We made the racks so that they could be on a slant or flat. Nothing complicated, just a simple bolt on one end that like be removed and placed in a different hole on the rack.
So the panels are now flat. The only problem is that rain tends to pool on them. But surprisingly it doesn't seem to be much of a problem. They generate plenty of electricity.
I'm really happy with our ground mounted panels. They are much easier to clean. Because of our ohia trees, the panels blacken over with whatever it is that comes off the trees. Cleaning that black stuff off regularly has been keeping our power generating ability high. By the way, these are unisolar panels. I don't know if that makes a difference with the pooling water issue.