Path-Q Solar

How much shade is too much for rooftop solar?

Answer

There is no universal cutoff: solar may remain worthwhile with some shade, but the answer depends on how much energy is lost, when the shade occurs, whether it affects one panel or a larger area, and the value of the electricity produced. A shade study should quantify annual and seasonal production rather than relying on a visual judgment.

Key points

  • Short-duration or limited-area shade may be manageable.
  • Shade during high-production periods can reduce output more than shade during low-production periods.
  • Trees and nearby structures can create changing shade as the sun moves and seasons change.
  • The system may be redesigned around shaded areas rather than rejecting the whole roof.

What it depends on

  • Timing, duration, and extent of shade
  • Roof orientation and pitch
  • Panel layout and electrical configuration
  • Electricity value and expected system costs
  • Future growth of trees or nearby obstructions

Risks and trade-offs

  • Ignoring shade can lead to overstated production and savings estimates.
  • Shade-mitigation equipment may add cost and complexity without eliminating the underlying shade.
  • Removing vegetation may create environmental, privacy, or property risks.

Information you may need

  • A year-round shade assessment
  • The proposed panel layout
  • Annual electricity use and applicable bill structure
  • The expected production with and without shaded roof areas

Your next step

What to do next

Obtain a shade report showing projected production by roof section and ask whether shaded areas should be excluded from the design.

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