Placement and dimension are two critical considerations. Skylights should be situated so that they bring light (and ventilation) into areas that can use them. This sounds too simple, but we often see skylights directly over a dining room table or where the skylight makes the television hard to view. Kitchens and bathrooms need venting units if possible. Also, a prominent location inside the house may present a different set of issues from the roof: ridges, valleys, and all sorts of obstacles in the attic. The dimension or size of a skylight is also an issue. What seems large right in front of you is often too small, 12 feet overhead. Be careful not to undersize the skylight. Placing several units next to each other becomes very dramatic. Including the option to vent your new skylights is always something to consider, especially with the solar tax credit.