555 static solar panel

We have an Anker 555 portable powerhouse which we store in an outhouse. The idea is to mount a static solar panel on the roof to facilitate charging.

The Anker ones are not waterproof or designed for permanent fitting. Also being portable can be subject to being stolen if left unattended.

The manual says “Any 11-28V solar charger with a DC 7909 male connector.” Probably 200w.

I struggling to find a suitable panel.

Has anybody done this successfully?