You can do it, it just takes a different technique. I've soldered a lot of wire to AL battery cases and the occasional sheet.
You need to use an iron or gun with enough wattage to heat the AL, which may be difficult due to the large mass/area that needs heating. AL conducts heat really well, meaning you're trying to solder to basically a big heat sink. Also, solder will stick to AL but not to aluminum oxide, which forms almost instantly when it's exposed to air. Clean it, scuff it, doesn't matter, by the time you get the solder to it, it's oxide coated.
The solution is to scuff the surface while it's covered from exposure to air. I have read of people using oil to coat the area to be soldered. haven't tried that, although it sounds reasonable. I have used an iron with a sharp or rough tip to melt a puddle of solder, then scrape away the area under the solder puddle. When you rub away the oxide the solder will stick. Once that happens you can get a good joint with the wire.
That said, when I need to attach a wire to a piece of sheet metal it's usually time for a ring lug, screw and a coupe of washers.