The solar cell only extends the battery life, you still need to charge it (about once a month). There are several other Fenix 6 models too.
Garmin fenix® 6X - Pro Solar Edition
Garmin Launches Solar Smartwatches
Garmin fenix® 6X - Pro Solar Edition
Garmin Fenix 6 Pro Solar review: the solar-powered super watch, Smartwatches
Garmin fenix 6X Pro Solar, Premium Multisport GPS Watch with Solar Charging Capabilities, Features Mapping, Music, Grade-Adjusted Pace Guidance and Pulse Ox Sensors, Dark Gray with Black Band : Electronics
Review: Garmin Fenix 6 Pro Solar
Garmin Fenix 6X Pro Solar Smartwatch Review – sport watch and offline satnav in one - Reviews
Garmin fenix® 6X - Pro Solar Edition
Garmin Fenix 6X Pro Solar Smartwatch Review – sport watch and offline satnav in one - Reviews
Garmin fenix 6X Pro Solar Multisport GPS Watch
Garmin unveils Fenix 6X Pro Solar, its first (partially) solar-powered smartwatch - news
Do what you love longer with Garmin's all new solar-powered smartwatches
Fenix 7- this is the end - Fenix is dead, long live Epix