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If you desire you can sue aluminum, the differences are cost, corrosion chances increase, especially in an outdoor installation,
You would need 2 ga aluminum to do it in copper. Now, think about related costs, larger conduit may be required, corrosion prevention goop. Some receptacles, etc are not rated for aluminum, be sure what you buy is if you choose to go alum.
For me, the material is but a part of the cost of the job. Labor, peace of mind, etc ned to be figured in as well.
Yes, copper is more expensive up front, but may be cheaper in the long run.
Your installation, your choice.
Good Luck either way