Working with a professional installer that uses an industry acceptable tool to locate solar electric modules where they will receive the most sun exposure is important to ensure you are maximizing your solar investment. Obstacle shading effect, expressed as a percentage, is the weighted effect of obstacle shading (including trees, power lines, buildings, etc.) on the annual production of the system. There are a variety of tools available including Solar Path Finder, SunEye 210’s Solmetric and Wiely Electronics ASSET. Focus on Energy does not make any recommendation or warranties related to tools available or their results.