Trees or Solar Panels, Do You Have to Choose?

In one corner, we have trees. In the other, solar panels. Which one will win in America’s cities? Should we prioritize the urban canopy, or open up spaces to harvest sun power? Well, as Portland certified arborists, we don’t think this has to be a fight. While homeowners may feel they must choose between solar panels and trees, we have found it is possible for both to coexist effectively. Homeowners from Washington DC to San Jose have fought or even sued over solar access, oftentimes with two environmentally conscious neighbors battling over who has the ecological upper ground. However, as we outline below, proper tree placement and pruning can allow solar panels to function in proximity to shade trees.

There’s no denying that solar panels do not operate as well under shade. A Renewable Energy Laboratory study found that shadows over PV (photovoltaic) panels reduce power production by one third. Researchers are aware of the problem, and are looking for ways to boost productivity in shady conditions. The National Renewable Energy Laboratory recently found a way to increase productivity under shade by 12%, by using microinverters instead of string inverters within PV panels.

In some parts of the country, the solar panel vs. tree debate has spurred legal battles and legislation. For example, California’s Solar Shade Act was passed in 1978 to protect homeowners’ investments in solar energy. The law made it a crime to impede panels’ sun access. In 2008, a couple in Sunnyvale, California was convicted on criminal charges that their backyard redwood trees blocked their neighbor’s PV panels. In response, state Senator Joe Simitian passed a bill protecting pre-existing trees, so that homeowners cannot be prosecuted for planting trees prior to the installation of neighbors’ solar panels.

Here in Oregon, there is no solar access law protecting solar panel owners from similar situations. For property owners in Portland, tree services cannot be court-ordered to protect solar access. However, homeowners can request voluntary easements asking neighbors to maintain sunshine availability. That’s the first step in achieving tree- and solar-friendly boroughs: open and respectful communication between neighbors. Here are a few more techniques for preserving both solar access and healthy tree growth.

Portland Certified Arborists’ Tips For Tree Care with Solar Panels
• Place trees away from home to prevent blocking, scratching, and otherwise damaging solar panels.
• Avoid planting trees near the west or southwestern facing sides of home; these directions receive the strongest sunlight and are the best options for solar panel placement.
• Properly maintain trees that are already planted, to prevent solar panel damage. Regular Portland tree trimming will minimize neighbor disputes and protect PV panels.
• Remove dying trees, which pose a threat to nearby structures including solar-paneled roofs. Portland tree removal is recommended for unstable, unhealthy trees.

If you have questions about a certain tree on your property, get in touch. We can provide recommendations on how to enjoy both solar energy and vibrantly healthy trees. Our ISA certified arborists are happy to answer your Portland tree planting questions. We can calculate sunlight angles onto PV panels, according to each specimen’s mature height. Our arborists can also provide recommendations on the best tree placement for solar panels. Call us today for more information on how to balance shade with solar access.