Direct Normal Irradiance
(DNI) is the direct solar irradiance incident on a surface that is perpendicular to the irradiance plane. DNI irradiance is about direct line between the sun with its current position and the irradiance. The DNI value can be optimized by tracking the irradiance surface. This technique is used in photovoltaic systems by tracking the solar modules to the angle of irradiation of the sun, so that they are always perpendicular to the angle of irradiation of the sunlight.