Free solar PV design software compared
Solar design software ranges from free one-line yield estimates to paid tools for bankable reports. This table shows which tool fits which step of a project.
At a glance
The table is wide: scroll sideways for shading, yield model and best use.
| Tool | Price | Runs on | Layout | Shading | Yield model | Best for |
|---|---|---|---|---|---|---|
| PVdesignEYA | Free | Web browser | Automatic: draw the site on a satellite map | Real 3D terrain, trees and buildings | PVGIS weather data, loss diagram | Fast pre-feasibility: layout, shading and yield |
| PVsyst | Paid license | Windows desktop | Manual (build a 3D scene) | Near 3D shading, horizon | Detailed hourly simulation | Final bankable and permitting reports |
| PVWatts (NREL) | Free | Web browser | None | Enter losses as % | Simple model | Quick yearly estimate from an address |
| SAM (NREL) | Free | Windows, Mac, Linux desktop | None (dimensions only) | 3D shade calculator included | Detailed performance + financial model | Financial and revenue analysis |
| PVGIS (EU JRC) | Free | Web browser | None | Terrain horizon only | Satellite irradiation data | Irradiation and yield for a location |
| HelioScope | Paid subscription | Web browser | Yes | Yes | Detailed simulation | Commercial and industrial design |
| Aurora Solar | Paid subscription | Web browser | Yes (mainly rooftops) | Yes | Detailed simulation | Residential sales and design |
| OpenSolar | Free (installer sign-up) | Web browser | Yes (mainly rooftops) | Yes | Simulation + proposals | Installer quotes and proposals |
Based on each tool's public information as of November 2026. Prices and features change, so check the official site before you rely on it. PVsyst is a trademark of PVsyst SA. PVdesignEYA is our own tool, the one that publishes this page.
Which one should you use?
- Just a yearly kWh estimate for an address: PVWatts or PVGIS. Both are free.
- How many kW fit on your land or roof, and what shading costs you: you need a tool that does layout and shading together. PVdesignEYA does auto layout, 3D terrain shading and yield for free once you draw the site on a satellite map.
- Payback, financing and revenue: SAM is the most detailed free option. For a quick number, try the solar payback calculator.
- Final reports for banks or permits: PVsyst is still the industry standard. Many teams do early checks in a free tool and move to PVsyst once the design is fixed.
Using it together with PVsyst
A layout made in PVdesignEYA can be exported as a PVsyst near-shading 3D scene (.pvc2), with terrain, tables and trees, so you do not have to redraw it. This export uses free monthly points after you log in.
Try it free
No install and no sign-up: draw your site in the browser and get auto layout, 3D shading, yearly yield and an A4 report.
Design for free →FAQ
Is there a free alternative to PVsyst?
It depends on the job. PVWatts and PVGIS give free yield estimates, SAM does free financial modelling, and PVdesignEYA does free layout and 3D shading. Bankable reports are usually still made in PVsyst.
Do I need PVsyst?
For early checks and internal decisions free tools are often enough. You need PVsyst mainly when a bank or investor asks for a PVsyst report.
Can I move a PVdesignEYA layout into PVsyst?
Yes. Export it as a PVsyst near-shading 3D scene (.pvc2) and the terrain, tables and trees open as they are. It uses free monthly points after login.