You don't need a solar watch
You may think you need a solar battery powered watch. You don't.
Years ago, it used to be used that finding a wristwatch powered by a solar battery was really easy. Is it still easy today? Yes, but you don't really need it.
Before getting into why you don't need a solar watch, the main reason why anybody buys one in the first place is for the possibility of getting 20 years out of the original battery.
Does this actually happen? Yes, but only under very specific conditions for digital LCD watches.
Condition 1: The watch is exposed to bright sunlight every single day.
Condition 2: The night light, alarm and hourly beep, if the watch has these features, are never used.
Condition 3: The watch has the capability to go into a power-saving mode.
Condition 4: At night, the watch goes into its "highest level" of power saving where the display turns off until you press a button to turn it back on to read the time.
In other words, if the wearer gets outside a lot, has the power saving mode set so it uses as little power as possible, and only uses the watch to read the time and absolutely nothing else, yes it is possible to get 20 years out of the original battery.
Realistically speaking, the best you can hope for is 10 years or maybe slightly longer if you're lucky...
...and that brings me to why it's not even worth it to buy a solar powered watch.
All three have a "10 year battery" in them, and none are solar powered.
Can these watches run on the original battery for 10 years? Absolutely. If the night light is only used sparingly and the alarm and hourly signal aren't used, yes, you can get 10 years of use on the original battery or close to it.
Heck, even the extremely common F-91W will usually get 5 to 7 years on its original battery, and that's not even a "10 year battery" model.
Ultimately, a solar model and a "10 year battery" model have about the same battery longevity. The only difference is that the non-solar models are easier to own. Why? Because you don't have to worry about exposing it to sunlight (or just really bright light) to keep up its charge.
What about Citizen Eco-Drive?
How long does an Eco-Drive last? Citizen claims it's forever. Specifically, this:
Under normal conditions in door and outdoor, there is ample exposure to light to keep the watch running - forever.
Citizen said that, not I.
Is that true? I don't know. Forever is a long time.