Opponents likewise contend that publicly visible solar panels atop multiple houses on a street in a historic neighborhood — such as Capitol Hill, Georgetown and Old Town Alexandria — will adversely alter the visual, historic character of both the street and the neighborhood.
Rooftop solar panels on homes in historic D.C. neighborhoods, as in other cities, provoke controversy about the pros and cons of preservation policy and regulation. Solar panels are yet another appearance-changing item added to a growing list of concerns since preservation became part of America’s cultural, political and regulatory agenda after World War II.
Physical, property-specific challenges greatly complicate historic preservation judgments. Because many variables exist, no one-size-fits-all policy and set of regulations can fairly govern rooftop solar panel installation on individual houses or in residential neighborhoods.
Variables include house height and street setback; street width; street and house orientation relative to seasonal movement of the sun; height and density of tree canopies lining a street and in front yards; house facade composition; and roof type and geometry.
For example, along narrow residential streets lined by two- or three-story homes on deep lots with shallow front yards, solar panels can be unseen. On both sides of such streets, south-facing panel arrays can be placed at the rear of the house rooftop, well set back from the front facade. But on wide streets with deeper front yards, solar collectors on two-story houses will be more easily noticed, especially from across the street.
Flat-roofed, multistory homes offer the most flexibility for positioning solar panels to be visually unobtrusive. More difficult are pitched-roof homes with a south-facing roof plane sloping up from the front facade eave to the roof ridge parallel to the street. This common roof geometry is typical of many rowhouses, especially in historically designated neighborhoods. Solar panels on such houses will be visible.
Complicating site attributes and roof geometry considerations is the question of whether a house and its constituent elements are sufficiently “historic” to merit preservation. When, if ever, should a house be judged off-limits for rooftop solar panel installation?
Preservation worthiness is a matter of value judgment, transcending analysis of history. Many vintage buildings have been substantially modified over time, with elements of diverse historic quality and character added, removed or changed. Many other houses were never exemplars of quality design even when first built.
What you believe to be certifiably historic can be different from what your neighbor believes, even when facts are not in dispute. Preservation experts likewise differ, intensifying debate about solar panel installation.
Beyond these considerations are property rights issues.
Many homeowners think they should be free to use legal, safe, state-of-the-art technology, both to save money and to reduce carbon emissions. By installing solar energy collectors, they see themselves as public-spirited citizens for whom technological progress is of higher priority than aesthetic, cultural considerations tied to the past and merely a matter of taste.
In their view, solar panels are destined to become an accepted part of future residential architecture. They expect architects to design houses with attractively integrated solar energy collectors no longer considered eyesores.
Or perhaps they anticipate a future when renewable energy technologies will lead to centralized generation and distribution of electrical power at a cost low enough to make rooftop solar collectors economically impractical and obsolete.
Or maybe these homeowners willingly accept a period of aesthetic compromise as technology evolves and alleviates ugliness. Built-in air-conditioning systems were the antidote for unsightly apartment buildings with room air conditioners sticking out of windows, pockmarking building facades. Cable networks and satellites eliminated the need for unsightly TV antennas, too.
Technological innovation can make unattractive appurtenances disappear, which could be the solar panel’s eventual fate. Becoming more efficient, more compact and better camouflaged, they could appear to be roofing shingles, skylights or a new type of dormer.
Rooftop solar panels should be generally permitted as a matter of right, but subject to design guidelines. Compositionally integrating and harmonizing solar collectors with existing roof and facade designs, historic or otherwise, should be the principal goal of such guidelines.
Roger K. Lewis is a retired practicing architect, a University of Maryland professor emeritus of architecture and a guest commentator on WAMU’s “The Kojo Nnamdi Show.”