Indoor sun is not direct because regular window glass filters out most of the UV and maybe 10-15% of the visible light.
You cannot give your Pleiospilos too much sun indoors (given good ventilation and moderate temperatures). I have one growing by a SW-facing window that gets hours of daily sun year-round and it flowers every year. Awesome smell on the flowers, sometimes more intense than others, like piña colada. Mmmmm. It has opened every afternoon for the past week.
