of the first solar-powered movement took place by American engineer Roger Riehl. This technology was introduced to the market in 1972 with the first prototype called the “Synchronar”. The first production piece was released later that year with the Synchronar 2100.
While the quartz technology was becoming cheaper and more accessible, the Synchronar 2100 was still seen as a luxury and struggled to catch on with its high price point of nearly $500, which would be roughly $3200 in today’s money. Nevertheless, the Synchronar 2100 set the stage for brands such as Citizen to utilize solar technology by the mid-1990s when the technological costs decreased and production capacity increased. Today, Citizen’s Eco-Drive technology has gone on to dominate the solar-powered watch market and is perhaps the company’s most endearing contribution to the industry. Citizen isn’t the only company utilizing solar technology today either, nor is the technology limited to mass consumer products. Brands such as Tissot, Seiko, Casio, and Cartier, among others, are all now harnessing solar technologies within their product line.
How Solar Watches Work
As the name suggests, solar watches capture, store, and convert light energy into electrical energy. Early solar-powered models had fully exposed solar cells that faced the sun, either on the dial or on top of the case. The Synchronar 2100 went with the latter option and placed the solar cells on top of the case, giving the watch a futuristic look. Today, a solar cell is placed just under the dial to achieve the same results. As light is captured by the solar cell and converted into electrical energy, it’s then relayed to a rechargeable battery where it's stored. Solar cells not only collect light from the sun, but they also collect artificial light, albeit at a slower rate.
Advantages of Solar Power
Solar power offers several technical advantages over both traditional mechanical movements and modern quartz technologies, making it an appealing option in the market. First and foremost, it harnesses energy from the ultimate energy source - the sun. Fortunately, we aren’t going to run out of sunlight for at least another billion years, so there’s plenty of light energy to capture and convert. Two, the storage of energy in solar watches, in the context of power reserve, far exceeds anything any mechanical watch can achieve. It's also a feature that's completely absent in traditional battery-operated timekeepers. Three, regular maintenance intervals for solar watches are few and far between. Since these movements don’t require any lubrication nor a standard battery, regular servicing intervals can be a decade or longer. Finally, solar power movements are as accurate as their battery-operated counterparts, utilizing a quartz crystal to power the gear train at extremely high frequencies making these watches accurate within just seconds per month. The low cost of ownership, relatively inexpensive price point, and high level of accuracy make solar technology a legitimate third option among the mechanical and battery-powered timepieces.
Solar Powered Options
Below is a curated list of some solar-powered options across different price points from the iconic Casio G-Shock Full Metal 5000 to the new luxurious Cartier Tank Must SolarBeat.
Tissot T-Touch Connect Solar
Tissot brings together both solar and smartwatch technologies with the T-Touch Connect Solar. It’s an impressive piece with equally impressive size, coming in at 47mm in a hypoallergenic titanium case. It connects to your mobile device with Tissot’s proprietary app, syncing messages, calls, and alerts while also providing health monitoring functions. True to its name, the T-Touch has a tactile crystal that allows the wearer to select functions by touching the large, interactive screen. Yes, the size might be limited to some larger wrist sizes, but the added smartwatch functionality markets itself to individuals outside of the watch enthusiast segment of buyers out there where case size is secondary to the tech.
Case: 47.5mm, Thickness 15.3mm, Lug-to-Lug: 60mm, Crystal: Tactile Sapphire, Movement: Solar Quartz E32.001, Water-Resistance: 100m, Price: Starting at $1050 on the rubber strap
Seiko Prospex SNE435
One benefit to a solar-powered movement that tends to get overshadowed by the technology itself is its thinness, which in turn allows for a thinner case. In the dive watch category where thickness can be prohibitive for some, the SNE435 maintains a thinner profile than many other options in this category. While it’s not small at 43.5mm, its sub 12mm thickness is a welcome byproduct of the thinner solar movement inside. In classic Seiko form, the SNE435 has high levels of finishing throughout the case and bracelet and sports some of the best lume in the industry.
Case: 43.5mm, Thickness 11.6mm, Lug-to-Lug: 50mm, Lug Width: 20mm, Crystal: Hardlex, Movement: Solar Quartz V157, Water-Resistance: 200m, Price: $395
Casio G Shock Full Metal 5000
A favorite among military service personnel, firefighters, and police, the G-Shock embodies extreme durability and reliability with its iconic design. With models starting under $100, it’s no wonder they are so popular and if you’re willing to spend around $500, you can get into the solar-powered G-Shock Full Metal 5000. Like the Tissot T-Touch, the Full Metal 5000 combines solar power with smartwatch technology, syncing the time with your cellular device and keeping dead-on accuracy. Pairing all this technology with one of the toughest case designs in the world and you have a timepiece that sets the standard for an everyday wearer.
Case: 49.3mm x 43.2mm, Thickness 13mm, Crystal: Hardlex, Movement: Solar Quartz Module 3459, Water-Resistance: 200m, Price: $550 on the bracelet
Seiko "Arnie" SNJ025
Based on the Seiko reference H558-5000, a watch which made its way onto the wrist of Arnold Schwarzenegger in 80's action blockbusters Commando and Predator, the SNJ025 was launched in 2019, retaining the tuna-style case concept and ana-digi display while also upgrading the watch with a modern solar quartz caliber that addressed the at times poor battery life associated with the original watch. The SNJ025 is a watch made for a Mr Olympia, being even larger than the original watch that measured just under 46mm. Along with this size, you get a true ISO certified dive watch with 200m of water resistance with impressive lume, as one would expect from Seiko.
Case Size: 47.8mm; Thickness: 13.8mm; Lug-to-Lug: 50.5mm; Lug Width: 22mm; Water Resistance: 200m; Movement: Seiko Quartz H851; Crystal: Hardlex; Price: $525
Citizen Eco-Drive Promaster Nighthawk
The current generation Citizen Promaster Nighthawk is a refreshed military-inspired aviator that goes big on the functionality and bold on the design. The sporty 42mm case features a slide rule bezel to go along with the dual time zone, chronograph, and date. More than just for fun in the sky, 200m of water resistance means it has some underwater abilities, too. Powered by Eco-drive, the Nighthawk will be ready when you are, whether it's your daily wearer, your weekend go-to, or something you throw on just once in a while. Two color options are available, one in steel with a sunburst charcoal dial on the olive drab strap and an all-black version as well.
Case Size: 42 mm, Thickness: 12.5 mm, Lug-to-Lug: 46.5 mm, Water Resistance: 200 m, Movement: Eco-Drive, Crystal: Sapphire, Price: $495
Citizen Eco-Drive Garrison
Solar technology isn’t limited to any particular style of watch, although it’s most closely associated with sportier timepieces. However, with the Citizen Eco-Drive Garrison, you get the benefits of the quartz accuracy, the six-month power reserve, and low-cost technology packaged in a casual, military-inspired field watch with really good everyday versatility. The Garrison is a no-nonsense approach to displaying time with large bold Arabic numerals loaded with lume and hands that complement the dial design well. At 42mm it’s a bit larger than some popular mechanical field watches from Hamilton and Bulova, but the Garrison comes in at less than half of the price as these other options.
Case Size: 42 mm, Water Resistance: 100 m, Movement: Eco-Drive E111, Crystal: Mineral, Price: $200
Citizen Promaster Diver Eco-Drive
Perhaps the most important technological advantage of solar-powered watches is their ability to perform when called upon. This is why the Citizen Promaster Diver is a widely regarded choice among professional divers who don’t necessarily see themselves as “watch people”, but instead rely on high-performance equipment to keep them safe. The Eco-Drive version of the Promaster Diver is one of those tool watches that makes good sense, with its six-month power reserve and decade-long service intervals. It can be trusted to perform at a high level inside, while the external features include bold and easily legible hands and markers along with rock-solid bezel action.
Case Size: 44mm, Thickness: 12mm, Lug-to-Lug: 49 mm, Lug Width: 20mm, Water Resistance: 200 m, Movement: Eco-Drive E168, Crystal: Sapphire, Price: $221.50
Cartier Tank Must SolarBeat
Cartier's introduction of the Tank Must SolarBeat in 2021 is an interesting move by one of the world’s most important luxury brands. Not only is Cartier embracing solar technology but they’ve decided to utilize it in their most iconic collection, the Tank. In many ways, this move into solar and away from traditional battery-powered movements, makes a lot of sense, particularly in a women’s model. Solar has proven itself to be one of the best set-it-and-forget-it options available. Of course, this is a step up in price relative to the other options on this list, but within the luxury market, the $2600 price point fits well within the Cartier catalog of quartz Tanks models.
Case Size: 33mm x 25.5mm and 29.5mm x 22mm, Thickness: 6.6mm, Water Resistance: 30 m, Movement: SolarBeat, Crystal: Sapphire, Price: $2610