I had four of the basic solar panels connected to the basic batbox, which was powering a macerator.
I turned away, placed an ender chest down and boom!
The redstone engine wouldn't have caused that big of an explosion, it looked bigger than a creepers, and the macerator wasn't even running, so it must have been the bat box that exploded. It was also full, but why? The only input to it was a few basic solar panels.