Light for Cacti and Succulents

Succulents (Including Cacti) should be kept in a light, airy position all the year round. A south-facing window is ideal for most types, although some "other succulents" e.g. Aloe, Gasteria, Haworthia will be quite happy in more shaded situations.
In general, to keep looking healthy, a succulent plant should have sunlight falling on it for at least part of the day. Many would be quite happy with either morning or afternoon sun in an East or West window.
If all you have is a north-facing window, which never gets any sun, try installing a plant light, or put your plants outdoors for the summer. A North-facing window would be suitable only for some Epiphytic cacti such as Christmas & Easter Cacti and Rhipsalis, and a limited selection of other succulents such as Aloe, Gasteria, Haworthia & Sansevieria. Even these plants would flower better under these conditions if they could have even a brief "holiday" in the garden.