Economic and legal principles in renewable energy development policy - Solar, Wind and Land: Conflicts in Renewable Energy Development - page 15

property interests in airspace naturally followed. Legal historians
have traced the beginnings of modern airspace law as far back as
the 1300s, when Cino da Pistoia pronounced the maxim: Cujus
est solum, ejus est usque ad coelum , or “[to] whomsoever the soil
belongs, he owns also to the sky.” This doctrine, commonly known
as the “ ad coelum rule,” established simple private property rights
in airspace based upon subadjacent parcel boundaries. The rule was
subsequently cited in Edward Coke's influential commentaries in
the seventeenth century and in William Blackstone's commentaries
in the eighteenth century, cementing it as a fixture in English and
American common law. By the early twentieth century, U.S. courts
were applying the doctrine to find trespass for even minor intru-
sions into the space above privately-owned land. […]
[N]ew airspace uses emerging from the sustainability movement in
recent years have further complicated the task of governing airspace
rights. Difficult new policy questions are arising in part because
… some sustainable land use strategies require the occupation of
additional airspace while other strategies necessitate that more airspace
be kept open.
Growing calls for open airspace
Several types of renewable energy and green development strategies
require open airspace. Unoccupied airspace allows sunlight and wind
to reach plants, buildings, and renewable energy devices without
interruption—a valuable function in our increasingly green economy.
One sustainability-oriented use for open airspace is to prevent the
shading of solar energy devices. The concept of guarding against
solar panel shading is commonly known as “solar access” protection
and has been the subject of numerous statutes, ordinances, and law
review articles over the years. Photovoltaic solar panels and passive
solar energy strategies generate and save significant amounts of power,
thereby reducing an economy's dependence on fossil fuels and other
conventional energy sources. However, these and most other solar
energy devices are far more productive when exposed to direct sunlight.
Shade from trees or other structures in the airspace above nearby land
can thus diminish a solar panel's productivity. The risk that trees or
buildings could ultimately pop up in neighboring airspace and shade
solar energy systems deters some landowners from investing in rooftop
solar installations.
The demand for laws to protect solar access has rapidly grown
over the past few years due to an unprecedented interest in rooftop
solar energy development. Accordingly, government-provided incentive
programs are supporting solar energy more aggressively today than
ever before. As the cost-effectiveness of rooftop solar energy grows,