SolarScope vs Google Project Sunroof: Complete 2026 Comparison
Professional AI solar analysis vs a free homeowner estimate tool — not really the same category.
Overview
Google Project Sunroof launched in 2015 as a consumer awareness tool using Google Maps satellite imagery and 3D roof modeling to estimate solar potential for residential rooftops. It provides homeowners with a simplified estimate of panel area, annual sunlight hours, estimated savings, and local installer recommendations. Coverage is limited to select US metropolitan areas with sufficient Google imagery data. The service is free.
SolarScope is a professional AI solar analysis platform designed for solar developers, consultants, and installers. It uses NREL's National Solar Radiation Database (NSRDB) and NASA POWER API for irradiance data, a GPT-4o AI assistant for site interpretation, and map layers for grid hosting capacity, FEMA flood zones, and infrastructure data. It supports residential through utility-scale projects and is priced at $99–299/year.
Key Differences at a Glance
| Aspect | SolarScope | Google Project Sunroof |
|---|---|---|
| Target User | Solar professionals (developers, consultants, installers) | Homeowners exploring rooftop solar |
| AI Assistant | ✓ GPT-4o with site-specific analysis | ❌ None |
| Irradiance Data Source | NREL NSRDB + NASA POWER | Google satellite + weather estimates |
| Coverage | Full US + international (via NASA) | Limited US metro areas only |
| Project Scale | Residential to utility-scale | Residential rooftop only |
| Grid Infrastructure Data | ✓ Hosting capacity, transmission lines | ❌ Not included |
| Custom System Parameters | ✓ Full customization (kW, tilt, financials) | Limited (basic slider) |
| Annual Cost | $99–299/year | Free |
Who Should Use Each Tool?
Use Google Project Sunroof if:
- You're a homeowner wanting a quick, zero-effort first estimate
- You want to understand roughly how much roof area is suitable for solar
- You want to find local solar installers through Google's directory
- You live in a covered metropolitan area
- You don't need professional-grade analysis for commercial decisions
Use SolarScope if:
- You're a solar professional needing accurate, defensible analysis
- You're evaluating commercial, industrial, or utility-scale sites
- You need NREL or NASA irradiance data for professional reports
- You want AI-assisted analysis and interpretation of site data
- You need grid connectivity, flood zone, or environmental analysis
- Your site isn't covered by Google Sunroof's limited metro coverage
Feature Comparison
| Feature | SolarScope | Google Project Sunroof |
|---|---|---|
| AI Solar Analysis | ✓ GPT-4o AI assistant | ❌ None |
| NREL Irradiance Data | ✓ NSRDB via API | ❌ Google proprietary estimate |
| Commercial/C&I Support | ✓ All scales supported | ❌ Residential only |
| Grid Hosting Capacity | ✓ ArcGIS Living Atlas integration | ❌ Not available |
| Flood Zone Analysis | ✓ FEMA data integrated | ❌ Not available |
| Geographic Coverage | All US + international | Limited US metro areas |
| Financial Modeling | ✓ ITC, payback, NPV customizable | Basic savings estimate |
| Project History / Saving | ✓ Project management included | ❌ No project saving |
| Monthly GHI Data | ✓ Monthly breakdown by location | Annual estimate only |
| API Access | ✓ Planned for Pro tier | ❌ Not available |
Accuracy: NREL Data vs Google Satellite Estimates
The data sources underlying each tool produce significantly different levels of accuracy for professional use:
NREL NSRDB (used by SolarScope) is the US government's gold-standard solar resource dataset. It's derived from GOES satellite imagery processed through validated physical models at 4 km × 4 km resolution for the full US, updated annually. It's the same dataset used by PVsyst, SAM, and other professional simulation tools, and is accepted for project financing.
Google Project Sunroof uses Google Maps 3D imagery to estimate roof tilt and shading, combined with general regional weather data to produce a simplified irradiance estimate. It's useful for a ballpark residential estimate but not calibrated to the standards required for professional analysis or project financing.
Frequently Asked Questions
Is Google Sunroof accurate enough for a professional project evaluation?
No. For professional solar project evaluation, NREL NSRDB data (used by SolarScope) provides significantly more accurate irradiance data validated against ground measurements. Google Sunroof's estimates are useful for homeowner awareness but should not be used for financial analysis in a professional context.
Why doesn't Google Sunroof cover my address?
Google Project Sunroof requires high-quality 3D imagery that Google has only processed for major US metropolitan areas. Rural areas, smaller cities, and international locations are not covered. SolarScope uses NREL satellite-derived data that covers all US locations at 4km resolution, with no coverage gaps.
Can a homeowner use SolarScope instead of Google Sunroof?
Yes. SolarScope's free tier provides location-specific NREL irradiance data, AI-guided analysis, and production estimates that are more accurate than Google Sunroof's consumer tool. Homeowners who want authoritative data before speaking to an installer will find SolarScope's analysis more credible and detailed.
Does Google Sunroof work for ground-mount commercial solar?
No. Google Project Sunroof is designed exclusively for rooftop estimates and has no functionality for commercial ground-mount, carport, or utility-scale analysis. SolarScope supports any project type at any location with customizable system parameters from 5 kW to 5 MW+.
Is SolarScope better than Google Sunroof?
For professional solar analysis, yes — SolarScope is significantly more capable, accurate, and flexible. For a homeowner needing a 30-second ballpark estimate on a covered address, Google Sunroof's simplicity and zero cost may be sufficient as a first step before contacting an installer.
The Bottom Line
Google Project Sunroof is a useful consumer awareness tool that gets homeowners thinking about solar. It's free, easy to use, and works for basic residential estimates in covered metro areas.
SolarScope is what solar professionals actually use. NREL and NASA irradiance data, AI-guided analysis, commercial and utility-scale support, grid infrastructure data, and full financial modeling — at $99/year, it delivers professional results that a consumer tool like Google Sunroof simply cannot provide.
If you're a solar professional, a consultant, or a homeowner who wants accurate analysis rather than a rough estimate, SolarScope is the right choice.
Try SolarScope Free
Professional AI-powered solar analysis with NREL data. Better than Sunroof for any serious analysis.
Works for any US location. No coverage gaps.