Nkiernan I would love to have a chat with you about these packs, can you pm me? I have a pack in bits and reconfigured to run with my solar. Its fantastic. I have a few issues you might know the answer to.

Yes you need a special flux for aluminium.
You put a blog on the aluminium first. The tin the wire, tin the iron and then solder to the pre-fluxed pad. Its like a miracle compared to not using it.

Just google it, there are lots of manufacturers. Must be for aluminium, not just any old soldering flux.