I am interested in this conversation too, since I'm also new to the forum and grow my orchids on a widowsill. In the spring/summer months, I think my plants get around 4 hours of direct sun in the morning until around 11:30am; after that its just very bright indirect light. With my poor fiance not being too into orchids, there is NO way I could get supplemental lighting either...I'm just grateful that my window doesn't face north! haha