[jws]

At 45°N latitude, I keep mine nearly vertical year round. I used to adjust them 4 times a year for more optimal production. There are issues beyond angle of incidence. Being nearly vertical keeps the snow off in the winter. In the summer it reduces the cleaning required (it's a sea bird rookery, so that's kind of a lot). Beyond that, the telemetry needs are constant year round so if the panels can cover the needs in the winter, then summer is no problem.

My current strategy for small installations when you have an equator facing wall or fence is slap the panels on it and be done with it.