Most municipalities do not have ordinances in place to limit the location and height of trees being planted on one lot which neighbors another with the installation of photovoltaic panels. In fact, most promote planting and reforestation of lots.
- Oak trees grow at a rate of 1-2 feet per year and can grow up to 60-100 feet in height, with upwards of a 100-ft-diameter canopy.
- If the trees are being planted 4 feet from the property line, this will not only adversely affect the PV system but will require more yard maintenance on your property, such as leaf cleanup and branch trimming.
What you can do
Here are a few things you can do to determine what effect the trees will have on your PV array:
View the solar charts for your location. These charts are based on longitude and will show the position of the sun throughout the course of a year, including its relative angle to the surface of the earth.
- Using this information, analyze the position of the sun for each of the equinoxes and solstices; this will give you a good base of data.
- With the data (especially the sun's angle) gathered from the charts, you can analyze the shadow patterns produced by the trees and assess at which point in height they will negatively affect your ability to produce electricity. For example, an 80-foot tree with a 60-ft-diameter canopy at a solar angle of 74 degrees will produce a shadow extending +/- 45 feet onto your lot.
Another powerful tool in determining the shadow patterns is to model your home, garage, and neighboring trees in a 3D modeling program such as Sketch-up.
- If you are unable to do this on your own, try contacting your local high school or university with an architectural program and ask if any students would be willing to assist you in your research.
- From your 3D rendering, you will be able to view all shadows produced at any given month, week, day and time.
You can also print these models and use them as tools to explain to your neighbor what effect his/her trees will have in the future on your solar power. Hopefully this will convince them to rethink their location for planting.
Meet with planning officials
I would also recommend that you meet with your municipality's planning official to review your renderings.
I believe that they can be a useful tool to rectify your situation as well as help your municipality's building and planning officials to work toward a comprehensive and viable ordinance which helps promote renewable energy systems and reforestation of our beloved Earth.