The Sun Number Score was once a popular tool for quickly estimating a home’s solar potential, though its availability and role have shifted in recent years. Sun Number scoring assessed roof orientation, shading, and size on a 0-100 scale, but Zillow discontinued its integration, shifting homeowners toward alternative tools.
Sun Number Score Basics
| Score Range | Solar Suitability |
|---|---|
| 80-100 | Excellent solar potential |
| 60-79 | Good solar potential |
| 40-59 | Fair — worth professional assessment |
| Below 40 | Limited potential, likely shading/orientation issues |
How Sun Number Scoring Worked
The methodology analyzed roof orientation, tilt, shading from trees and nearby structures, and available roof area to generate a 0-100 score estimating solar suitability without a site visit.
The Zillow Discontinuation
Zillow discontinued its Sun Number integration, reducing the tool’s visibility and prominence in the home-buying and solar research process compared to its earlier widespread use.
Alternative Tools Today
Google’s Project Sunroof and direct assessments through solar installers using tools like PVWatts and Aurora Solar provide similarly accessible ways to estimate solar potential today.
Why a Professional Assessment Still Matters
Any automated scoring tool provides a useful starting estimate, but a professional site assessment remains the gold standard for accurate sizing and installation planning.
Get a professional solar assessment for your home: (855) 427-0058
Frequently Asked Questions
What was the Sun Number Score?
A 0-100 scale estimating a home’s solar suitability based on roof characteristics.
Is Sun Number still available on Zillow?
No — Zillow discontinued this integration.
What tools can I use instead of Sun Number?
Google’s Project Sunroof and professional installer assessments using PVWatts or Aurora Solar.
How accurate were Sun Number scores?
Useful as a starting estimate, but less accurate than a professional site assessment.
What made up a Sun Number score?
Roof orientation, tilt, shading, and available roof area.
Should I still rely on automated scoring tools?
Use them as a starting point, but get a professional assessment before committing.
What score range indicated good solar potential?
Generally 60 and above indicated good to excellent solar suitability.
Summing Up
While Sun Number scoring has largely faded, professional assessment remains the best way to evaluate solar potential. For a professional assessment, call (855) 427-0058 or visit us.solarpanelsnetwork.com.
Updated