Hi, Andre Thank you for your reply. I have two more questions. In your reply, the shading factor is the ratio of shaded area. Does the shading factor =1 mean that the point is fully shaded ? (But in the tutorial, the factor=1 is no shadings.) In the tutorial, the shading factor table is for the positions on the sky hemisphere "seen" by PV plane (page 53) . It's like the "Height" depends on the tilt of PV plane. Does the "Height" mean the degree depndindg on the tilt of a PV plene or simply sun height? Sincerely, Kumiko