I think it's too dark even for phals. The key word is "acclimatise", meaning you can train your orchids into your local conditions, as long as they don't sit in the sun all day long! My guess is that window sill looks like a hot seat, and given the fact that you keep them in s/h, the water will become hot during the day and phal roots don't like that.
I think that a small plant stand close to the same window will be perfect, as long as you keep the pots in cache pots so the water doesn't boil :P