green trees and light

[demonfrog]

is there any real need to have a light set up for green tree frogs if sunlight is coming through the window?

[DonLisk]

Tree frogs are nocturnal and using direct sunlight, such as placing right next to a window, is not recommended.
Ambient sunlight would be fine for creating a day and night cycle and you frogs actually need no special lighting.

Just ensure your providing supplements such as calcium to their diet.