PVWatts, PVGIS and SAM are public estimation and modeling tools, and OpenSolar’s core app is free for design and sales. Paid tools add features their vendors list by plan, such as LIDAR-assisted modeling and shade reports: Aurora from USD 135 per user per month billed annually, HelioScope from USD 1,620 a year, SurgePV from USD 1,299 per user per year.
SurgePV publishes this guide and sells one of the tools listed. The tables report what each vendor’s own pages state in October 2026. They do not score accuracy or rank the tools.
Free solar design software: what you get
Four free options cover different jobs, so read the last column before you pick one.
| Tool | Cost on the source page | What it does | Limits the source page states or leaves out |
|---|---|---|---|
| PVWatts | Published by the National Laboratory of the Rockies (NLR); no price listed | Estimates PV energy production from system size, module type, array type, losses, tilt and azimuth | NLR says results “include many inherent assumptions and uncertainties”. It gives no support, consulting or training. |
| PVGIS | The European Commission’s Joint Research Centre describes it as free and open access, with no registration | Grid-connected, tracking and off-grid PV performance, plus monthly, daily and hourly irradiation data | Inputs are installed kWp, losses, slope and azimuth, with an optional terrain-shadow setting. The tool page lists no layout or proposal output. |
| SAM | NLR calls it a “free desktop application” | Techno-economic analysis: PV from residential rooftop to utility scale, batteries, and financial models for residential, commercial, PPA and community solar projects | The page describes performance and financial modeling. It lists no roof layout or proposal output. |
| OpenSolar | The vendor says the core app stays free and that it earns revenue from hardware and finance partners | A design and sales app. The vendor’s menu lists Design, Auto Design, Single Line Diagrams and Proposal | From 16 April 2026 it charges for API access and for supported connectors such as Xero and QuickBooks. The page does not say which menu items are add-ons. |
The OpenSolar announcement is dated 16 February 2026. The core app has no charge as long as your workflow stays inside it. Connecting a CRM or accounting system is where the cost starts.
Paid solar design software: what the price buys
The prices below are the ones printed on each vendor’s own pricing page. Dollar figures are in US dollars.
| Tool and plan | Price on the vendor page | Listed in the plan | Limits listed |
|---|---|---|---|
| Aurora Basic | USD 135 per user per month billed annually (USD 1,620 a year), or USD 159 billed monthly | Tablet-friendly sales proposals, design mode, HD imagery, on-demand site models | 1 user, 50 projects a month |
| Aurora Premium | USD 220 per user per month billed annually (USD 2,640 a year), or USD 259 billed monthly | Everything in Basic, plus LIDAR-assisted modeling, bankable shade reports and battery modeling | 1 user, 50 projects a month |
| Aurora Enterprise | Custom | Adds AI-assisted site models, drone mapping, APIs and integrations, advanced permissions | Unlimited users |
| HelioScope Basic | USD 1,620 a year, or USD 159 billed monthly | Commercial solar-plus-storage design and simulation, rooftop, carport and ground mount | 1 user, designs up to 1.25 MW DC; 10 projects a month on monthly billing, 120 a year on annual |
| HelioScope Pro | USD 2,640 a year, or USD 259 billed monthly | Adds LIDAR-assisted modeling, AI-based obstruction detection, financial modeling and sales proposals, P90, P95 and P99 values | 1 user, designs up to 5 MW DC |
| PVsyst | The licensing page lists no price | Full capabilities in licensed mode | Needs an active license subscription; evaluation mode is 30 days |
| SurgePV | USD 1,899 per user per year for one seat, USD 1,499 per user for 3 seats, USD 1,299 per user for 5 seats | Roof modeling, layout, shading, energy yield, financial modeling, electrical workflow support, bill of materials, proposals | Guided demo; there is no self-serve trial |
Aurora’s annual plans carry a one-year commitment, and its monthly Basic and Premium plans have no minimum commitment. Premium support is an Aurora add-on. HelioScope lists basic support on Basic and Pro and premium support on Enterprise.
What a team of 1, 3 and 5 pays in licenses
List prices multiplied out, assuming one license per user and no volume discount, which these pricing pages do not list for these plans:
| Plan | 1 user | 3 users | 5 users |
|---|---|---|---|
| Aurora Basic or HelioScope Basic | USD 1,620 | USD 4,860 (3 x 1,620) | USD 8,100 (5 x 1,620) |
| Aurora Premium or HelioScope Pro | USD 2,640 | USD 7,920 (3 x 2,640) | USD 13,200 (5 x 2,640) |
| SurgePV | USD 1,899 | USD 4,497 (3 x 1,499) | USD 6,495 (5 x 1,299) |
The plans do not include the same features. Match the feature list first, then compare the price.
Free vs paid, feature by feature
| Feature | What the free tools list | What the paid plans list |
|---|---|---|
| Production estimate | PVWatts, PVGIS and SAM all estimate energy production | Aurora lists performance simulation, HelioScope lists production estimates and SurgePV lists energy-yield modeling. HelioScope states estimates within 1% of PVsyst, which is the vendor’s own claim |
| Roof and 3D modeling | OpenSolar lists Design. PVWatts, PVGIS and SAM take system size, tilt and azimuth rather than a roof model | Aurora lists 3D roof modeling and trees. HelioScope lists site modeling. SurgePV lists 3D roof modeling. LIDAR-assisted modeling is Aurora Premium and HelioScope Pro |
| Shading | PVGIS has an optional terrain-shadow setting. PVWatts has a system-losses input | Aurora Premium lists bankable shade reports. HelioScope lists shade reports. SurgePV lists shading analysis |
| Stringing and single-line diagrams | OpenSolar lists Single Line Diagrams | Aurora lists automated stringing and fire pathway placement. HelioScope lists single-line diagrams and CAD export. SurgePV lists electrical workflow support |
| Proposals | OpenSolar lists Proposal. SAM runs financial models but lists no customer proposal | Aurora Basic lists tablet-friendly sales proposals. HelioScope Pro lists sales proposals. SurgePV lists proposal generation |
| Support | PVWatts: NLR provides no support, consulting or training. OpenSolar’s site lists a support team and Help Center | Aurora lists a Help Center and on-demand training; premium support is an add-on. HelioScope support tiers are listed above |
When free is enough
- You need a production estimate for a lead or a feasibility check. PVWatts and PVGIS take a few inputs and return monthly and annual energy. Treat the result as an estimate, as NLR does.
- You model performance or finance for a project or study. SAM covers PV, storage and several ownership structures.
- You run design and sales in one app and keep your data inside it. OpenSolar’s core app has no license fee. Count the API and connector charges if you sync to a CRM or accounting system.
When to upgrade
- You need LIDAR-assisted modeling or shade reports. Aurora lists both on Premium. HelioScope lists LIDAR-assisted modeling on Pro.
- You design commercial projects above 1.25 MW DC. HelioScope Basic stops at 1.25 MW DC, Pro at 5 MW DC and Enterprise at 30 MW DC.
- You need PVsyst reports after the first 30 days. Evaluation mode uses generic components and puts a watermark on reports. After 30 days PVsyst drops to a demo mode.
- You want roof model, layout, shading, yield, financial model, bill of materials and proposal in one subscription. That is the scope SurgePV lists. Pricing is per user per year, and access starts with a guided demo.
- Your design work is occasional. Buying the work instead of a license is another route. See outsourced solar design services.
Permit, structural and lender requirements come from the responsible engineer, authority, utility or financier, not from the price of the tool.
Cost beyond the license
A license fee is one line. Add training, integration with your CRM or accounting system, the time to review each output, and the cost of moving projects out if you switch. Keep a time record on one real project in each tool before you decide, and run it with the same inputs. The software selection checklist lists the questions to ask.
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Frequently asked questions
What is the best free solar design software?
There is no single best. PVWatts and PVGIS estimate energy production, SAM models performance and finance, and OpenSolar’s core app is free for design and sales work inside the platform. Pick by the job: an estimate, a model or a full design and proposal.
Is OpenSolar really free?
The vendor says its core app stays free for end-to-end work inside the platform. From 16 April 2026 it charges for API access and for supported connectors to third-party tools such as Xero and QuickBooks. It says it earns revenue from hardware and finance partners.
Does PVsyst have a free version?
No. PVsyst runs in evaluation mode for 30 days with generic components and a watermark on reports, then switches to a demo mode. Full capability needs a paid license subscription.
How much does paid solar design software cost?
Aurora lists USD 135 per user per month billed annually for Basic and USD 220 for Premium. HelioScope lists USD 1,620 a year for Basic and USD 2,640 for Pro. SurgePV is USD 1,899 per user per year for one seat, USD 1,499 per user for three seats and USD 1,299 per user for five seats.
Is paid solar software automatically more accurate?
No. Results depend on the model, input quality, configuration, assumptions and review. Accuracy statements on vendor pages, such as HelioScope’s production estimates within 1% of PVsyst, are the vendor’s own claims.
Is a trial the same as free software?
No. A trial expires or restricts features. PVsyst’s licensing documentation describes an evaluation mode that lasts 30 days from installation, after which the software switches to a restricted demo mode. SurgePV does not offer a self-serve trial; access is through a guided demo.
Does commercial solar require paid software?
No rule ties a project type to a price. The responsible engineer, authority, utility or financier sets the deliverables, and you check whether your tool and review process can produce them. Size limits do apply by plan: HelioScope Basic designs up to 1.25 MW DC and Pro up to 5 MW DC.
Where this fits
This article is part of SurgePV's Solar Design hub, which works through the topic from first principles to the decisions a project team actually has to make.
