Best solar chronographs

A chronograph, slide rule, dual time, perpetual calendar and radio synchronization across 43 cities, all running on light behind anti-reflective sapphire and rated to 200m.

45mm across and a module rather than a movement. Citizen's five-year warranty is the longest here.

It sets itself by radio, runs on light and is rated to 200m behind sapphire — and it is a module, not a movement. When the module stops being made, the watch is finished, however good the case still is.

The World Chronograph A-T runs Citizen's H800 with atomic timekeeping and radio control in five zones, a 1/20-second chronograph, a perpetual calendar and a power reserve indicator, in a 43mm case behind sapphire rated to 200m.

Five years of warranty. The 23mm lug width is the least common strap size on this site.

Sapphire, 200m, a perpetual calendar and a chronograph that runs on light — and a 23mm lug width, which is the least common strap size on this site. It is a module rather than a movement, so its long-term future depends on Citizen continuing to support the H800.

Seiko's V192 solar chronograph publishes ±15 seconds a month and a six-month run on a full charge, and Seiko publishes $163 for a V-series service — the only solar chronograph here whose running cost you can check.

41.4mm at 45.9mm lug-to-lug is the most wearable size here. 21mm lugs and 100m are the trades.

Seiko lists V-series solar service at $163 — cheaper than a 4R36 overhaul and far cheaper than a mechanical chronograph. The 21mm lug width is the annoyance: standard straps come in 20 and 22.