In 1860, Auguste Mouchout patented the first engine powered by solar energy. In 1958, Vanguard I became the first satellite to use the Sun’s rays to generate its own electricity. In 2010, Sol Invictus, by Cabestan & Marc Alfieri, is the first mechanical watch in the world to integrate a perpetual winding system powered by solar energy.

Sol Invictus incarnates the new generation of exclusive watchmaking : three of the leading names in the industry, Marc Alfieri, Jean-François Ruchonnet and Eric Coudray, worked together to create the unimaginable. Sol Invictus, Invincible Sun, god revered by the Roman Emperor Aurelian, is today the name of this extra ordinary creation.


Marc Alfieri, an avant garde watchmaker, is also a major actor in the large scale deployment of solar panels in France. During a meeting with Jean-François Ruchonnet, this experience led him to the idea of combining the astonishing movement of the Cabestan Winch Tourbillon Vertical, with its chain and fusée, drums and vertical tourbillon, and a rewinding system powered by solar energy at a scale never seen before.

The vision was to link the Cabestan’s micromechanics to miniature photovoltaic cells, store energy and then draw upon it as needed, to electromechanically set the time and perpetually rewind the movement.


Marc Alfieri, who installs vast surfaces of solar panels capable of generating 100 megawatts of electricity, adapted this technology to Sol Invictus to produce only 100 milliwatts, or one billion times less power. To achieve this, he worked with l’INES (l’Institut National de l’Energie Solaire) who recently developed a revolutionary new technique for producting and treating silicium crystals that can be used to produce highly efficient solar cells that are especially suitable for small surfaces and low luminosity. Sol Invictus will have the honour of being the world’s first commercial utilisation of this groundbreaking technology.

Two brushless micromotors are employed, one for rewinding the movement and the other for setting the time. Typically used in the medical industry, they have a diameter of only 1.9 mm and a length of 5.5 mm. A miniature controller regulates and amplifies the electrical charge, manages the two micromotors via a programmable oscillator and assures the direction and the speed of the motors. To activate and deactivate the motors, a twin-blade electromechanical contact is used to open and close the electrical circuit. The result is an amazing system for powering the movement, based on an exciting combination of the latest in solar technology and century old electromechanical know-how.


Jean-François Ruchonnet, working with Marc Alfieri, placed his spectacular vertical Cabestan movement in the center of the timepiece. Perfectly balanced at 12 o’clock and 6 o’clock, he added two solar panels mounted in metal frames held in place by cleverly designed pivots. The micromotors and rechargeable lithium-ion batteries are positionned to be discretely visible underneath the solar cells. In the middle of the movement, the twin-blade contact and its glass casing, based on the designs of 19^th century scientist Léon Foucault, is eminently visible. The complex mechanism that links the crown to the movement also includes a striking 30 mm long axle that traverses the movement in its width. Finally, the watchcase is inspired by Marc Alfieri’s designs, but Jean-François Ruchonnet restyled it, giving it an elegantly curved shape, a single curved crystal, a lateral window at 9 o’clock and a sapphire case back all designed to increase the visability of the incredible mechanism inside.


Eric Coudray had the task of working with Jean-François Ruchonnet’s design and Marc Alfieri’s solar energy system, to integrate the technologies used and make sure that Sol Invictus works perfectly. He started by creating an elaborate system that automatically detects when the barillet needs to be rewound. At the end of its power reserve, a magnet automaticallly moves next to the glass tube containing the twin-blade contacts. The magnetic attraction closes the electrical circuit and starts the rewinding sequence. The energy delivered by the motor passes through a set of differential gears before rewinding the movement by acting upon the chain and fusée. Once finished, the magnet is moved away and the contact opens to stop the motor. A separate motor is used to set the time electro-mechanically. The multifunction crown is equipped with a releaseable mechanism that enables the owner to rewind the watch both electromechanically and manually, and to set time electromechanically.


For 7000 years, the Sun has been at the center of telling time, but it has never before been harnassed to assure the perpetual functionning of a mechanical timepiece. Sol Invictus breaks with the norms of traditional watchmaking and pushes back the limits of the imagination: the combination of an ingenious idea and a spectacular movement that becomes reality. A work of mechanical art destined for the world’s most demanding collectors. The art of watchmaking pushed to the extreme. And a highly successful collaborative effort that is emblematic of the new generation of watchmakers.

Base price in titanium : CHF 595,000

Each timepiece will be produced on demand using the materials and configuration desired by its future owner, making each piece unique.

Cabestan Winch Tourbillon Vertical, since its creation, has been heralded as an icon of ingenuity, combining elegance, innovation and a decidedly strong character. Its creator, Jean-François Ruchonnet, was quickly joined by Eric Coudray, a master watchmaker known by collectors around the world. Together, they completed the intricate development of this groundbreaking movement.

Cabestan has its own manufacture situated in the Vallée de Joux. With a team of six highly qualified watchmakers, it is one of the rare independent watchmakers of its size to have its own truly complete production facility.

Cabestan Winch Tourbillon Vertical has been a sensation in terms of design and technical ingenuity. With its chain and fusée, a tourbillon placed vertically, drums for reading the time and a miniature winch to rewind the movement and set the time, it breaks with the design constraints of traditional watchmaking. Cabestan has just proudly delivered its 30^th timepiece, each one being regulated with incredible precision: ±1 second per day.

In 2010, the manufacture developed the Cabestan Nostromo, the second interpretation of the spectacular Cabestan movement. Sporty and masculine, with ingenious drums and bridges, and a never before seen nocturnal life, Cabestan Nostromo is amazing.

Cabestan is proud to seduce and to inspire watch collectors around the world. Totally authentic, Cabestan watches are works of mechanical art, entirely made by hand, corresponding to the very special demands of aesthetes and collectors of exceptional timepieces seeking exclusivity and the utmost in quality, performance and design.