Maryland Real Property Section 2-119
(a)   A restrictive covenant regarding land use, which becomes effective after July 1, 1980, may not impose or act to impose unreasonable limitations on the installation of solar collection panels on the roof or exterior walls of improvements.
(b)   This section does not apply to a restrictive covenant on historic property that is listed by:
(1)   The Maryland Inventory of Historic Properties; or
(2)   The Maryland Register of Historic Properties.