Seeking advice on PV wiring.

[Dan Sr]

I am not an electrician and a novice with solar systems as you can tell by my post. I have a second house secluded in upstate NY with an off-grid solar system. The main solar panels are located on the roof all connected together and the previous owner as an afterthought installed a smaller panel independent from the main panels which are all connected to the solar system. The main panels have red and black wires and are plugged in together. The single panel has a white and black wire that connects directly to the panel without a plug. My sons temporarily removed the panels from the roof for a roof replacement. They labeled all the wiring to the main solar panels but neglected to label the white and black wire to the single panel. The single panel has the positive and negative connections marked. I’m aware that in AC wiring the black wire is always hot and the white is neutral. I’m also aware that DC wiring uses black as negative and read that most solar panel wiring uses red as positive. I’m confused as to why the previous owner did not use red and black wires for the single panel. I searched on YouTube and there were discrepancies, most noted that the black is always negative, and some noted that it can be used as positive. In reinstalling the panels, my sons connected the black to the negative and white to the positive on the single panel, but I have concerns if the connections are correct. I also read that if we check the connections at the solar panel with a DC voltmeter and have a minus reading the polarity is reversed. My voltmeter has 5 DCV settings and am not sure which setting to use. I apologize for the long posting and would appreciate any and all help. Thank you, Dan Sr.

[organic farmer]

Using a voltmeter, always start at its highest setting. take a reading and then work your way down to whatever scale gives you a mid-range reading.

[Dan Sr]

Thank you for your advice on the voltmeter.

[organic farmer]

Regarding the colors of wires. It is okay to assume that a previous person used the common rule of thumb but always verify for yourself.

Just because a wire is red, or black, or white, or green, does not guaranteed anything.

My father was a construction electrician, he worked for the IBEW for 40 years. He wired thousands of homes and shopping centers and even did a lot of wiring at a nuclear power plant. yet he was also color blind. He routinely asked a fellow electrician to verify what color wire he was holding. One of his favorite stories to tell was one time while wiring a building at the nuclear power plant, he asked a co-worker what color a wire was, and the coworker responded that he had no idea he was also color blind.

Use a volt meter to verify what each wire does.

[Dan Sr]

Thanks again along with the funny but scary story lol