I am not sure, but but I think the solar charging is not charging the battery much on the Fenix series (by design), it is more used for consuming less battery during an activity etc. (on the Instinct solar devices it is more charging the battery/different system). But maybe I am wrong...(?).

This is an interesting POV.

I've checked Fenix Manual and: "

The solar charging capability of the watch allows you to charge your watch while you use it.

Tips for Solar Charging

It's also important to keep the watch and battery at a moderate temperature -- if it's too cold or too hot, it won't charge to prevent damage to the battery. Putting the watch in direct summer sunlight for a couple of hours and expecting it to charge isn't going to work because the battery will be too hot.

Below is an article about Garmin automotive devices, but the information will apply to other devices using Lithium-ion batteries:

Lithium-ion batteries used in Garmin automotive devices are designed to be safely charged between 0°C – 45°C (32°F – 113°F). Charging of the device outside of this temperature range can have detrimental effects on the battery.

support.garmin.com/.../

Thats true. Charging the watch to direct sunlight without do any activity like running or bike can damage the battery (temps can reach over 55°C in direct sunlight)

Can confirm - no charging

It's not exactly like that. The solar charge is not something decorative. In my case it keeps the battery stable at the same rate for many hours even with sensors connected. (enduro 2)

MisterFrag said:

It's also important to keep the watch and battery at a moderate temperature -- if it's too cold or too hot, it won't charge to prevent damage to the battery. Putting the watch in direct summer sunlight for a couple of hours and expecting it to charge isn't going to work because the battery will be too hot.

MikeP said:

Dear MisterFrag,

Thank you for bringing up these technical facts. It's just confirmed that the extra feature that customers have to pay for is not working.

We have a super Fexnix outdoor watch that should not be used outdoors. This is my conclusion.

MikeP said:

I experienced a situation while biking in the south of France I was exposed for a long time to direct sun. As a customer, I expect to take advantage of having this extra "Solar support", but Garmin decided otherwise to cut it off to protect from overheating.

It's now very clear that our Top high-tech watch can be used in the shadows mostly.

I'm sorry for being sarcastic, but the way it's promoted and how it's in the reality it's a huge disappointment.

And suunto is better ? ;)

„CAUTION: 

Do not leave your watch in direct sunlight too long during days with high temperatures as it can damage the watch. „

https://www.suunto.com/en-gb/Support/Product-support/suunto_vertical/suunto_vertical/widgets/solar-charging-only-valid-for-titanium-version/ 

MikeP said:

I'll look for Sunto.

Solar charging is cheating customers. I was a Fenix 6X Pro Solar user. I am a Fenix 7X Sapphire Solar user. I never noticed that the battery was topped up. And I spend a lot of time hiking. Anyway, if there was actually any benefit from solar charging, the sunlight intensity widget would contain information about the amount of energy charged. Requests for such information have been directed to Garmin from the very beginning when solar charging appeared. And it was not realized, because there would be nothing to show there. If it actually worked, the information about the charging status would have been done a long time ago, because every company wants to boast about such information. Here it is simply a scam and tricking the customer with marketing slogans.