Does the solar really work?

The solar functionality for the F6 series isn’t mainly made for charching the battery, it is mainly made for supporting the battery for less battery consumption during activities. So no, you won’t get much battery just putting the watch into sunlight (maybe 2% in 6-8 hrs). 

instinct solar is the only one who can charge and live without cable if in battery save mode. Instinct have much larger solar cells

As said, it won’t charge the watch. I had a 6X pro solar and it was pretty good here in sunny Australia in that day to day use was offset by the solar - eg, I lost zero battery during the day and battery saver during the night limited loss to 1-2%. That’s if I wasn’t doing any activities.

In climates with less Sun, like the UK for example, I could see it as a waste of money. 

The smaller battery size of the 6S means it doesn't get quite the same battery life of it's bigger siblings the 6 and 6X.

But as a first (and free) step, I'd suggest creating a specific power mode on your 6S for your backcountry hiking that reduces battery consumption. An obvious power mode setting would be to turn the phone connection off (you probably don't have much cell signal in the back country anyway). Pulse Ox and backlight should probably be off for hiking too. There is even an option to turn the display off while hiking along (with Gesture reactivation whenever you actually want to look at your watch). And use the Battery Saver power mode overnight. On my F6 Pro, I can use these settings to extend my GPS life from the baseline 36 hours to closer to 50 hours.

Also, continually re-rendering the map screen as you go along is a major processor and power drain. I'd recommend using text data screens as your main screen while hiking, with the map as a secondary screen, and just scroll to the map screen whenever you need to do a navigation check. Using GPS only (and not GLONASS/Gallileo) also gets better battery life.

The next cheapest solution might be to carry a small USB power bank to recharge your 6S during lunch breaks or overnight.

The solar charging is marginal - it needs a lot of direct sunlight, or prolonged exposure over several days to make a meaningful difference. And solar on the 6S is less effective - the smaller face means less solar cells, and the shorter battery life means there is less opportunity to top up the battery. eg. If the solar charging means you can extend the battery by 25%, turning 4 days hiking on the 6 or 6X into 5 days hiking, it would only mean turn 2 days into 2.5 days.

If you are considering upgrading for better battery life, I'd recommend the 6 or 6X over the 6S Solar.

For example:

if I put my 6xPS in bright sunlight without any activity, no sensors etc., I got about 2% charge in 6-8 hrs. If I take my foldable mobile solar panel (20x35 cm/200g, I got about 20%/hr. 

But once again, the solar functionality on the F6 series is working as it is designed for and shall work.

I'm a lady with little wrists, so a regular 6 or 6x wouldn't work for me. This is wonderful advice though. I do think that I might have a defective watch, because I put it in battery saver and in the bright sun (sunny southern USA) for 6 hours, again, and the battery only went down, once again, didn't even maintain. I can't think of any other possible way I could "test" it. I know that when they first brought out solar, Garmin had hardware issues and a lot of the watches had to be fixed. So, perhaps since they just added it to the 6S, maybe there are some kinks to work out and it will get better.

I rarely do much to set up my watch for a hike, just bound out of my car and crash into the forest, and I usually don't look at the map until I am lost (I work at it). So, thanks so much for all those good ideas about extending!

I had the original Fenix and accidently left the gps on during a 3 day hike.  I like it because if I need the watch for a watch and occasional gps tracking, It will be the best Garmin has to offer and add to the value of it.  There is no practical reason for it when you have access to a charger but its nice to have if you don't want to add another pound and you are out in the back country.  I think its a cool feature and to me was worth buying the 6x Pro Solar.

Heck, I'm a guy, and I think the 6 looks kinda chunky on my wrist. I totally get not wanting to feel like you've got a dinner plate strapped to your wrist.

SupaSagi said:

just bound out of my car and crash into the forest,

I like that attitude. 

Seriously though, once you have created an economical power mode, you can set that as the default for hiking, so that you can just press Start for the hiking activity, and hopefully it will just be nibbling at the battery, not chewing through it.

I just wanted to put an update in case there is someone else looking at the 6S Solar. I decided to swap the one I had for the other color and see if there was any difference and there was a big difference. In battery saver mode, at 72%, I left the watch to rise with the sun. Although it had been cloudy, even with only four hours out of eight in gray, the watch had 77% battery! So, definitely saw an effect and I think the first one I had was defective.

I don't expect it to be a power source, but I did expect an effect for the price tag. It's nice to think that if I got badly lost, I could put it in expedition mode and the solar could probably hold it out until I could get out (just so I can justify to myself that there is actually a reason. Lol)