Harnessing the Sun: Five Extraordinary Solar-Inspired Timepieces

Watches that harness solar power allow for a fascinating intersection of ancient timekeeping and modern innovation. These timepieces not only run on solar energy, eliminating the need for battery replacements, but some of them also feature the ability to display solar time, aligning more closely with Earth's natural rhythm. The concept is, of course, not entirely new; in ancient times, sundials and celestial navigation displayed remarkable precision. 

Indeed, solar time functions reflect a growing appreciation for natural timekeeping, often used in high-end or specialized watches to appeal to enthusiasts who love astronomy or traditional timekeeping. In such watches, solar-powered movements convert light, whether from the sun or artificial sources, into energy stored in rechargeable cells, offering incredible convenience and environmental benefits. Together, these features make solar watches not just eco-friendly or technologically impressive; they also tap into humanity's timeless connection to the cosmos. 

GMT India, therefore, looks at five of the most compelling watches that harness solar technology, whether through solar-powered movements or by tracking solar time with innovative displays.

Tissot PRC 100 Solar

Each of the two models, Ref. T151.422.11.031.00 and Ref. T151.422.11.041.00, in this category gets a stainless steel case, a crown at 3 o’clock, and a dodecagonal bezel. The third one (Ref. T151.422.33.051.00) has a stainless steel with black PVD coating case, a bezel, and a crown. Common to all models, housed in 39 mm cases, is a white minute track on the outer periphery of the dial; Super-LumiNova coating can be spotted on the hour markers, and hour, minute, and second hands. 

Additionally, all models have a date window at 3 o’clock. Powering the models is a quartz solar movement with an Accumulator-type Panasonic CTL920F battery, showcasing an advanced Lightmaster technology. The closed caseback of each watch is crafted either in stainless steel or in stainless steel with black PVD coating.

TAG Heuer Formula 1 Solargraph

At the recently concluded Watches and Wonders, TAG Heuer, the official timekeeper for Formula 1, released the new TAG Heuer Formula 1 references. These releases celebrate an icon of the 1980s and add one more anchor to racing-inspired watchmaking. With a refined 38 mm case size, an upgraded finishing including sandblasted steel and DLC treatment, an enhanced ergonomic design, a cutting-edge Solargraph movement, and an eye-catching range of colourways, the Formula 1 variants put TAG Heuer in the fast lane yet again.

And as the official timekeeper of Formula 1, there has never been a more fitting moment to reignite the energy of this legendary collection. With the Solargraph movement, the watch’s battery is recharged by the sun or artificial light. A two-minute exposure to direct sunlight is enough to power each watch for an entire day. Once fully charged, after less than 40 hours in the sun, each watch can run for up to 10 months with no light exposure.

Seiko GPS Solar Dual-Time Chronograph

As part of Seiko’s Astron series, the GPS Solar Dual-Time Chronograph models showcase the watchmaker’s stupendous progress in harnessing solar power for timepieces. Featuring GPS-controlled time synchronisation and solar-powered efficiency, the collection has a GMT function watch as well as a dual-time watch showing two time zones, but they work differently.

Each of the new Seiko chronographs comes in a 44 mm titanium angular shaped case; it has a 60-minute bezel and a fluted crown positioned at 3 o’clock, flanked by two robust block-shaped pushers at 2 o’clock and 4 o’clock. The limited-edition model gets a faceted dodecagonal rose gold-coloured titanium bezel and rose gold-coloured accents on the hour markers. The dial layout remains true to the Astron’s signature style, packed with functional elements. Running the watches is GPS Solar OCalibre 5X83 with a power reserve of six months (when fully charged); each watch can save power for two years.

Breguet Marine Tourbillon Equation Marchante 5887

The Tourbillon Equation Marchante is housed in a 43.9 mm platinum case with a thickness of 11.9 mm. The lugs are integrated within the case; the watch gets a crown at 3 o’clock with wave-shaped crown guards and a polished bezel. Crafted from white gold, the dial has black finishing, hand-guilloché "wave" motifs. The 18 ct gold appliqué black Roman hour markers are placed below a brushed silvered circle. On top of each hour marker is a pyramid in 18 ct gold and luminescent material. This watch simultaneously displays the difference between mean solar time (calendar hours and minutes) with blue emissions and true solar time with baton, gold-plated rings (used since ancient times).

Enhancing the overall look are a retrograde hand from 9 to 3 o'clock, graduated from 1 to 31, and applied 18 ct rhodium-plated gold windows for the day at 10:30, and for month and leap year at 1:30. The rhodium-plated hour, minute hands have Breguet tips in 18 ct gold, faceted with Super-LumiNova®. The tourbillon opens at 5 o'clock. Powering the watch is Calibre 581DPE, numbered and signed Breguet. This self-winding movement has a flat silicon spiral, a silicon escapement wheel, an inverted rib anchor, and silicon horns with a single barrel offering an 80-hour power reserve. Turning the watch over showcases the sapphire crystal caseback with an engraved platinum peripheral oscillating weight decorated with a "wave" motif wrapped around the hand-chiselled back of the calibre 581DPE depicting the silhouette of the Royal Louis, a Royal Navy warship commissioned in 1752. The barrel is decorated with a hand-engraved compass rose.

Jaeger-LeCoultre Master Grande Tradition Calibre 948

This timepiece stands out for its one-of-a-kind worldtimer tourbillon movement. The calibre 948 now has minor variations, such as a new balance wheel, referred to as a Universal Tourbillon by the Grande Maison. It combines the tourbillon's regulator minute-by-minute spin with an orbital rotation around the dial every day. As a result, the flying tourbillon spins around the watch once every day, tracing the 24 hours and recreating Earth's rotation on its own axis.

This daily revolution of the tourbillon (together with the central map and city ring) enables the watch to display time in all 24 time zones. This domed map is mounted on a base plate depicting the oceans in blue-green translucent lacquer with a wavy guilloche pattern. Each dial takes 70 hours of effort. The Jaeger-LeCoultre Master Grande Tradition Calibre 948 has a 43 mm 18 ct pink gold Master Grande Tradition casing with a 48-hour power reserve.