The best solar watches under $500: seven that never meet a charger, ranked by the dark

Three different things called solar

"Solar" on a watch box can mean three very different ownership experiences, and only two of them belong on this page.

• A solar cell that never meets a charger. Casio Tough Solar, Citizen Eco-Drive, the Epson movement in the Bertucci, the Timex solar movement. Light tops up a rechargeable cell that is a watchmaker-replaceable part. You do nothing, forever.
• A solar lens on a rechargeable GPS watch. Garmin, Suunto. The lens stretches the interval between cable charges from days to weeks. Genuinely useful, not the same thing.
• A token panel and a marketing word. Not on this site.

Everything ranked here is the first kind. The full explanation is in how long solar watches last, and the Garmin version is Garmin solar explained.

The number that matters is the dark figure

Every maker will tell you the watch runs on light. That is not a specification, it is a description. The specification is how long the watch keeps running with no light — a drawer, a winter of long sleeves, a month in a pack. That figure is what tells you how much reserve the cell actually banks, and it is the column this page sorts on.

Every stated figure, side by side

Two things jump out. The PRG-340's 27-month power-save figure is the longest stated number in this whole tier, and it is on the cheapest triple-sensor watch here. And Citizen does not publish a dark-running figure for the BN0151, which is why it sits fourth despite having the longest warranty on the site — we do not fill in a number a maker declines to state.

Why there is no Garmin on this page

Because of the definition above, not because of the price. A solar Instinct 3 sits inside this budget and it is an outstanding watch — it is our pick on half the pages of this site. But its solar lens feeds a rechargeable lithium cell that still ages by charge cycle, and it still ships with a cable. On a page about watches that never meet a charger, that is a different product. The solar-GPS version of this list is best solar GPS watches.

A solar cell still ages

Sensors, sapphire and water

Under $500 you can have sensors or sapphire, not both. The four Casios bring a compass, barometer, altimeter and thermometer behind mineral glass; the Bertucci and the Timex bring sapphire with no sensors at all. The only sapphire Casio we rank is the Mudmaster GWG-2000 and it is well over this budget. On water, the two G-Shocks and the Bertucci are 200 m, the Citizen carries an ISO dive rating, and the Pro Treks are 100 m without mud seals.

The decade pick

How to choose a solar watch

1. Read the dark figure, not the panel. Every maker on this page publishes one except Citizen for this model. It is the only number that tells you what the cell banks.

2. Decide sensors or sapphire. Under $500 that is a genuine either/or. Sensors mean a Casio and mineral glass; sapphire means the Bertucci or the Timex and no sensors.

3. Do you want the watch to set itself? Multi-Band 6 radio time is on the Rangeman, the PRW-61 and the GW-M5610U and not on the PRG-340, the Bertucci or the Timex. It is the difference between adjusting for daylight saving and never touching the watch.

4. Do not store it in a drawer. The one way to kill a solar watch is to leave it in the dark for years at a time. A windowsill is enough. All of these are designed to be worn.