You are looking for free solar design software because you are starting out, testing the market, or running fewer than five deals a month. The good news: in 2026 there are genuine free options. The catch: every "free" tool has a scaling limit, and the limit hits faster than installers expect. So you need to know which free tool fits your stage and when to upgrade.
This guide covers four free options (OpenSolar, SAM/NREL, PVWatts, SurgePV trial) plus the conversion math that tells you when free stops being cheap.
Key takeaway. OpenSolar's free tier works under 5 sub-10 kW residential deals a month. SAM and PVWatts are research-grade free. SurgePV offers a free trial with no credit card and full features. Past 10 deals/month, the all-in cost of a free tool typically exceeds a flat $1,299/user/yr SurgePV team-5 plan.
TL;DR
Best free entry. OpenSolar core for residential. SAM (NREL) for research. SurgePV trial for full-feature evaluation. When to upgrade. Past 10 deals/month or any C&I project. Book a free SurgePV demo.
The 4 genuinely free solar design tools in 2026
1. OpenSolar (free core)
What it is. A commercial cloud platform with a free tier that includes basic design and proposal.
Best for. Solo installers doing under 5 sub-10 kW residential deals a month.
The catch. Bankable shading, e-signature, finance integrations, and hardware connectors all sit on the paid tier or in per-deal add-ons. Above 10 deals/month, the all-in cost climbs fast.
2. SAM (System Advisor Model, NREL)
What it is. Free, open-source, research-grade simulation built by NREL.
Best for. Researchers, students, utility-scale early feasibility, policy analysts.
The catch. Desktop install, steep learning curve, no proposals, no design layout. Built for engineers writing papers, not installers closing deals.
3. PVWatts (NREL)
What it is. Free online calculator for residential yield estimation.
Best for. Quick yield estimates, customer education, sanity-checks.
The catch. Calculator, not a design tool. No layout, no SLD, no proposal.
4. SurgePV (free trial)
What it is. A free trial of the full SurgePV solar design platform, no credit card. Includes AI 3D solar roof modeling, 8,760-hour shadow analysis, and a bankable yield report tool.
Best for. Anyone serious about evaluating a full-stack tool before committing. Try the free SurgePV demo or jump to SurgePV pricing.
The catch. It is a trial, not a permanent free tier. After the trial, the team-5 plan is $1,299/user/yr.
What the "free" actually costs you
The hidden costs of free solar design software fall into four buckets:
Per-deal fees
OpenSolar charges per-deal fees for finance integrations and some hardware connectors. SAM and PVWatts do not, because they are not sales tools.
Subscription tiers above "free"
OpenSolar's actually-useful features live on paid tiers ($30-$100/user/mo).
Bolt-on tools
Free design tools usually do not include the proposal or e-signature. You buy those separately, the total cost climbs.
Time
The biggest hidden cost. SAM takes weeks to learn. OpenSolar's UX is good but the C&I workflow forces manual workarounds. Time-to-first-proposal is hours longer on free tools than on paid ones.
Watch out. "Free" sounds attractive at deal #1. By deal #50, the all-in cost of OpenSolar with add-ons typically exceeds SurgePV's flat team-5 plan.
When to upgrade from free to paid
Three triggers, any one means stop using free:
- You take a C&I bid above 50 kW. Bankable shading + multi-array workflow stops being optional.
- Deal volume crosses 10/month. The math of per-deal fees vs flat subscription flips.
- You bring on a second designer. Team collaboration features become worth real money.
SurgePV trial: what you get for free
The SurgePV free trial includes:
- AI 3D roof modeling from satellite
- 8,760-hour module-level shading
- Bankable P50/P75/P90 yield reports
- Auto SLD + BOQ
- Branded PDF + interactive web proposals
- Clara AI design assistant
- Full module/inverter database
You can design real projects and ship real proposals during the trial. No credit card required.
See the math live
Free trial of SurgePV ships the full $1,299/user/yr feature stack. Use it on real projects, then decide.
According to IEA's Renewables 2024, the average installer team size and deal volume have grown faster than free-tool feature sets. The math of free-vs-paid favours upgrading earlier than most installers expect.
Where QuickEstimate fits
For Indian EPCs, QuickEstimate offers a free plan: 10 proposals/month, no card. See best solar CRM software in India and the proposal, SLD, and BOQ glossary entries.
Try the full SurgePV stack for free.
No credit card. Design real projects. Ship real proposals. Decide at the end of the trial.
20 minutes · Bring a real project · No credit card · Or see pricing
Frequently asked questions
What is the best free solar design software in 2026?
OpenSolar's free core for small residential. SAM (NREL) for research. SurgePV's free trial for full-feature evaluation.
Is OpenSolar really free?
The core platform is free. E-signature, premium support, finance integrations, and some hardware connectors are paid or per-deal.
Is PVWatts a design tool?
No. PVWatts is a quick yield calculator from NREL, not a layout or proposal tool.
Does SurgePV have a free tier?
SurgePV offers a free trial with full features. The paid plan starts at $1,299/user/yr for teams of five.
When should I upgrade from a free tool?
Three triggers: any C&I bid above 50 kW, deal volume above 10/month, or onboarding a second designer.
Are free solar design tools bankable?
SAM produces bankable outputs but with research-grade UX. OpenSolar's free tier shading is simplified, not bankable. SurgePV's trial includes full bankable simulation.
Want to put this into practice?
QuickEstimate gives you everything in this article, proposal automation, lead capture, WhatsApp follow-up, built for Indian solar EPCs.
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