There are two kinds of solar-heat systems: ""passive""...
There are two kinds of solar-heat systems: ""passive"" systems collect the sunlight that hits your home, and ""active"" systems collect the sunlight that hits your neighbors' homes, too.
There are two kinds of solar-heat systems: ""passive"" systems collect the sunlight that hits your home, and ""active"" systems collect the sunlight that hits your neighbors' homes, too.