The roof doesn't need to "withstand" snow. It just needs to be sloped enough for it to fall down.

Source: My dad has his hobby car in a glorified tent during winter, works just fine, the roof is in a 45 degree-ish slant so any snow just falls off.

45° wouldn't work well with any overhangs which are not facing south - not when the goals is to put solar panels on them.

And I, every winter, see snow clinging to 45° roofs quite often. Slightly wet snow (also the heaviest snow) can even stick to vertical surfaces.

45° would also make an overhang more susceptible to wind forces, acting like a sail.