Alumium requires very few energy to melt, but this is for recycled aluminium. To get aluminiun from mines and extract from rocks (bauxite) and produce industrial aluminun, it's required electrolysis (which take a lot of energy to produce each kg of aluminium).
That's why it's important to recycle aluminium.
When electricity was relativelly new, the aluminium was more expensive than gold, due the processing required.
About solar panel carbon footprint :
http://www.onlynaturalenergy.com/201...oltaic-energy/
And a new solar panel with suposed lower carbon footprint :