Instinct solar

Can you tell me please where Garmin states in the manual that it does not recommend screen protectors? I have used the search function, but didn't find anything about screen protectors there. 

It will probably waste some fraction of the solar intensity but not a big deal. So yes any old instinct's protector would do I suppose

I've not noticed any issue with the screen protector and I live in rain drenched England. I'm using the CAVN Ultra Protection. Very easy to fit and can't tell its there.

Ive also used a screen protector on my solar, i did some test before and after with a constant lightsource and the sun, and i could not see any difference in solar intensity or charging. 

Maybe it will affect like a few %, or maybe not at all, i think its just for legal claims they write it.

Anyway, i'd rather have a few % slower charing with solar than a scratchy/broken screen that wont charge at all 

Totally agree. I had to replace my first 520 because i failed to put a screen protector on it. It was a costly mistake.

I have glass protection, I don't see the difference, I did the measurements. Satisfaction with protection comes first.

I put a screen protector on my Instinct Solar and the solar charging works just fine. I tested it out for 6 hours on a sunny day and I checked the widget. Full power and I gained “days” in reserve. 

I can’t attest to all but this is what I’ve used on my regular Instinct and Solar version, again with no issue:

Asked Garmin the question via messenger and they pointed me to faq where they don't recommend a screen protector. From my tests my tampered glass (not flexible plastic) protector didn't affect solar charging. When left in direct sun with and without the protector it was charging on average 1.5% per hour (sunny day in UK).