Peak Sun Hours in São Luís, Maranhão, Brazil
- Solar zone
- Zone 4 (excellent)
- Best month
- September (6.0)
- Worst month
- April (4.6)
- Climate
- Equatorial · 27.2°C
Monthly solar breakdown
| Month | GHI | Clear-sky | DNI | DHI | Temp °C | Humid % |
|---|---|---|---|---|---|---|
| Jan | 4.91 | 6.96 | 2.83 | 2.38 | 27.1 | 82 |
| Feb | 4.75 | 7.13 | 2.49 | 2.35 | 26.6 | 87 |
| Mar | 4.68 | 7.14 | 2.39 | 2.30 | 26.4 | 89 |
| Apr | 4.62 | 6.85 | 2.47 | 2.27 | 26.4 | 91 |
| May | 4.75 | 6.40 | 3.30 | 2.08 | 26.7 | 90 |
| Jun | 4.98 | 6.16 | 4.23 | 1.89 | 26.6 | 87 |
| Jul | 5.24 | 6.28 | 4.66 | 1.85 | 26.6 | 84 |
| Aug | 5.79 | 6.65 | 5.09 | 1.93 | 27.5 | 77 |
| Sep | 6.05 | 6.92 | 4.97 | 2.09 | 28.0 | 73 |
| Oct | 5.97 | 7.03 | 4.61 | 2.27 | 28.2 | 72 |
| Nov | 5.67 | 6.91 | 4.14 | 2.36 | 28.3 | 73 |
| Dec | 5.28 | 6.80 | 3.58 | 2.36 | 28.0 | 75 |
GHI, Clear-sky, DNI, DHI in kWh/m²/day. Data: NASA POWER climatology (long-term monthly averages).
Off-grid calculator
Add appliances
- Add an appliance to size a system.
Sizing
- Daily load
- 0.00 kWh
- Panel wattage
- 0 W
- Panel count (400W modules)
- 0
- Battery bank
- 0.0 kWh
Sizing against worst-month PSH of 4.62 kWh/m²/day, 0.77 system efficiency.
About solar in São Luís
São Luís, Brazil sits near the equator, where day length is stable year-round and the sun passes close to overhead. Its annual peak sun hours average 5.22 kWh/m²/day, a excellent solar resource by global standards.
The strongest month in São Luís is September (spring) at 6.05 kWh/m²/day, and the weakest is April (autumn) at 4.62 kWh/m²/day. When sizing a year-round off-grid system, it's standard practice to design against the April value rather than the annual average — otherwise the battery bank runs low during the darkest weeks.
São Luís's solar conditions are well within the range where off-grid PV is a straightforward engineering exercise with standard-sized arrays and lithium batteries.
FAQ
- What are the peak sun hours in São Luís?
- São Luís averages 5.22 peak sun hours per day annually, ranging from 4.62 in April to 6.05 in September.
- How many solar panels do I need in São Luís?
- Panel count depends on your daily load. At São Luís's annual average of 5.22 kWh/m²/day, a 5 kWh/day load needs roughly 4 × 400 W panels. Use the calculator above for your actual load.
- What size battery do I need in São Luís?
- Sizing against São Luís's worst month (April, 4.62 kWh/m²/day) with 2 days of autonomy at 80% depth of discharge, a 5 kWh/day load needs about a 12.5 kWh battery bank.
- How does São Luís's solar resource compare globally?
- São Luís sits in solar zone 4 out of 5 (where 5 is strongest) at 5.22 kWh/m²/day — excellent by global standards. For reference, top-tier desert sites average ~6.5 and high-latitude cities around 2.5 kWh/m²/day.
- Why doesn't solar output vary much by month in São Luís?
- Near the equator, day length is nearly constant year-round and the sun stays close to overhead. In São Luís, monthly PSH ranges just from 4.62 to 6.05 kWh/m²/day — variance is driven by wet-season cloud cover, not day length.
- What tilt angle works best for panels in São Luís?
- At latitude 3°, panels in São Luís work best at a low tilt (roughly 3°) or horizontal. Tracking mounts add little benefit this close to the equator.
- How does the wet season affect solar output in São Luís?
- Equatorial wet seasons reduce output through cloud cover, not day length. São Luís's worst month (April) still delivers 4.62 kWh/m²/day — design against this value for reliable year-round off-grid use.