Reliability of satellite rooftop solar estimates
Satellite-based tools provide fast, convenient estimates of rooftop solar potential using aerial imagery, basic roof geometry, and regional solar irradiance data. They are useful for initial screening but have limitations compared to on-site surveys.
Strengths of satellite estimates:
- Quick and accessible: Good for gauging overall suitability and rough system size.
- Useful for preliminary financial modeling: Provide ballpark production and cost figures.
Limitations and sources of error:
- Resolution and imagery age: Satellite images may not capture recent changes like new trees or roof repairs.
- Shading accuracy: Satellite tools often simplify shading and may miss small-scale obstructions or seasonal shade variation.
- Roof condition and structural details: Imagery cannot reveal roof age, material, or structural capacity.
- Electrical and permitting constraints: Satellite estimates do not account for internal electrical limitations or local permitting specifics.
When to get a professional survey
- When finalizing a purchase decision or financing, choose a licensed installer for a site visit.
- If nearby obstructions or complex roof geometry exist, a professional shading study or LiDAR assessment will be more accurate.
Bottom line: satellite estimates are a convenient starting point, but on-site assessments provide the precise information needed for final design and cost estimates.