Just like a typical battery you may be familiar with solar panels have positive and negative terminals.
How to tell which wire is positive solar panel.
Another way to find the polarity of the solar panel is to check with a volt meter.
Red and black are acceptable colors to use.
Enter the distance in feet from your solar panels to your battery bank charge controller.
Grounding the positive is also nec compliant and would thus have a white wire carrying positive.
A simple voltage reading will show you the polarity of a solar panel even when inside.
Set the volt meter to read dc volts.
To measure across the solar panel terminals or wires put the red positive meter lead on one side and the black negative on the other.
The positive wires are connected to a positive connector within a combiner box and the negative wires are connected to the negative connector.
If this is an ungrounded system also compliant in some circumstances then neither wire should be white.
On bare wires a red identifies the positive lead and black the negative lead.
Feel the other wire which is smooth.
As most solar panels are 12 volts the solar panel test methods are basically the same.
On a quick connect plug b coming from the solar panel the covered female part is the positive lead and the exposed male prong is the negative.
When stringing in series the wire from the positive terminal of one solar panel is connected to the negative terminal of the next panel and so on.
This is your positive wire.
When solar panels are wired in parallel the positive terminal from one panel is connected to the positive terminal of another panel and the negative terminals of the two panels are connected together.
How to test a 12 volt solar panel vs other voltages.
If you have a wire where both sides are the same color which is typically copper the strand that has a grooved texture is the negative wire.
Enter the total amps that your solar panels will produce all together.
Run your fingers along the wire to determine which side has the ribbing.
Enter solar panel output voltage.