Aluminium cables - Solar Panel Talk

Single conductor aluminum wire (AL-RW90) is generally installed in conduit & is available in AWG#6 & larger.

ACWU (armoured aluminum cable) is widely used in Canada at a fraction of the price of similar ampacity copper cable. For direct-bury use, it definately provides the best overall price performance for long underground runs. It is available in sizes AWG#6 & larger. Anit-shorts & correct terminating connectors must be used. Electricians only. It is widely available in the USA and is UL cert.

However, you must be a registered electrical contractor (or engineer) to even buy aluminum wire & cable. In which case you know the correct terminating lugs & joint compounds will be used. Careful attention to bend radius is more critical than with copper, and AL wire and cable can be easily injured during installation.

Voltage-drop calculations are part of any electrical design over a long feeder (like 900'), and Al has higher resistivity than Cu. Even so, in a direct price comparison, Al almost always wins over Cu. Cu gets used where the voltage-drop rule (5% max feeder + branch) simply rules out Al.

For the average home do-it-yourself solar guy, copper is what is available & what should be generally used.

If your project is of such a scale that economics dictate AL wire or cable, then using an electrical contractor will likely save you lots of $$$ in the long run... (true!) Your house won't burn down and your insurance will still be valid if it does.