In climates where you will have a bed of snow during the winter months, your optimum tilt angle for a fixed solar panel is something like 30° off of vertical or steeper. I find that on mine the snow falls off since it is a south facing, steep, dark surface.
You engineer to make sure you have enough energy captured each month to meet that months needs. That might lead you to a tilting mount, or just a fixed angle and having surplus energy most months.
In my case, panels were much more expensive when I designed my system, I initially roof mounted them, but when replacing the roof under them I moved them to a pole and went with a tilting mount and manually move the panels twice a year. My load is much higher in the summer, but I still need some power in the winter. And northern winters can be cloudy a lot and have limited sun even on a clear day. At my location there is about a factor of 5 difference in solar energy per square meter per month. So you design for each month and then pick a solution that is best. In my case the summer load is so high that even though I get 5 times the energy, it is still the driving force on sizing the system.