A concentrating collector is located at φ = 27◦ and is rotated about a single axis so as to always minimize the angle of incidence of beam radiation on it. On April 5, at solar times of 9 AM and noon, calculate the angle of incidence:

The angle of incidence of direct rays on an inclined receptor surface depends on the angle of inclination в of the surface to the horizontal, and also on the surface y. From a given position of the sun (zenith angle dz and solar azimuth y), the angle of incidence can be calculated from the horizon coordinates dz and ys:

( take below as assumption for better understanding)...

1) cosd = cos0z cos в + sin0z sin в cos (ys — y) (2.16)

or, when using equator coordinates 8 and o,

cos# = (cosв sinФ + cosФcos/sinP)sinS

+ (cosв cosФ-sinФcos/sin/3)cosScosa (2.17)

– sin/sin в cos S sin®

Simplifications of the formula result e. g. from horizontal surfaces with в = 0° (Equation (2.12) of the zenith angle) or vertical and south-oriented facade surfaces (в = 90°, / = 180°):

cos в = – cos Ф sinS + sin Ф cosScosa (2.18)

so as per thisys says The direction of the sunlight depends on the position of the sun relative to the photovoltaic modules and on the degree of disturbance that the solar radiation suffers( depends upon situation) while traveling through the atmosphere from space to the Earth’s surface.