[junkomi]

Oh sorry. I mistook 日影(hikage) for 日陰(hikage).

All of you are correct on the meaning of 日影.
But in fact, Japanese associate "hikage" with 日陰(shade) first of all as well as I did.

And the cases that 日影 is used are limited　compared with 日陰.
example
夕暮れで日影がのびる。
障子（しょうじ）に日影がさす。

(name)さんは僕の光です or (name)さんは僕にとって太陽のような人です are better after all.