A solar tree is a structure that incorporates solar energy technology into a single pillar, such as a tree trunk. It can be a solar artwork or a functional power generator. Solar trees are aimed at providing visibility to solar technology and enhancing the landscape and architecture they complement, usually in a commercial or public context. One goal of many solar tree installations is to promote knowledge, understanding and adoption of renewable energies. Normally they are not used as primary source of energy for a property; that role is achieved by solar systems on the roof. Solar trees are complementary to rooftop solar systems, or other green building measures, which symbolize these larger investments and their environmental benefit.