|Last update: May 2019|
Conventions on SoDa: plane modes and azimuth conventions
Firstly, the azimuth convention is:
So orientation checking is :
- A tilted plane is north oriented if azimuth < 90° or azimuth > 270°
- A tilted plane is south oriented if azimuth > 90° and azimuth < 270°
NB: A plane which is not facing the sun might either be a human error, or may also be due to infrastructure or environmental needs (e.g. part of the rooftop north oriented).
Note on the relationship between RTI (or RNI) and albedo:
The irradiation collected by a tilted surface is composed of a part of direct irradiation (as soon as the sun is visible by the panel), a part of diffuse irradiation coming for the portion of the sky vault visible by the panel, and a part of irradiation reflected by the ground. Indeed, when the plane is tilted, it "sees" a portion of the ground. Consequently the plane receives more solar radiation if the ground is highly reflected sun rays, i.e. for high albedo. The albedo caracterizes the reflective capacity of the ground. The default value on SoDa is 0.2. If the ground is not very reflective, like for instance dark ground, just set 0.1. Other examples of albedo values for oceans and seas is 0.05, 0.5 for sands, and 0.8 for snow.
Anyway, the reflected part is small compared to the other components, so the ground albedo is a second order input parameter.