Tilt your solar panels to 15° facing north in Riacho de Santana. That is the most efficient fixed angle for this exact spot, measured from satellite records of its sunshine and cloud rather than worked out from latitude. The full breakdown, including seasonal and monthly adjustments, is below.
Today, the most efficient tilt for photovoltaic panels in Riacho de Santana is 10.2°, facing north. At solar noon the sun sits 79.8° above the horizon. Setting your panels to this angle keeps them as close to perpendicular to the sun as possible, which is where they generate the most electricity.
Your photovoltaic panels need to be angled facing north. Riacho de Santana is in the southern hemisphere, so panels catch the most sun facing north.
If you're mounting the photovoltaic panels at a stationary angle, such as on your roof, the most efficient angle is 15°.
If you're planning to change the angle of your photovoltaic panels twice per year, the most efficient angle is 8.3° facing south in summer months and 31.1° facing north in winter months.
When changing the angle of your photovoltaic panels each season, the most efficient angle is 11.8° facing south in summer months and 36.1° facing north in winter months, and 11° facing north in autumn and spring months.
If you adjust your photovoltaic panels every month, the table below gives the most efficient angle for Riacho de Santana throughout the year. The shallowest angle is 1.8° in October, and the steepest is 37.0° in June.
| Month | Optimal tilt | Facing | Sun angle at noon |
|---|---|---|---|
| January | 6.5° | South | 83.5° |
| February | 2.4° | North | 87.6° |
| March | 13.2° | North | 76.8° |
| April | 25.2° | North | 64.8° |
| May | 33.7° | North | 56.3° |
| June | 37.0° | North | 53.0° |
| July | 34.0° | North | 56.0° |
| August | 25.4° | North | 64.6° |
| September | 13.4° | North | 76.6° |
| October | 1.8° | North | 88.2° |
| November | 6.8° | South | 83.2° |
| December | 9.8° | South | 80.2° |
The sun angle at noon is how high the sun sits above the horizon at midday. Facing your panels north at the tilt shown for each month keeps them as close to perpendicular to the sun as possible, which is where they generate the most electricity.
In Riacho de Santana, November is the worst month and generates 81% of what September does: about 123 kWh per kW of panels against 151. Size an array or battery for November, not for September, or it will come up short.
Averaged across the year, panels at the best fixed angle see 6.1 peak sun hours a day. That is the figure to use when sizing an off-grid system, but size it for November rather than for the average, or it will run flat when you need it most.
For Riacho de Santana it is measured, not calculated. PVGIS, the European Commission's solar radiation model, works through years of satellite records of the sunshine and cloud at this exact coordinate and finds the fixed angle that collects the most light over a whole year. That is 15°.
Latitude sets the starting point, because it sets how high the sun climbs. It cannot see the rest: how cloudy the winters are, how much of the light arrives diffuse rather than direct, and whether hills block the low sun. A rule based on latitude alone gives 14.9° here. Even the best such rule, fitted to every city PVGIS has measured, misses a typical place by two and a half degrees, and a valley or a cloudy coast by far more. The seasonal, monthly and daily angles above do still come from latitude, because those follow the sun's height through the year, which latitude does determine. How the figures are worked out.
The angle is settled. Here is what is worth checking on the panels themselves:
Fixed angle and generation measured with PVGIS at this location's own coordinates, © European Union, 2001-2026, CC BY 4.0.