I am puzzled why the roof was not designed to have a steep pitch so that it would more readily shed snow. With solar power running things, am surprised that some safer system for snow removal was not put in place other than a wooden (slippery) walkway far off the ground. If I was 20 years old I would not want to go up there to clear snow.
The least he could do, to save himself some labour, is putting tarps on the solar panels at night.