INPE · ANEEL · Lei 14.300
Is rooftop solar worth it at your home?
Free, transparent simulation with official INPE data and Lei 14.300 (Brazil's distributed-generation law, the so-called “sun tax”) already in the math. No signup, no phone number, no sales pressure.
Simulate my savings (in Portuguese) →Takes less than 1 minute
Example: São Paulo/SP
Home with 400 kWh/month on CPFL Paulista — irradiance 4,7 kWh/m²·day (INPE).
System
3,4 kWp
Investment
R$ 9.747
Savings/month
R$ 283
Payback
2 anos e 10 meses
1
Your electricity bill
Average amount and consumption — straight from a recent bill.
2
Where you live
We match it to INPE's solar atlas: 5.569 municipalities covered.
3
Instant result
System size, investment, payback and 25-year savings — with Lei 14.300 calculated year by year.
Why trust this simulation?
- ☀️ Real irradiance for your municipality — Brazilian Solar Energy Atlas (INPE/LABREN), not a national average.
- ⚖️ Lei 14.300 modeled year by year — Fio B (the grid-use charge on credited energy) rises from 60% (2026) to 90% (2028) and changes your payback. Most calculators ignore this.
- 🔍 Open methodology — every assumption has a cited source and you see the full 25-year table.
- 🤝 No conflict of interest — we don't sell panels or hide the result behind a form.