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Design into Shade

 

Introduction

Traditionally shade is avoided when designing a solar array; however, using Smart Modules can mitigate the mismatch caused by shading. Shadows constantly change throughout the day and year, thus restricting how close any module can be placed to an obstruction. As little as one or two shaded modules can have a negative impact on the entire array. By creating module-level MPPT this effect is mitigated and shade becomes tolerable. The following section will provide a general process for determining how much shade can be designed into a system based on how much energy the Smart Modules can recuperate from potential mismatch losses.

 

Setback Distance in Traditional Arrays

In standard arrays the amount of space between any obstruction and the solar array (setback distance or holdout) is determined based on the sun chart for a particular region. The general guideline is that the setback distance should be three times the object height. Often, this means underutilized roof or ground space. With Tigo, this setback distance is reduced.

Setback with Tigo Optimizers and Smart Modules

The amount of shade you can design into your system is determined by how much energy a Smart Module can recuperate from mismatch. If 50% of the lost energy can be recuperated from a shaded module*, the percentage of annual impacted hours is reduced. 

 

The Setback Ratio Correlation to Annual Shade Impacted Hours

 

Referring to the chart above, we can calculate the effect of Tigo optimizers on the setback distance using the following equation:

 .14 (Percentage of annual hours impacted) x .50 (Percentage of lost energy recuperated)

x .75 (percentage of hours Tigo optimizers are mitigating shade in this particular installation)

Smart Modules provide the same percentage of affected hours as a standard array with only half of the setback ratio. While each system is different, you can assume your setback ratio can be reduced by approximately 50%.

 

Summary

  1. Tigo can reduce the setback distance of modules from an obstruction by approximately 50%. In many cases this may be more.
  2. Tigo Energy optimizers will enable modules that are always shaded throughout the day to produce whatever power is available from indirect light.

 *NREL tested and quantified that an average of 36% of power lost due to partial shading is recovered by Tigo optimizers.

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