I saw this photo on a Hungarian site.
Do you know its cultivar name?
Here is a link that might be useful:
Could be Hibiscus rosa-sinensis 'Yellow Star'
I can not find a picture of the Yellow star in Google.
Do you have a picture of it?
No, I can't even find the link to the picture I saw yesterday but after looking at your picture more closely, I doubt it's the Yellow Star. The picture I saw was a true yellow while your's is more peach\gold. The distinctive star in the throat should help you pin it down.
My suggestion is to keep searching Google, using different descriptions. Maybe try "Gold Tropical Hibiscus with red star throat" or something similar.
Additional info: the plant is 20 years old and very slow growing.