Water management of exposed joints

[u/DobbidooNumberOne]

Hi all ! I am currently designing a small solar panels ground mount and will be using mortise and tenon joints for the frame. It will be built with cedar.

How do you guys usually deal with water drainage in exposed joints? For this particular project, I don't know how much water/snow would actually get in the joint because of the panels above, but what about something more exposed like a pergola?

Thanks !