Originally Posted by Pongo
When I saw the original post, which expressed concern regarding solar hub gauge waiting, I contacted my dealer. (I've a 2017 International Serenity 27FB on order, with 160W solar on the roof and 160W of portable via the front solar connector for use in shade).
An Airstream electrical engineer responded back straight away. It's been a long time since I was a practicing electrical engineer, but I'm comfortable with his response. I've pasted a copy of his response below:
It is interesting that, despite his response, if you look at the table in the reference it clearly states that #10 wire in a power transmission application is rated for 15 amps.
His response is based on what is safe for the wire. Ampacity is a term from the National Electrical Code and is predominantly about AC power distribution in homes, businesses and industrial applications. It is essentially the electrical building code.
Lew has it right, as usual. Voltage drop in wires is all about resistance and current. The voltage drop in a wire at a particular wire size and current will be the same in a 12V
circuit as a 120V circuit, but proportionally it is 10x larger in the 12V
circuit. Depending on the charge controller, the impact can be even greater.
Series connection can help, but makes the shading problem worse. If I install solar, I will be replacing the existing wiring and running panels in parallel.