日照, 陽光, and 日陰: exposure, sunlight, and shade
Compare 日照 affecting a room or surrounding area, 陽光 entering through curtains or lighting leaves, and 日陰 as a place to rest or grow. Read exposure conditions, light itself, and location.
Sunlight exposure for a room and its surroundings
日照（にっしょう） refers to sunlight exposure and can also name hours of sunlight. 「この部屋は南向きで日照に恵まれている。」（This south-facing room receives good sunlight.） この部屋 limits the good exposure to this room, with 南向きで identifying its direction. The sentence does not guarantee the same exposure for every south-facing room.
「高い建物が周辺の日照を遮っている。」（The tall building blocks sunlight from the surrounding area.） 周辺の日照 identifies the sunlight exposure that the tall building blocks. 遮っている describes that continuing state. Neither example supplies a numerical duration of sunlight.
Sunlight entering and leaves gleaming
陽光（ようこう） means sunlight or sunshine. 「朝の陽光がカーテンの隙間から差し込んだ。」（Morning sunlight streamed through a gap in the curtains.） カーテンの隙間から gives the path through a gap in the curtains, and 差し込んだ describes light streaming in as a past event.
「雨上がりの葉が陽光を受けて輝いている。」（Leaves are gleaming in the sunshine after the rain.） The leaves after the rain receive the light, and 輝いている describes their gleaming state. The focus is the light and what receives it, rather than an exposure condition.
Shade as a place to rest or grow
日陰（ひかげ） means shade or a shaded area. 「暑いので木の下の日陰で休んだ。」（It was hot, so I rested in the shade under a tree.） 木の下の日陰で identifies the place of resting, and 暑いので gives the reason.
「この植物は日陰でもよく育つ。」（This plant grows well even in shaded areas.） この植物 limits the claim to this plant, and 日陰でも says it grows even in shade. Distinguish exposure, light, and shaded place without turning one plant's example into a rule for all plants.
What are the focuses of 「この部屋は南向きで日照に恵まれている。」, 「朝の陽光がカーテンの隙間から差し込んだ。」, and 「この植物は日陰でもよく育つ。」?
Show the answer and why
日照 concerns the room's sunlight exposure; 陽光 names the light streaming in; 日陰 identifies the shaded place where this plant can grow. The last example does not generalize this plant's growth conditions to all plants.