Path-Q Solar
How much solar production would I lose if nearby trees shade the roof in the afternoon?
Answer
The loss could range from minor to substantial; it cannot be estimated reliably from the time of day alone. The result depends on which panels are shaded, how much of each panel is shaded, the shading duration and season, the array layout, and the system's electrical design. Afternoon shade is often more consequential when it overlaps the site's strongest production period, but the exact effect requires a site-specific shade analysis.
Key points
- Seasonal changes in sun angle and tree foliage can make annual loss different from a single-day observation.
- Shade on one module can affect a larger electrically connected group unless the design limits that effect.
- Module-level power electronics may reduce some mismatch effects but do not create energy where shade blocks sunlight.
- Tree growth and future trimming restrictions should be included in the assessment.
What it depends on
- Tree height, density, distance, and expected growth
- Roof orientation, panel placement, and array electrical configuration
- Time and season of shading
- Local solar path and available shade-model data
Risks and trade-offs
- Ignoring seasonal shade can cause an optimistic production estimate.
- Tree removal or trimming may have cost, environmental, ownership, or legal implications.
- Moving panels to avoid shade may reduce available roof area or increase design and installation complexity.
- Mitigation equipment can add cost without eliminating the underlying shade.
Information you may need
- Roof and tree measurements or clear site photographs
- Proposed panel layout and electrical design
- A full-year shade analysis rather than a single visual check
- Tree growth, maintenance, ownership, and trimming constraints
Your next step
What to do next
Ask for a documented annual shade analysis using the proposed layout and compare production with and without the affected roof sections.
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SQ01358