WATCH RITUAL
Guides / Movements
Movements · 2 min read

Eco-Drive vs Seiko Solar: how light-powered watches work.

Eco-Drive and Seiko Solar watches use a light-sensitive cell under the dial to charge a rechargeable power cell, so you do not change a battery in the usual way. The idea is the same for both: wear the watch in daylight or leave it by a window, and it keeps running. The differences come down to specific models, features and servicing.

By Sebastian Bassolino, Editor · Updated October 17, 2026

How a solar watch works.

A solar cell sits under a translucent dial and converts light into electricity. That energy is stored in a rechargeable cell and used to drive a quartz movement. Citizen calls its version Eco-Drive and lists its watches as powered by any light source; Seiko’s equivalent is Solar. Neither needs a regular battery change in the usual sense, although the rechargeable cell can eventually wear out.

Keeping one charged.

  • Wear it uncovered by a cuff for part of the day, or leave it in a bright spot overnight.
  • Do not store it in a drawer for months; a deeply discharged cell can be slow to recover.
  • Follow the maker’s manual for charging guidance and for the model’s power-saving behaviour.

Features you can add.

Light power also runs more advanced functions. Some Citizen models add atomic time synchronization, a perpetual calendar and a power reserve indicator; the Citizen PCAT and the Skyhawk A-T are examples. Simpler models, such as the Peyten, offer a plain three-hand display.

Solar vs battery quartz vs automatic.

TypePowerMaintenanceBest for
Solar quartzLight-charged cellLow; no regular battery changesAccurate, grab-and-go use
Battery quartzReplaceable batteryA battery change every few yearsSlim, simple watches
AutomaticWrist motion and mainspringPeriodic servicingMechanical movement fans

Which should you choose?

If you want the lowest-maintenance watch with no winding, a solar watch is the best choice. If the mechanical movement is the appeal, an automatic suits you better. Watch movement types explained.

Solar watches we recommend.

A few good questions.

How does an Eco-Drive watch work?

A solar cell under the dial charges a rechargeable power cell from any light, and that cell runs a quartz movement.

Does an Eco-Drive watch need a battery?

It does not need regular battery changes. The rechargeable cell can eventually need replacing, so check Citizen’s manual and service advice.

Can I leave a solar watch in a drawer?

It is better not to. Leave it in light regularly so the cell stays charged.

Is Seiko Solar the same as Eco-Drive?

They work on the same principle, light charging a rechargeable cell. The models, features and servicing differ, so check the maker’s information for the exact watch.

How we write guides: we explain watchmaking from manufacturer documentation and published standards, and say plainly where numbers vary by brand or movement. Our approach.