Aluminium cables

[Solarex]

Hello solar buddies,

I want to ask you one question. Do you know any good reason why aluminium cables (DC cables) are not used in PV systems. Every MW project is with expensive copper cables. Thanks in advance.

[Sunking]

Because AL can be very dangerous with dis-similar metal connections, and takes training to terminate properly. In addition it takes much larger AL conductors to match copper in current carrying capacity.

[Solarex]

I see but when we have 5 MWp PV project and DC cables are 200-300-400 m from combiner (junction) box to Central inverter then AL cables with UV resistant seem to be more profitable.

[Mike90250]

I'm going to be pulling #2 aluminum cable for about 900' for my house & pump power. I'd rather use copper, but the price of #4 copper cable was astronomical. So I have to use the proper splices and NoOx coatings at the joints. Internal runs will be copper, just the long lengths will be aluminum .

[mountain]

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.