Size your off-grid solar system
A free sizing tool for self-builders: from requirements to a final report, with calculations based on real PVGIS production data — not a quote, a solid starting point for your project.
How it works
Twelve steps in four stages, always editable as you go
The path is twelve steps, grouped into four stages. You can go back to any step and recalculate everything.
Requirements & arrays
Requirements, exposure, panels, strings: system type, orientation, tilt and shading for every surface you have available.
Battery, inverter, cables
Load profile, battery, inverter, cable sizing: full technical sizing — battery capacity, inverter rating, conductor cross-section.
Real production data
Production and balance: monthly/annual production estimates from PVGIS (European Commission) for your exact site.
Hardware & report
A downloadable summary with 3D renders of your arrays, ready to bring on site.
One guided path, from start to finish
Always start from the guided version — a system with one roof or area, estimated annual consumption, step-by-step intro tour. No account required. The more advanced features stay one click away for the whole path, never a forced choice up front.
From the start
Whenever you need it — "Unlock advanced"
Unlocks with a click right inside the guided path — free, no account needed, never a decision you have to make in advance.
State of charge · 24h simulated
Feedback
Help us improve
Have you tried the tool? Let us know what worked and what didn't — feedback is only used to decide what to improve, never shown publicly.
Support
Questions or feedback? Write to latuaisola.support@gmail.com.
Free
Simplified and Complete are both free, always — no payment required, no account needed to use them. Anyone who purchased previously keeps their access unchanged.
Stays private — only we read it, never shown to other users.
Opens your email app with the message ready to go — no account needed.
Support the project
The tool stays free thanks to people who support it. If it was useful to you, a free donation helps keep it updated.
Pre-sizing tool. An indicative pre-sizing tool, not a certified electrical design. Always have your installation verified by a qualified electrician in line with REBT (Reglamento Electrotécnico de Baja Tensión) (generally harmonised with the IEC/CENELEC 60364 standard) before connecting anything.