Lighting scene with 2D people/plants

tparks

I recently did an outdoor scene with several 2d people and plants and due to the sun angle (doesn't seem to matter which) they all come out somewhat dim.

The only time I can get them illuminate properly is if they are laying flat.

Has anyone ever dealt with this? Not sure what to do. I like to render them in the scene since it saves a lot of time placing them manually in photoshop.