The idea is simple. To protect the expensive solar panels against the elements and possibly vandalism. Why not no add an outer transparent construction for them. With this you could have both a sloping outer surface and at the same time keep the solar panels horizontal inside. The slope will make it easier for snow and water to flow off and not to block the sunshine. The disadvantage which will vary is the performance loss because of an additional absorbing layer. The transparency is probably not a 100%. Overall I think this might be a good idea to keep the solar panels in a transparent container since it will give them a longer life expectancy.
Further if the outer cage or container is strong enough. You could walk on the solar panels which might be useful.