bifacial

Bifacial is an adjective meaning having two faces or two sides. The word comes from the Latin bi- meaning two and facies meaning face. It is used across different fields to describe objects or features that present surfaces on both sides.

In archaeology and anthropology, bifacial tools are stone implements shaped by flaking on both faces to create a symmetrical form. Common examples include handaxes, cleavers, and certain points sculpted from both sides rather than along a single surface. Bifacial technology is associated with various prehistoric industries and years, with the degree of refinement and the types of tools varying by region and era. The term distinguishes these tools from unifacial tools, which are worked on only one face.

In modern technology, bifacial describes photovoltaic devices that generate electricity from light hitting both the front and rear sides of the panel. Bifacial solar modules can increase energy yield under appropriate conditions, particularly where there is reflective ground cover or elevated mounting that allows rear-side illumination. Design considerations include the albedo of the surface beneath the panels, mounting height, and potential shading, all of which influence the practical gains of using bifacial panels compared with traditional single-face modules.

Other uses of the term may describe two-faced design or two-sided features in crafting, manufacturing, or architecture, always emphasizing the presence of two functional surfaces.