Expert Verified — Written by Keyur Rakholiya, SurgePV Editorial. 10 free and free-trial tools tested for solar shadow analysis. Pricing verified July 2026. Based on 1+ GW of delivered projects across 50+ countries.
Shade is the number 1 silent killer of solar production promises. A chimney that throws a shadow at 4 PM in December can cut a string’s output far beyond its small footprint. Get the shading wrong, and your payback promise is wrong.
The good news: you do not need to pay $2,000 a year to model shadows. Several genuinely free tools handle real shading work, from quick raytraced roof models to open-source hourly simulation engines. We tested 10 of them against real project workflows.
This list ranks what actually works at $0, plus the free trials worth your time when free stops being enough. Every tool gets honest strengths and honest weaknesses, including our own.
Quick Picks
| Pick | Tool | Why |
|---|---|---|
| Best free all-in-one | OpenSolar | Real-time raytraced shading, $0 forever |
| Best free engineering engine | SAM (NREL) | Open source, hourly shading, P50/P90 |
| Best free validated simulation | SolarEdge Designer | DNV validated within 1% of PVsyst |
| Best free 3D shadow studies | SketchUp + Skelion | Visual shadow engine, PVsyst export |
| Best free trial for shading + proposals | SurgePV | Physics-based shading inside a full design workflow |
| Best free baseline estimator | PVWatts | Instant unshaded yield, NREL credibility |
How We Evaluated
We scored each tool on 5 criteria. Weighting reflects what matters when shade decides whether a design works.
| Criterion | Weight | What We Measured |
|---|---|---|
| Shading realism | 30% | 3D obstruction modeling, hourly resolution, beam vs diffuse |
| True cost | 25% | Free forever vs trial, feature gates, export limits |
| Ease of use | 20% | Time from address to shade result |
| Output quality | 15% | Reports, loss numbers, visuals a client can read |
| Upgrade path | 10% | What happens when the project outgrows free |
At-a-Glance Comparison
| Tool | Best For | Cost | Shading Method | Hourly | 3D | Standout |
|---|---|---|---|---|---|---|
| OpenSolar | Free all-in-one | $0 forever | Raytracing on 3D model | ✓ | ✓ | Full platform at no cost |
| SAM (NREL) | Engineering analysis | $0 forever | 3D shade scene + tables | ✓ | Limited | Open source, bankable-style depth |
| SolarEdge Designer | SolarEdge installs | $0 | Module-level simulation | ✓ | ✓ | Within 1% of PVsyst, DNV validated |
| SketchUp + Skelion | 3D shadow studies | Free tier + plugin | Real-time shadow engine | Limited | ✓ | Best visual shadow playback |
| SurgePV | Shading + proposals | Free trial, then $1,899/yr | Physics-based 3D shading | ✓ | ✓ | Shade data flows into yield and proposals |
| PV*SOL | Module-level shading | Free online + 30-day trial | Module-by-module, hour-by-hour | ✓ | ✓ | German engineering depth |
| PVsyst | Bankable reports | 30-day trial | 3D near-shading scene | ✓ | ✓ | The lender standard |
| Photonik | Australian installers | $0 | Shading analysis on aerial imagery | Limited | Limited | Free proposals included |
| Pylon | Low-volume quoting | 5 free projects | 3D shading analysis | ✓ | ✓ | Pay only when you quote |
| PVWatts | Unshaded baseline | $0 forever | None | — | — | NREL reference numbers in seconds |
1. OpenSolar — Best Free All-in-One Shadow Analysis
OpenSolar is the strongest fully free option we tested. It costs $0 forever, and 28,000+ users in 185+ countries run real shading work on it.
What It Does Well
The 3D design studio runs automatic shading analysis with real-time raytracing. You place obstructions, and shade impact updates as you drag panels. For a residential roof with trees and a chimney, you get a defensible production number in minutes.
Accuracy is third-party validated by PVEL and a US government agency, per OpenSolar. The platform wraps shading inside a full workflow: design, customer relationship management (CRM), proposals, and e-signatures, all free. Users report proposals in under 2 minutes once templates are set.
Our Take: If you pay for design software today and run projects under 500 kW, test OpenSolar first. The shading is good enough for residential quoting. It is not bank-grade, and it does not pretend to be.
Where It Falls Short
OpenSolar uses photogrammetry, not Light Detection and Ranging (LIDAR), so roof geometry is less precise than Aurora or HelioScope. The 500 kW cap in 3D rules out larger commercial work. There is no offline mode, and imagery resolution trails paid platforms.
Key Features
- Real-time raytraced shading on 3D roof models
- Automatic shading analysis with obstruction modeling
- Inverter stringing, batteries, and single-line diagrams
- Interactive proposals with e-signature, all free
Pricing
- Free tier: $0 — unlimited projects, unlimited users, all features
- Free trial: Not needed; the product is free
Who Should Use OpenSolar
Strong fit: Residential installers and small teams who need free, fast shading with a full sales workflow. Probably not right for: C&I above 500 kW, financed projects needing lender-grade reports, offline field work.
2. SAM — Best Free Engineering-Grade Shade Modeling
The System Advisor Model (SAM) is a free, open-source desktop simulator from the National Renewable Energy Laboratory (NREL). Over 150,000 users in 190+ countries use it, per NREL.
What It Does Well
SAM is the deepest free shading tool available. Its 3D shade calculator models near shading from buildings and trees, and the detailed photovoltaic (PV) model runs hourly, full-year simulation. P50 and P90 weather variability analysis is built in, which no other free tool offers.
Battery storage, financial models, and parametric studies come included. The component libraries cover real modules and inverters with manufacturer specifications. Because the code is open source since 2017, you can inspect exactly how the shading math works.
Our Take: SAM is what we recommend to engineers who need free and rigorous at the same time. Budget a week to learn it. The depth is real, and so is the learning curve.
Where It Falls Short
The interface feels like research software, because it is. Building a 3D shade scene takes manual work, and there is no imagery-based roof modeling at all. It produces engineering outputs, not customer-facing reports. Desktop only, no cloud collaboration.
Key Features
- 3D shade calculator with hourly beam and diffuse treatment
- Detailed PV model with manufacturer component libraries
- P50/P90 weather variability and Monte Carlo analysis
- Battery storage and financial modeling included
Pricing
- SAM: $0 — free and open source, commercial use permitted
- Registration: Free software key via email
Who Should Use SAM
Strong fit: Engineers, analysts, and researchers who need rigorous free shade and yield modeling. Probably not right for: Sales teams, quick residential quoting, and anyone unwilling to read documentation.
3. SolarEdge Designer — Best Free Validated Simulation for SolarEdge Installs
SolarEdge Designer is free for certified SolarEdge installers, and its accuracy claim is unusually strong for a $0 tool.
What It Does Well
DNV validated Designer’s energy estimates within 1% of PVsyst, with a slight conservative bias of -0.2%, according to the DNV validation report. That makes it the only free tool with lender-credible simulation behind it.
Automation is fast. Automatic roof detection, auto-stringing, and instant design validation cut setup time sharply. The tree shading feature lets you set exact tree dimensions, and designs sync into mySolarEdge for commissioning. Over 50,000 users have created 2.8 million layouts across 170+ countries.
Our Take: For SolarEdge-committed installers, Designer is the best free shading simulation on the market, full stop. The moment you spec another inverter brand, it stops being an option.
Where It Falls Short
Hardware lock-in is absolute: SolarEdge equipment only. Shading analysis is the most-cited weakness in user feedback, despite recent tree shading improvements. Only fixed-tilt systems are supported, and proposal output is minimal.
Key Features
- Module-level simulation within 1% of PVsyst
- Tree shading with exact obstruction dimensions
- Automatic roof detection and auto-stringing
- Direct sync with mySolarEdge commissioning
Pricing
- Designer: $0 — free for certified SolarEdge installers
- Free trial: Not needed; the product is free
Who Should Use SolarEdge Designer
Strong fit: Residential installers standardized on SolarEdge hardware. Probably not right for: Multi-brand shops, tracker projects, and complex shading sites.
4. SketchUp + Skelion — Best Free 3D Shadow Studies
SketchUp is a general 3D modeling platform, not solar software. Paired with the free Skelion plugin, it becomes the best free tool for visual shadow studies.
What It Does Well
SketchUp’s real-time shadow engine is excellent for sun-path analysis. You geolocate the site, model obstructions, and scrub through any hour of any day to watch shadows move. Kirloskar Solar validated SketchUp at 98% accuracy for site studies, per Trimble’s case study.
Skelion adds solar-specific tools: panel insertion on surfaces, tilt and azimuth control, and PVsyst export. The free SketchUp web version handles basic shadow studies at no cost. For customer presentations, nothing else on this list matches the visuals.
Our Take: SketchUp is our pick when the shadow question is visual: “show me what the tree does in winter.” It answers where shade falls, not how much energy you lose. Pair it with SAM or PVsyst for the numbers.
Where It Falls Short
SketchUp Free is web-only with basic features, and Skelion Free caps at 10 panels. There is no shading loss animation and no energy calculation in the free stack. Real workflows need SketchUp Pro at $349 per year plus Skelion Pro, so “free” runs out fast.
Key Features
- Real-time shadow engine with date and time scrubbing
- Geolocation and 3D terrain via satellite data
- Skelion plugin for panel layout and PVsyst export
- Offline capability on the desktop version
Pricing
- SketchUp Free: $0 — web-only, basic features
- Skelion Free: $0 — 10 panels maximum
- SketchUp Pro: $349/year — desktop plus web
Who Should Use SketchUp + Skelion
Strong fit: Designers who need visual shadow studies and client-ready 3D mockups. Probably not right for: Teams wanting energy loss numbers without a second tool.
5. SurgePV — Best Free Trial for Shading-to-Proposal Workflows
Full disclosure: we build SurgePV. We ranked it #5 because the product is paid after the trial, and this is a free-software list. For teams whose shade numbers must flow into yield, financials, and a client proposal, the trial is the fastest way to test that workflow.
What It Does Well
Most free tools answer 1 question: where does shade fall, or how much does it cost. SurgePV connects the whole chain. You design the 3D rooftop in the solar designing studio, then run the physics-based solar shadow analysis software. The same obstruction data feeds the generation and financial model. Payback, internal rate of return (IRR), and net present value (NPV) inherit the shading reality you modeled.
The branded proposal layer carries those numbers to the customer without re-typing. Clara AI assists with the copy. In our testing, a shaded residential roof goes from address to sendable proposal in under 15 minutes. The module and inverter database covers mainstream hardware.
Our Take: Free tools are fine until a shade error costs you a deal or a callback. SurgePV is the upgrade when shading accuracy has to survive engineering review and sales presentation in 1 platform.
Where It Falls Short
SurgePV is not free. After the trial, the plan is $1,899 per year for 3 users. There is no native CRM, and very large utility-scale work belongs in PVsyst or RatedPower. Teams wanting $0 forever should stay with OpenSolar or SAM.
Key Features
- 3D rooftop design with automated string sizing
- Physics-based shadow analysis on real obstruction geometry
- Energy yield plus payback, IRR, and NPV financials
- Branded PDF proposals built from live design data
Pricing
- For 3 Users plan: $1,899/year — design, shading, financials, and proposals included
- Free trial: Available with full design and shading capabilities
Who Should Use SurgePV
Strong fit: Installers and EPCs who need shade-accurate numbers from design through proposal, residential through commercial. Probably not right for: Hobbyists, one-off DIY projects, and teams committed to $0 software budgets.
Quote From Real Engineering Data
See how SurgePV turns design, shading, and financials into a customer-ready proposal in 1 workflow.
Book a DemoNo commitment required · 20 minutes · Live project walkthrough
6. PV*SOL — Best Free Trial for Module-Level 3D Shading
PVSOL from Valentin Software has modeled shading since 1998. The free PVSOL Online version handles basic calculations, and the Premium trial gives you 30 days of the full 3D engine.
What It Does Well
The shading simulation is module-by-module, hour-by-hour, across all 8,760 hours of the year. That granularity matters on complex roofs: dormers, multi-orientation arrays, and heavy obstruction environments. G2 comparative ratings score PV*SOL ease of use at 8.1 out of 10, well above PVsyst at 7.1.
The component database holds 21,000+ modules, 5,100+ inverters, and 1,900+ battery systems, per Valentin Software. Climate data comes from Meteonorm 9 with 8,300 stations. Reports are bankable and available in 24 languages.
Our Take: PVSOL is the gentlest path into engineering-grade shading. If PVsyst intimidates your team, run the 30-day PVSOL trial on your hardest shaded roof and compare outputs.
Where It Falls Short
PV*SOL Online, the permanently free version, has no 3D shading at all. The real engine is Windows-only desktop software at €845 per year. A 10,000-module cap in 3D rules out large utility-scale work, and financial analysis scores 6.9 out of 10, behind PVsyst.
Key Features
- Module-level 3D shading at hourly resolution
- 21,000+ modules and 5,100+ inverters in the database
- Meteonorm 9 climate data with 8,300 stations
- Battery, electric vehicle, and heat pump integration
Pricing
- PV*SOL Online: $0 — basic calculations, no 3D
- PV*SOL Premium: €845/year — full 3D shading engine
- Free trial: 30 days, full features (no report saving)
Who Should Use PV*SOL
Strong fit: Engineers and installers evaluating shading-heavy residential and commercial projects. Probably not right for: Mac users, utility-scale developers, and cloud-first teams.
7. PVsyst — Best Free Trial for Bankable Shade Reports
PVsyst is the reference standard for financed solar. Its 30-day free trial includes the full 3D near-shading scene builder, which makes it the best free window into bankable shading work.
What It Does Well
Lenders have trusted PVsyst reports for 30+ years. The 3D shading scene models near obstructions in detail, and the simulation engine computes hourly losses with P50, P90, P95, and P99 uncertainty bands. G2 reviewers rate its design and engineering depth at 9.4 out of 10.
The database covers 14,000+ modules and 4,500+ inverters. Version 8 adds unlimited orientations and sub-hourly clipping correction. For a project where a bank reads the shade report, nothing free substitutes for PVsyst. Our sister engineering team covers the workflow in detail in this guide on rooftop shadow analysis.
Our Take: Use the trial to learn the shading scene builder on a real project. If financed C&I is your market, PVsyst is not optional. It is the price of admission.
Where It Falls Short
Thirty days is all you get; after that it is CHF 700 per year. The interface is dated, ease of use scores 7.1 out of 10 on G2, and it runs on Windows only. There are no proposals, no CRM, and no cloud collaboration.
Key Features
- 3D near-shading scene with hourly loss computation
- P50/P90/P95/P99 bankable uncertainty analysis
- 14,000+ modules and 4,500+ inverters in the database
- Detailed loss modeling for soiling, degradation, and mismatch
Pricing
- Professional: CHF 700/year (~$775)
- Free trial: 30 days, full features
Who Should Use PVsyst
Strong fit: Engineers and developers on financed C&I or utility-scale projects. Probably not right for: Residential sales teams and anyone needing customer-facing output.
8. Photonik — Best Free Browser Tool for Australian Installers
Photonik is a free web-based design platform from Clean Energy Reviews in Australia. Every feature costs $0, permanently.
What It Does Well
The tool combines panel layout, shading analysis, and string voltage calculation in 1 browser tab. High-resolution aerial imagery comes standard, and proposals generate in about 2 minutes with return on investment (ROI) and payback math. Australian installers get a Small-scale Technology Certificate (STC) calculator built in.
User feedback on the Clean Energy Reviews forum is predominantly positive, praising ease of use and responsive development. For a new installer with zero software budget, it is a real starting point.
Our Take: Photonik is a genuine free option for residential quoting in Australia and beyond. Treat the shading output as feasibility-grade until the platform matures.
Where It Falls Short
Photonik has no G2 or Capterra presence, so independent validation is thin. The hardware database misses popular equipment like Enphase IQ8 and Sol-Ark hybrids, per user requests. There is no PDF export yet, and multi-inverter wiring support is limited.
Key Features
- Shading analysis with array optimization
- String voltage calculator for inverter matching
- Free proposal generation with ROI and payback
- STC calculator for the Australian market
Pricing
- Photonik: $0 — all features free, no paid tiers
- Free trial: Not needed; the product is free
Who Should Use Photonik
Strong fit: Australian residential installers and property owners planning systems. Probably not right for: Commercial projects, multi-inverter designs, and teams needing validated accuracy.
9. Pylon — Best Free Starter Projects for Low-Volume Quoting
Pylon (GetPylon) is an Australian-built design tool with pay-per-project pricing. The first 5 projects are free with no credit card, which earns it a place on this list.
What It Does Well
The 3D shading analysis won a Finder innovation award in 2021. Users report proposals in under 2 minutes, and the imagery-driven workflow needs almost no training. Over 3,500 solar businesses use it, per Pylon.
After the free projects, pricing is $4 per project with unlimited team users. For an installer quoting 10 projects a month, that is $40 in software costs, less than 1 hour of labor. One-click single-line diagrams and voltage rise reports come included.
Our Take: Pylon is the smartest economic model on this list for low-volume shops. The 5 free projects are a real evaluation window, not a crippled demo.
Where It Falls Short
After the free projects, it is paid, so it is not a $0-forever tool. Only 3 proposal templates limit branding, design variations cap at 5 per project, and imagery coverage has gaps in 10 to 20% of regions. Utility-scale work is out of scope.
Key Features
- Award-winning 3D shading analysis
- Pay-per-project pricing with unlimited users
- One-click single-line diagrams and voltage rise reports
- iPad-optimized for on-site design
Pricing
- Free trial: 5 free Standard projects, no credit card
- Standard: $4/project after trial
- Pro: $10/project — adds batteries and commercial features
Who Should Use Pylon
Strong fit: Small residential installers in Australia and the US with variable volume. Probably not right for: High-volume teams, C&I projects, and $0-forever budgets.
10. PVWatts — Best Free Baseline Yield Estimator
PVWatts is NREL’s free production calculator, running since 1999. It earns the last slot as the baseline tool, with 1 big caveat: it does not model shade at all.
What It Does Well
Speed and credibility. Enter an address, system size, tilt, and azimuth. You get monthly and annual production in seconds, built on 30 years of weather data from the National Solar Radiation Database. Version 5 improved annual accuracy to within about 2% of measured output for unshaded systems, per NREL.
A free application programming interface (API) lets other tools embed PVWatts, and many commercial platforms do exactly that. For a homeowner sanity check or a first-pass feasibility screen, it is the industry default.
Our Take: PVWatts gives you the ceiling, not the reality. Run it for the unshaded number, then subtract what a real shading tool measures. Never quote a shaded roof from PVWatts alone.
Where It Falls Short
There is no obstruction modeling: no trees, no buildings, no parapets. You can only nudge a generic loss percentage by hand. NREL states errors can reach ±10% annually and ±30% monthly. No 3D, no component database, no financials, no reports.
Key Features
- Instant production estimates from address input
- 30 years of NSRDB weather data
- Bifacial support in Version 8
- Free API for developers
Pricing
- PVWatts: $0 — no registration, no limits
- API: Free with an NREL developer key
Who Should Use PVWatts
Strong fit: Homeowners, students, and professionals needing a fast unshaded baseline. Probably not right for: Any site with shading, which is most roofs.
Decision Flowchart: Which Free Tool Fits Your Situation
Match your project to a starting point before you download anything.
- Residential installer needing free design plus shading plus proposals: OpenSolar. Nothing else free covers the full loop.
- Engineer needing rigorous free shade and yield modeling: SAM. Open source, hourly, P50/P90.
- SolarEdge-committed installer: SolarEdge Designer. Free and DNV validated.
- Visual shadow question for a client or permit board: SketchUp with Skelion. Show the shadow, then quantify elsewhere.
- Shade numbers that must flow into financials and proposals: SurgePV trial. Test the connected workflow.
- Complex shaded roof needing engineering-grade proof: PVSOL or PVsyst trial. PVSOL for usability, PVsyst for the bank.
- Australian residential installer on a zero budget: Photonik, then Pylon when volume grows.
- Unshaded feasibility check in 60 seconds: PVWatts.
The Myth That Free Shading Software Is Good Enough for Everything
Here is the contrarian truth: for a large share of residential work, free tools are not the compromise. They are the right answer. OpenSolar’s raytracing handles a typical suburban roof fine. SAM handles the engineering math fine. Paying $200 a month does not make a chimney shadow bigger or smaller.
The myth cuts the other way too. Free tools share 3 blind spots: imagery quality, validation depth, and accountability. When a financed project’s debt sizing depends on a P90 shade number, a free tool’s output carries no weight with a lender. When a customer disputes production in month 6, “the free app said so” is not a defense.
Our rule from 1+ GW of delivered projects: use free tools until shade losses decide real money. The moment a 3% production error changes a payback promise, a loan covenant, or a warranty obligation, pay for validated shading. For a broader view of paid options, see our best solar shading analysis software ranking and our guide to how shading affects solar panels. Teams comparing full platforms beyond shading can start with our solar software overview and our best solar design software list.
How to Choose Free Shadow Analysis Software
Evaluate any tool against these 6 checks before you trust its numbers.
- Hourly or snapshot? Full-year hourly simulation catches seasonal shadows. A single sun-path image misses December entirely.
- 3D obstructions or loss percentages? Real geometry beats a guessed 10% shade derate every time.
- Beam and diffuse treatment. Good tools separate direct from diffuse irradiance losses. Basic ones treat all shade as total loss.
- Validation. Look for third-party checks: DNV, PVEL, or comparison against PVsyst. “Industry-observed ranges” are not validation.
- What happens to the number next. A shade result that cannot flow into yield, financials, or a proposal creates manual re-entry errors.
- The real price of free. Trials end, plugins cap at 10 panels, and free tiers gate exports. Price the workflow at your real volume.
Pro Tip
Take your 3 most recent shaded installs and rerun them in 2 free tools plus 1 trial. If all 3 shade estimates land within 3% of each other, trust the free stack. If they diverge, your sites need a paid validated engine.
Conclusion
Free shadow analysis software is genuinely good in 2026. OpenSolar covers residential design and shading at $0. SAM delivers engineering-grade hourly modeling for nothing. SolarEdge Designer brings DNV-validated accuracy to SolarEdge shops. The gaps appear at the edges: financed projects, dense urban roofs, and workflows where shade numbers must reach a proposal untouched.
3 concrete next steps:
- Run your hardest shaded roof through OpenSolar and SAM this week. Compare the shade loss numbers against your actual production data.
- Test the SurgePV trial on 1 live quote to see shading, yield, and proposal in 1 workflow before your next busy season.
- Set a trigger rule for your team: any financed project, or any site where modeled shade loss exceeds 15%, gets a PVsyst or PV*SOL report.
If you want to see how SurgePV connects shading to yield and proposals, book a 20-minute demo.
Frequently Asked Questions
What is the best free shadow analysis software for solar?
OpenSolar is the best fully free option, with real-time raytraced shading on 3D roof models. For engineering-grade shade modeling, NREL’s System Advisor Model (SAM) is free and open source. Both cost $0 forever.
Is free solar shading software accurate enough?
For residential feasibility and quoting, yes. Tools like SolarEdge Designer are DNV validated within 1% of PVsyst. For financed commercial projects, lenders still expect PVsyst or PV*SOL reports, so free tools work for screening, not final diligence.
What is 8760-hour shadow analysis?
It models shade impact for every hour of the year, all 8,760 hours, across seasons and sun angles. This catches winter parapet shadows and morning tree shade that a single sun-path snapshot misses. SAM, PVsyst, PV*SOL, and SurgePV all use full-year hourly methods.
Can PVWatts do shadow analysis?
No. PVWatts is a production estimator from NREL with no obstruction modeling. You can only adjust a generic loss percentage manually. Use it for an unshaded baseline, then model shading in OpenSolar, SAM, or SketchUp.
What is the difference between near shading and far shading?
Near shading comes from objects on or close to the array, like parapets, vents, trees, and adjacent buildings. Far shading is the horizon profile, like distant hills. Good tools model near shading in 3D and import horizon data separately.
When should I upgrade from free shadow analysis software to a paid tool?
Upgrade when shade losses decide money: financed C&I projects, dense urban roofs, or any quote where a 3% production error changes the payback promise. Paid tools add validated engines, bankable reports, and faster 3D workflows.
