Indiana state law includes both covenant restrictions and solar easement provisions. The state's covenant restrictions prevent planning and zoning authorities from prohibiting or unreasonably restricting the use of solar energy. Indiana's solar easement provisions are similar to those in many other states. Although they do not create an automatic right to sunlight they allow parties to voluntarily enter into solar easement contracts which are enforceable by law. Passive solar structures are explicitly included in the type of solar-collection equipment that may be protected by solar easements.