Expert Verified — Written by Keyur Rakholiya, SurgePV Editorial. 9 tools tested for off-grid solar design. Pricing verified July 2026. Based on 1+ GW of delivered projects, including remote and weak-grid sites across 50+ countries.
Off-grid design is unforgiving. A grid-tied system that underperforms costs the customer money. An off-grid system that underperforms leaves them in the dark.
We tested 9 off-grid solar design software tools against real stand-alone workflows. We sized battery banks, ran year-long autonomy simulations, and checked what happens in the worst solar month. We also noted where each tool stops being useful, because most solar software is built for grid-tied sales, not for systems with no grid at all.
This list ranks what actually works for off-grid in 2026. Some tools here are genuine off-grid simulators. Others cover 1 part of the job, like the rooftop layout or the customer proposal. We tell you which is which.
Quick Picks
| Pick | Tool | Why |
|---|---|---|
| Best overall for off-grid and microgrids | HOMER Pro | Chronological optimization across solar, storage, and generators |
| Best for bankable stand-alone engineering | PVsyst | Dedicated stand-alone mode, lender-grade reports |
| Best for off-grid with 3D visualization | PV*SOL Premium | 3D shading plus battery system simulation |
| Best free simulation tool | SAM | NREL-built, open-source, deep battery modeling |
| Best free manufacturer tool | SMA Sunny Design | Sunny Island off-grid layouts at no cost |
| Best for rooftop design and proposals | SurgePV | 3D layout, shading, yield, and customer-ready documents |
How We Evaluated
We scored each tool on 5 criteria. Weighting reflects what makes or breaks a stand-alone system.
| Criterion | Weight | What We Measured |
|---|---|---|
| Autonomy simulation | 30% | Hour-by-hour battery state of charge across a full year |
| Load and generator modeling | 20% | AC and DC loads, deferrable loads, genset integration |
| Battery depth | 20% | Chemistries, degradation, temperature effects, sizing logic |
| Design and layout tools | 15% | 3D modeling, shading analysis, electrical documentation |
| Cost and access | 15% | Price, free tiers, platform support, learning curve |
At-a-Glance Comparison
| Tool | Best For | Starting Price | True Off-Grid Simulation | Cloud | Standout |
|---|---|---|---|---|---|
| HOMER Pro | Off-grid and microgrids | $125/mo | Yes | No (Windows) | HOMER Optimizer tests thousands of configurations |
| PVsyst | Bankable engineering | ~$775/yr | Yes | No (Windows) | Stand-alone mode financiers accept |
| PV*SOL Premium | 3D off-grid design | €845/yr | Yes | No (Windows) | 3D shading plus 1,900+ battery models |
| SAM | Free hybrid simulation | $0 | Limited | No (desktop) | Open-source depth from NREL |
| SMA Sunny Design | SMA off-grid systems | $0 | Yes | Yes | Sunny Island sizing for free |
| SurgePV | Rooftop design + proposals | $1,899/yr (3 users) | No | Yes | Design-to-proposal in 1 workflow |
| BlueSol | Electrical design + CAD | ~$600/yr | Yes | No (Windows) | Stand-alone systems with full schematics |
| Photonik | Quick free sizing | $0 | Limited | Yes | Off-grid load calculator in the browser |
| OpenSolar | Selling storage-ready homes | $0 | No | Yes | Free CRM, proposals, and e-signature |
1. HOMER Pro — Best Off-Grid Design Software Overall
HOMER Pro, now owned by UL Solutions, is the reference tool for stand-alone and microgrid design. It reports 250,000+ users in 190+ countries, and it earned that position by doing 1 thing better than anyone else: chronological optimization of hybrid systems.
What It Does Well
The HOMER Optimizer tests thousands of system combinations against a full year of operation. Solar, wind, batteries, hydro, biomass, and diesel generators all model together in time steps from 1 minute to 1 hour. The output is the least-cost configuration that never drops the load.
That matters because off-grid sizing is a tradeoff. Oversize the battery and the project dies on cost. Undersize it and the lights go out in the worst month. HOMER quantifies that tradeoff instead of guessing it.
The NASA climate database covers any location on Earth. Sensitivity analysis stress-tests fuel prices, load growth, and solar resource uncertainty. Capterra reviewers rate HOMER 4.4 out of 5, and the package includes 2.5 hours of instructor-led training.
Our Take: If you design off-grid systems professionally, HOMER Pro pays for itself on the first project it rescues from a bad battery size. It has no layout tools, so pair it with a design platform for the physical work.
Where It Falls Short
There is no 3D modeling, no LIDAR, and no panel layout. HOMER sizes the system; it does not draw it. It runs on Windows only, the license is single-user, and the interface takes real effort to learn.
Key Features
- Chronological simulation at 1-minute to 1-hour steps
- Solar, wind, hydro, biomass, CHP, hydrogen, and generator support
- NASA global climate, solar, and wind data
- Sensitivity analysis for uncertain variables
Pricing
- HOMER Pro: From $125/month, add-on modules $6 to $15/month each
- HOMER QuickStart: Free simplified online tool for small systems
- Free trial: Available; academic pricing on request
Who Should Use HOMER Pro
Strong fit: Engineers, consultants, and developers designing off-grid, island, or microgrid systems of any size. Probably not right for: Residential sales teams, Mac users, and anyone wanting an all-in-one design tool.
2. PVsyst — Best Off-Grid Design Software for Bankable Engineering
PVsyst is the engineering standard behind financed solar projects. Its stand-alone mode is less famous than its grid-tied reports, but it handles off-grid battery systems and solar pumping with the same rigor.
What It Does Well
PVsyst models 4 system types: grid-connected, stand-alone, pumping, and DC-grid. The stand-alone module simulates battery state of charge through the year and reports the loss-of-load probability. That is the number a serious off-grid client or lender wants to see.
The component database runs deep, with 14,000+ modules and 4,500+ inverters. G2 reviewers rate PVsyst 4.5 out of 5 across 200+ reviews. Detailed loss modeling covers soiling, degradation, mismatch, and temperature.
For agricultural and water-pumping projects, PVsyst is often the only credible option. Isolated and battery-buffered pumping systems model directly, with water needs as the load profile.
Our Take: PVsyst is the right choice when the off-grid report itself is a deliverable, for a financier, a grant program, or an engineering review. It will not help you sell the system or lay it out.
Where It Falls Short
The interface is dated, and ease of use scores 7.1 out of 10 on G2. It is Windows-only with no cloud collaboration. There are no customer-facing proposals, and the learning curve is steep for occasional users.
Key Features
- Stand-alone and pumping system simulation
- Loss-of-load probability and autonomy analysis
- 14,000+ modules and 4,500+ inverters in the database
- Detailed loss, degradation, and temperature modeling
Pricing
- Professional: CHF 700/year (~$775), volume discounts from 2 licenses
- Free trial: 30 days, full features
Who Should Use PVsyst
Strong fit: Engineers and EPCs delivering financed or grant-funded off-grid and pumping projects. Probably not right for: Sales teams, quick residential sizing, and Mac users.
3. PV*SOL Premium — Best Off-Grid Design Software with 3D Visualization
PV*SOL Premium from Valentin Software combines real 3D shading analysis with battery system simulation. It is the strongest option when the off-grid design needs both physics and presentation.
What It Does Well
The 3D environment models shading module by module, hour by hour. CAD import accepts DXF, 3DS, and DAE files, and PhotoPlan builds rooftop geometry from photos. Most off-grid tools ignore shading entirely; PV*SOL treats it as a first-class input.
The battery database holds 1,900+ models alongside 21,000 modules and 5,100 inverters. Off-grid and battery-backed systems simulate with load profiles, and the financial layer covers NPV, IRR, payback, and 20-year lifecycle cost.
Reports generate in 24 languages with custom branding. For an installer presenting an off-grid design to a client or authority, the documentation quality is a genuine advantage.
Our Take: PV*SOL is the sweet spot when 1 tool must handle 3D layout, shading, batteries, and the client report. The 10,000-module cap and Windows-only architecture define its limits.
Where It Falls Short
It runs on Windows only, with no cloud or mobile version. Performance slows past 7,000 modules, and the 3D cap of 10,000 modules rules out large systems. Financial analysis scores 6.9 out of 10, well below PVsyst, and battery optimization is limited for complex dispatch strategies.
Key Features
- 3D shading analysis with CAD and PhotoPlan import
- 1,900+ batteries, 21,000 modules, 5,100 inverters
- Off-grid and battery storage simulation with load profiles
- Branded reports in 24 languages
Pricing
- PV*SOL Premium 2026: €845/year plus VAT
- PV*SOL Standard 2025: €585/year plus VAT
- PV*SOL Online: Free basic calculations, no 3D
- Free trial: 30 days, full features
Who Should Use PV*SOL Premium
Strong fit: Installers and engineers who need 3D shading, battery modeling, and polished reports in 1 desktop tool. Probably not right for: Large microgrids, Mac users, and teams needing cloud collaboration.
4. SAM — Best Free Off-Grid Simulation Software
The System Advisor Model (SAM) from the National Renewable Energy Laboratory (NREL) is free, open-source, and used by 150,000+ people in 190+ countries. For hybrid system analysis on a zero budget, nothing else comes close.
What It Does Well
SAM models photovoltaic systems with lithium-ion, lead-acid, and flow batteries. Front-of-meter and behind-the-meter configurations both work, and the financial models span residential, commercial, and utility ownership structures.
The depth is academic-grade because it is academic. NREL built SAM on the same simulation rigor that feeds its research. For a developer testing whether an off-grid concept is viable before paying for HOMER or PVsyst, SAM is the right first pass.
Scripting through SAM’s software development kit automates parametric runs. Researchers use it to sweep battery sizes, tilt angles, and load growth across thousands of scenarios.
Our Take: SAM is the best free way to pressure-test an off-grid concept. Budget real time for the learning curve, and verify its stand-alone battery logic against your use case before you trust the autonomy numbers.
Where It Falls Short
SAM’s focus is grid-connected and behind-the-meter economics. True stand-alone simulation is possible but less mature than HOMER or PVsyst. There is no layout or shading design, no proposals, and the interface assumes engineering literacy.
Key Features
- Free and open-source from NREL
- Lithium-ion, lead-acid, and flow battery models
- Techno-economic analysis across ownership structures
- Scripting and parametric analysis via SDK
Pricing
- SAM: $0, free and open-source
- Support: Community forums and NREL documentation
Who Should Use SAM
Strong fit: Researchers, students, and developers running feasibility studies on tight budgets. Probably not right for: Installers needing layout tools, proposals, or polished client output.
5. SMA Sunny Design — Best Free Off-Grid Design Software from a Manufacturer
Sunny Design is SMA’s free planning tool, and it covers the Sunny Island off-grid architecture that powers many of the world’s stand-alone systems. If your off-grid projects run on SMA hardware, this is the obvious starting point.
What It Does Well
The price is zero, with no license fees and no project caps. Sunny Design validates PV array, inverter, and battery combinations against SMA’s own device rules, which removes a whole class of sizing errors.
For off-grid work, it sizes Sunny Island battery systems, AC-coupled PV arrays, and backup generator integration. The web-based interface runs in a browser, so there is nothing to install and no Windows dependency.
Because SMA publishes it, the device database is always current for SMA equipment. New Sunny Island and Sunny Tripower firmware capabilities appear in the tool quickly.
Our Take: For SMA-based off-grid systems, Sunny Design is the fastest correct answer you can get for free. The moment a project mixes in other inverter brands, you need a brand-neutral tool alongside it.
Where It Falls Short
The tool assumes SMA hardware. Multi-brand designs are out of scope. Yield and financial analysis are lighter than PVsyst or HOMER, and there is no 3D shading or customer proposal output.
Key Features
- Free web-based planning for SMA systems
- Sunny Island off-grid and backup sizing
- Automatic device compatibility validation
- Generator and AC-coupling support
Pricing
- Sunny Design: $0, free from SMA
- Sunny Design Pro: Advanced features for registered professionals
Who Should Use SMA Sunny Design
Strong fit: Installers designing SMA-based off-grid, backup, and hybrid systems. Probably not right for: Multi-brand projects and bank-grade yield reporting.
Quote From Real Engineering Data
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6. SurgePV — Best for Rooftop Design and Proposals on Off-Grid Projects
Full disclosure: we build SurgePV. We ranked it #6 because it is not a stand-alone battery simulator, and this list is about honest fit. Where it earns its place is the physical and commercial side of off-grid work.
What It Does Well
Most off-grid projects still start on a roof. You need an accurate 3D layout, a shading study, and a realistic yield figure for the array before HOMER or PV*SOL sizes the storage. SurgePV handles that front end in the cloud.
Our solar design software builds 3D rooftop layouts with automated string sizing. The solar shadow analysis software runs physics-based shading hour by hour, so the array yield you hand to the battery sizing step is a real number, not a guess.
The generation and financial tool models payback, IRR, and NPV for the project. Branded PDF proposals turn the design into a customer-ready document, and Clara AI helps with the writing. For off-grid installers who lose deals on presentation, that closes the gap between engineering and sales.
Our Take: Use SurgePV for the array design, shading study, and proposal. Use HOMER, PVsyst, or SAM for the battery autonomy simulation. That pairing covers the full off-grid workflow without pretending 1 tool does everything.
Where It Falls Short
SurgePV does not simulate battery autonomy or loss-of-load probability. Off-grid battery bank sizing needs a dedicated simulator. There is no native CRM, no API, and no mobile app.
Key Features
- 3D rooftop design with layout and string sizing
- Physics-based shadow analysis
- Energy yield plus payback, IRR, and NPV
- Branded PDF proposals with Clara AI copy assistance
Pricing
- For 3 Users plan: $1,899/year, design, simulation, financials, and proposals included
- Free trial: Available with full design and proposal capabilities
Who Should Use SurgePV
Strong fit: Off-grid and hybrid installers who need professional rooftop design and proposals around their battery work. Probably not right for: Teams wanting battery autonomy simulation inside the design tool.
7. BlueSol — Best Off-Grid Design Software for Electrical Documentation
BlueSol, from Italian developer Sistemi Solari, supports stand-alone systems alongside grid-tied and storage configurations. Its strength is turning a design into complete electrical schematics.
What It Does Well
BlueSol models 4 system types: grid-connected, stand-alone, AC-coupled storage, and DC-coupled storage. The stand-alone mode sizes the battery bank against the load profile and checks autonomy.
The CAD layer is the differentiator. Single-line diagrams, cable sizing, and protection device selection generate from the design. For off-grid projects in markets that require full electrical documentation, BlueSol covers design through paperwork in 1 desktop application.
The 3D visualization and map-based layout tools handle the physical design side. Reports translate into multiple languages, which suits international project work.
Our Take: BlueSol is a practical pick when the deliverable includes electrical schematics, not just a yield report. Its simulation depth sits below HOMER and PVsyst, so treat its autonomy numbers as a starting estimate.
Where It Falls Short
It is Windows-only with a dated interface. The simulation engine lacks the chronological optimization depth of HOMER. International support and community resources are thinner than the market leaders.
Key Features
- Stand-alone, grid-tied, and storage system support
- Automatic single-line diagrams and cable sizing
- 3D visualization with map-based layout
- Multi-language reporting
Pricing
- BlueSol: From ~$600/year depending on configuration
- Free trial: 30 days
Who Should Use BlueSol
Strong fit: EPCs and installers who need electrical documentation for off-grid and storage projects. Probably not right for: Microgrid optimization work and Mac-based teams.
8. Photonik — Best Free Off-Grid Design Software for Quick Sizing
Photonik is a free, browser-based design platform that includes a dedicated off-grid load calculator. For fast early-stage sizing, it removes every barrier to entry.
What It Does Well
The off-grid load calculator walks you through daily consumption, then sizes array and battery against the location’s solar resource. It runs entirely in the browser, costs nothing, and needs no installation.
The broader platform covers panel placement optimization, shading analysis, and proposal generation. For a homeowner exploring off-grid or an installer doing a first-pass quote, the workflow is genuinely fast.
The electrification calculator adds value for rural and developing-market projects where the load itself is still being defined. That use case is common in off-grid work and rare in solar software.
Our Take: Photonik is the right tool for the first 30 minutes of an off-grid project. Graduate to HOMER or PVsyst before the design is final, because quick sizing is not year-long simulation.
Where It Falls Short
The off-grid modeling is a calculator, not a chronological simulator. There is no loss-of-load probability or multi-technology optimization. As a newer platform, its databases and advanced features trail the established tools.
Key Features
- Free browser-based off-grid load calculator
- Panel placement and shading tools
- Electrification calculator for rural projects
- Built-in proposal generation
Pricing
- Photonik: $0, free tier covers core design work
- Paid plans: Available for advanced features
Who Should Use Photonik
Strong fit: Homeowners, students, and installers doing quick feasibility sizing. Probably not right for: Final engineering on financed or mission-critical off-grid systems.
9. OpenSolar — Best for Selling Storage-Ready Residential Systems
OpenSolar is a free, full-featured solar sales platform used by 28,000+ professionals in 185+ countries. It is not an off-grid simulator. It earns the last spot because many “off-grid” residential deals are actually backup-storage deals, and OpenSolar sells those well.
What It Does Well
The price is $0 forever, with unlimited projects and users. Design, CRM, proposals, and e-signatures all come free, monetized through hardware and lending partners instead of installers.
Battery storage integrates into designs and proposals with backup scenario presentation. For homeowners who say “off-grid” but mean “I want power during outages,” OpenSolar’s interactive proposals close that conversation fast.
The built-in CRM and mobile apps cover the full sales loop. Most teams are operational in under 1 day, and accuracy is third-party validated.
Our Take: If your customer actually wants backup rather than true energy independence, OpenSolar is the best free way to design and sell it. For real stand-alone systems, the simulation depth is not there.
Where It Falls Short
There is no stand-alone autonomy simulation and no generator modeling. Systems cap around 500 kW, photogrammetry modeling trails LIDAR precision, and there is no offline mode.
Key Features
- Free design, CRM, proposals, and e-signature
- Battery storage and backup scenario modeling
- Interactive, mobile-friendly proposals
- iOS and Android apps
Pricing
- OpenSolar: $0, free forever with unlimited projects
- Free trial: Not needed; the product is free
Who Should Use OpenSolar
Strong fit: Residential installers selling battery backup and hybrid systems on a budget. Probably not right for: True off-grid engineering and C&I projects above 500 kW.
Decision Guide: Which Tool Fits Your Project
Match the project type to a shortlist before you download anything.
- Professional off-grid, island, or microgrid design: HOMER Pro. The optimization pays for itself in avoided oversizing.
- Financed or grant-funded stand-alone projects: PVsyst, paired with a proposal tool for the client-facing documents.
- Off-grid with serious shading and 3D needs: PV*SOL Premium.
- Feasibility study on a zero budget: SAM first, then HOMER or PVsyst for the final design.
- SMA-based off-grid systems: Sunny Design, free and hardware-validated.
- Rooftop layout, shading study, and customer proposal around the battery work: SurgePV, with a simulator for the autonomy side.
- Off-grid projects needing electrical schematics: BlueSol.
- Quick early-stage sizing: Photonik.
- Backup-storage residential sales: OpenSolar.
The Myth of the All-in-One Off-Grid Tool
Here is the contrarian truth: no tool on this list does the full off-grid workflow alone. The market splits into 3 layers, and pretending otherwise burns money.
The simulation layer (HOMER, PVsyst, SAM, PV*SOL) answers “will the lights stay on.” The design layer (SurgePV, BlueSol) answers “where does the hardware physically go and what does it look like.” The sales layer (OpenSolar, SurgePV) answers “will the customer sign.”
Grid-tied installers get away with 1 tool because the grid forgives design error. Off-grid has no forgiveness. A shading mistake that costs 8% of yield on a grid-tied roof becomes a dead battery in week 3 of a cloudy month off-grid. Budget for 2 tools: 1 that simulates autonomy, 1 that designs and sells the physical system.
How to Choose Off-Grid Design Software
Evaluate any tool against these 6 dimensions before you commit.
- Chronological simulation. If the tool does not track battery state of charge hour by hour for 8,760 hours, it is not an off-grid tool. Monthly averages hide the worst week.
- Loss-of-load reporting. Ask for the probability the system fails to meet the load. Serious tools report it. Calculators do not.
- Battery depth. Look for temperature effects, degradation, and multiple chemistries. A single generic battery model is a red flag.
- Generator and hybrid support. Most real off-grid systems include a genset. The tool should model fuel cost and runtime tradeoffs.
- Where shading comes from. Off-grid yield errors are fatal. Physics-based shading analysis beats a derate-factor guess.
- The deliverable. A lender wants a PVsyst report. A homeowner wants a clean proposal. A permit office wants schematics. Match the tool to the document.
Pro Tip
Run your worst-month scenario first, not your average month. If the tool cannot show you battery state of charge for the darkest 2 weeks of the year, it cannot design an off-grid system.
Conclusion
The right off-grid solar design software depends on which layer of the problem you own. HOMER Pro leads for professional stand-alone and microgrid design. PVsyst leads when the report must survive lender review. SAM and Sunny Design cover the free end with real depth. SurgePV covers the rooftop design, shading study, and proposal that every off-grid project still needs.
Every tool here has a defined ceiling, and we told you where it is. Three concrete next steps:
- Shortlist 1 simulator and 1 design tool from the decision guide, then run the same real project through both trials.
- Size your next off-grid battery bank in HOMER Pro or SAM and compare it against your rule-of-thumb estimate. The gap will surprise you.
- If your off-grid proposals lose deals on presentation, book a 20-minute SurgePV demo and test the design-to-proposal flow on a live project.
Where SurgePV fits
For the product-side detail, large-scale design in SurgePV covers the workflow, outputs and limits.
Frequently Asked Questions
What is off-grid solar design software?
Off-grid solar design software sizes and simulates stand-alone power systems with no utility grid connection. It models solar generation, battery storage, backup generators, and load profiles to prove the system can meet demand every day of the year.
What is the best free off-grid solar design software?
SAM from NREL is the most capable free option for hybrid system simulation. SMA Sunny Design is free and handles Sunny Island off-grid layouts well. Photonik offers a free off-grid load calculator for quick sizing.
Can Aurora Solar or HelioScope design off-grid systems?
No. Aurora Solar and HelioScope model grid-tied systems with backup storage, not true stand-alone systems. For off-grid work you need HOMER Pro, PVsyst, SAM, or PV*SOL, which simulate battery autonomy across a full year.
How do you size an off-grid solar system?
Start with a daily load audit in kilowatt-hours. Size the battery bank for 2 to 5 days of autonomy, then size the array to recharge it during the worst solar month. Software like HOMER Pro runs this chronologically, hour by hour, for 8,760 hours.
Is HOMER Pro worth the price?
For professional off-grid and microgrid work, yes. It is the industry standard with 250,000+ users, and its chronological optimization catches sizing errors that spreadsheet methods miss. For 1-off residential jobs, free tools like SAM may be enough.
What is the difference between off-grid and hybrid solar design?
Off-grid systems have no grid connection, so the battery and array must cover 100% of loads year-round. Hybrid systems stay grid-connected and use storage for backup or savings. Hybrid design tolerates error; off-grid design does not.
Related Posts
- Best Solar Design Software
- Best Solar Simulation Software
- Best Free Solar Design Software
- Off-Grid Solar System Sizing Calculator Guide
- Microgrid Design for Solar and Storage
For a deeper engineering walkthrough of stand-alone system design, see this complete guide to off-grid solar design from our sister team at Heaven Designs.
