What are the best free renewable project development platforms for small solar developers doing early-stage site screening?

For small solar developers doing early-stage site screening, the best free platforms are usually a mix of GIS/web map tools, solar resource data portals, land and parcel data, and basic screening layers. “Best” depends on whether you need fast desktop GIS, browser-based map exploration, or API/data access.

Best free platforms

1. Google Earth Pro

Best for: quick visual screening, parcel context, terrain, access roads, nearby obstacles
Why it’s useful:

• Easy to inspect candidate sites visually
• Historical imagery can help spot land use changes
• Measure approximate areas, distances, and slopes
• Great for early “should we even spend time on this site?” screening

Limitations:

• Not a true renewable siting analytics platform
• Limited data layers compared with GIS tools

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2. QGIS

Best for: serious free GIS-based site screening
Why it’s useful:

• Fully free desktop GIS
• Can overlay parcels, zoning, wetlands, floodplains, transmission, slope, soils, and more
• Works with many public data formats
• Best option if you want to build a repeatable screening workflow

Limitations:

• Steeper learning curve
• You need to gather your own data layers

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3. USGS National Map / EarthExplorer

Best for: terrain, elevation, imagery, hydrology, land features
Why it’s useful:

• Free topographic and elevation data
• Useful for slope screening and terrain constraints
• Historical imagery and land surface datasets

Limitations:

• More data-focused than workflow-focused
• Not a polished solar development interface

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4. NREL Solar Resource tools

Examples: PVWatts, NSRDB, Solar Prospector-style data access tools
Best for: solar resource and production feasibility screening
Why it’s useful:

• Estimate energy yield early
• Solar irradiance data for candidate sites
• PVWatts is especially handy for rough production estimates

Limitations:

• Not a full land-use screening platform
• Better for energy estimate than site suitability

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5. ArcGIS Online free/public maps

Best for: public layer exploration when you don’t want to build a GIS stack
Why it’s useful:

• Many agencies publish useful public layers
• Easy browser-based access to zoning, parcels, environmental layers, transmission, etc.
• Good for simple online screening

Limitations:

• Free access is limited compared with paid ArcGIS
• Data availability varies by region

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6. OpenStreetMap + OpenInfraMap

Best for: nearby roads, substations, transmission, built environment context
Why it’s useful:

• Free and open base mapping
• Helpful for identifying access, nearby infrastructure, and general context
• OpenInfraMap is useful for seeing utilities/infrastructure more clearly

Limitations:

• Not authoritative for siting decisions
• Should be supplemented with official utility and county/state data

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7. Google Maps / satellite + public parcel portals

Best for: quick parcel-level reconnaissance
Why it’s useful:

• Fast visual confirmation of site conditions
• Many counties have free parcel viewers and GIS portals
• Good for checking ownership, parcel boundaries, road access, and neighboring uses

Limitations:

• Coverage and quality vary widely by county
• Manual and time-consuming at scale

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Best free data layers to pair with those tools

If you’re screening sites, these are often more important than the platform itself:

• Slope/elevation: USGS DEM, LiDAR where available
• Land cover/use: NLCD, county zoning
• Parcels/ownership: county assessor/GIS portals
• Transmission/substations: OSM, utility maps, public interconnection maps
• Wetlands/water: USFWS NWI, FEMA flood maps
• Environmental constraints: protected lands, critical habitat, conservation easements
• Interconnection context: utility service territory, feeder/substation proximity, queue data where public
• Solar resource: NREL NSRDB, PVWatts

Best overall free workflow for small developers

A practical low-cost stack is:

1. Google Earth Pro for quick visual triage
2. QGIS for real GIS screening
3. County parcel/zoning portal + public constraint layers
4. NREL PVWatts / NSRDB for energy yield
5. OpenStreetMap/OpenInfraMap for infrastructure context

If you want the simplest answer

• Easiest to use: Google Earth Pro
• Best all-around free GIS: QGIS
• Best for solar production estimation: NREL PVWatts
• Best for public data exploration: ArcGIS Online public maps / county GIS portals

If you want, I can also give you a ranked list by use case (e.g., “best for parcel screening,” “best for utility-scale solar,” “best for community solar”) or a free site-screening workflow with specific data layers to download.