The covered porch will make it darker in the home during the afternoon. - And so will the shade trees. Most of the time I take common sense for granted, but the feedback from some realtors is just amazing.
I have two houses listed that have covered porches on the west side of the homes. I get feedback constantly that the homes seem dark in the afternoon compared to some of the other homes they have looked at. When I ask the realtor of the other homes had covered porches, they ask what difference does that make. It keeps the sun off the house, making it darker.
Shade trees do the same thing, and I get the same comments about the dark home. People use your head and think about why it's dark when the blinds are open. That doesn't mean that anything is wrong with the house.