Hi Marco
I use this site for best angle of panels, and different outputs from angles http://www.solarelectricityhandbook.com/solar-irradiance.html.
In northern hemisphere the panels should face south, but near the equator the sun is almost straight over head, so you want a low angle, like 10 degrees. However, if you have a greater angle, you will generate more power in the winter, so it depends whether you want best full year production, or more power in summer, or winter, if that makes sense.
Cheers
Marty