Abstract: Solar building construction utilizing a rectangular shaped module, typically square, from which a corner has been cut-off or removed. The opening left in the module by the cut-off corner is panelled and closed in with glass. The module is oriented so that the glass panel, which may include sliding or hinged glass doors, faces in a direction that is exposed to the sun for a maximum number of hours during the colder winter months when the sun is relatively low in the sky. The sun's rays are allowed to deeply penetrate into the interior of the module through the use of open space and carefully positioned interior walls. At least some of these walls are typically perpendicular to the plane created by the glass panel. Both interior and exterior walls, and other fixtures within the modules, are realized using items having a favorable thermal mass.