Zoning Practice — November 2010

Ask the Author

Brian RossSuzanne Sutro Rhees, AICPHere are reader questions answered by Brian Ross and Suzanne Sutro Rhees, AICP, authors of the November 2010 Zoning Practice article "Solar Energy and Land-Use Regulation."

Question from Audrey Whetten, Manteo, North Carolina:

Manteo's residential and commercial town center is zoned as a historic district. The historical review board was recently asked about the possibility of installing solar panels (both PV and solar thermal) on a historic structure in the historic district. The town planner sought advice from other planners statewide, but received no definitive assistance. Both goals — historic preservation and alternative energy sources — are commendable, but difficult to reconcile. Do you have recommendations on the subject? Has a precedent been set?

Answer from author Suzanne Sutro Rhees, AICP:

Most solar advocates recognize that installations are not appropriate everywhere and that introducing solar installations in historic districts can present the greatest design challenges. Many cities that encourage solar installations retain the authority to review any installation for appropriateness on a historic building or within a historic district. Portland, for example, requires design review of solar installations in a design zone, historic district, or on a historic landmark. Design review is a discretionary review that requires a public notice and generally takes about eight weeks to complete. 

Some design recommendations for historic buildings might include panels flush with the roof or placement on an accessory structure rather than the main building. But obviously, the right solar exposure may not be the least visible one.

Answer from author Brian Ross:

Generally, solar retrofits are still relatively unusual, and historic buildings are a small enough portion of our existing buildings stock, that you would think the intersection of these two would be small enough as to be insignificant. However, it comes up with surprising frequency.

I am of the opinion that historic buildings (landmarks) are simply unsuitable candidates for solar retrofits, unless the installation can be on the grounds rather than on the building. We should focus on means of making these buildings energy efficient within the context of their historic assets rather than trying to leverage a solar system into the design requirements.

Other categories of historic designation (like a district) should provide some opportunities for solar if the installation can be kept out of view of the front public right-of-way, keeping in mind that "opportunity" to incorporate solar does not mean a "right" in incorporate solar. Some communities have discussed forbidding solar on the front right-of-way in all cases (which I believe to be overly restrictive) but in a historic district it makes some sense.

Question from Mike Kraemer, Pitkin County, Colorado:

I'm a planner with Pitkin County, and we are currently rewriting our Land Use Code to address solar panel development and are getting hung up on how to address the neighborhood impact of panel glare. I have extensively researched what other jurisdictions are doing and can't find much. I'm wondering if you had any info worth passing along.

Answer from author Brian Ross:

Virtually all solar panels use low-glare glass — it's in the manufacturer's interest to capture as much of the sunlight as they can. Furthermore, nearly all panels have an anti-reflective coating to limit this issue. Finally, the angle of the panel usually mitigates for the light that is reflected (the reflected light is too high to affect other land uses or viewsheds.

However, there have been some instances when the panel results in glare that has created a stir. Ground mounted panels with a steep elevation where the southern land uses are on higher land can result in a nuisance, although the glare would be only for a short time and only during some times of the year. These are usually pretty unique circumstances, but perhaps you have one in your community.

A couple of local governments did require a "glare study" to be done when people protested. I do not know of any specific language on glare that has been incorporated into a solar ordinance. But glare is addressed in ordinances for other reasons, and I would imagine that such language could be incorporated into a solar ordinance. The government could certainly require panels with anti-reflective coatings and that the installation should work with the angle of panel elevation and location of panel to minimize potential for glare.

For the most part, glare from solar panels is really no different than glare from large windows. There are some technical resources on glare on the web, usually describing why glare should not be a problem ...