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Quantifying Shading’s Economic Impact

Photo courtesy SPG Solar

By: Paul Grana and Paul Gibbs

First published by by Solar Pro Issue 7.7 Nov/ Dec 2014

While it seems prudent to avoid array shading, an overconservative design approach may cost system owners and developers money. So how much shading can designers tolerate before the energy losses become a problem? The answer may surprise you.

Project developers and engineering firms typically approach array shading according to rules of thumb that are based on low tolerance for shade or that seek to avoid it altogether. For example, the system designer might eliminate modules if they are shaded during a specific window of time, or if they are located within a certain proximity to an obstruction. These conservative design approaches are largely based on assumptions that have lost their relevance.

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