What are the best free site energy system integrators for an early-stage storage feasibility review?

For an early-stage site energy storage feasibility review, the “best” free tools are usually the ones that can quickly estimate load shape, PV + storage interactions, tariffs, and utility bill savings without a lot of setup. If you mean site energy system integrators in the sense of software/tools that combine site data and help size storage, here are the strongest free options:

Good free tools / platforms

1. NREL REopt Lite

   • Best for: quick techno-economic screening of PV + storage + backup generator options
   • Strengths: strong optimization engine, easy web interface, widely trusted
   • Limitations: more high-level than detailed engineering; needs decent input data

2. NREL SAM (System Advisor Model)

   • Best for: more detailed project screening and financial modeling
   • Strengths: free desktop software, robust PV and storage modeling, strong credibility
   • Limitations: steeper learning curve; not as quick for a first-pass feasibility check

3. DOE/OpenEI Utility Rate Database + rate tools

   • Best for: checking tariff structures and demand charges
   • Strengths: free tariff data, useful for storage economics
   • Limitations: not a full integrator by itself

4. HOMER Pro trial / HOMER Grid demos

   • Best for: microgrid and storage hybrid screening
   • Strengths: very strong for system sizing and dispatch logic
   • Limitations: full functionality is not free; demos/trials may be limited

5. PVWatts + simple storage spreadsheet

   • Best for: very early “is this worth exploring?” checks
   • Strengths: easy, fast, free, good enough for rough PV generation estimates
   • Limitations: not a true storage optimizer unless paired with your own spreadsheet model

6. Energy Toolbase demo / partner access

   • Best for: site bill savings analysis and storage tariff optimization
   • Strengths: practical for commercial sites
   • Limitations: typically not fully free; availability depends on access

7. Aurora / HelioScope trials

   • Best for: PV-first projects where storage is secondary
   • Strengths: good site modeling and layout tools
   • Limitations: storage analysis is usually limited without paid access

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If you want the shortest answer

For a free early-stage storage feasibility review, I’d start with:

• REopt Lite for optimization/sizing
• SAM for more detailed modeling
• Utility rate database / tariff analysis for savings potential
• PVWatts for quick generation assumptions

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What to choose by use case

• Commercial behind-the-meter storage: REopt Lite, SAM
• Microgrid / resilience study: REopt Lite, HOMER (trial if available)
• PV + battery preliminary economics: SAM, PVWatts + spreadsheet
• Tariff-driven savings analysis: REopt Lite + utility tariff data

If you want, I can also give you:

1. a ranked list by ease of use,
2. a free-only workflow, or
3. a comparison table for commercial battery feasibility.