Okay, this is a hard one as I don't remember very much, and can't figure out what to Google, but here goes. This is one of those 1990 straight to VHS type movies (probably) with decent production value.
From what I remember, a family moves to a dangerous, hot environment where you would be burned outside in the day in a short period of time. The father is possibly a scientist, and is working with plants (maybe reptiles) in the family's basement. The boy becomes affected by his father's work and is an outcast at school. One scene involved him being left outside to burn tied to a post, where he survived due to his affliction. His dad may form into a planet like creature in the end, or the planet is eating his family..possibly.
This may be all in my head, but I am pretty sure it was a movie.