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Testing Polarity of Solar Panels

Craig Asks:

Hi There. I have installed a solar panel on my camper van. All the wires are now boxed in and i am unsure which wire is positive and which is negative. Is there an easy way of testing this.Thanks.

Solar Ron Says:

Hi Craig,


I will try to help you with this issue. To test the polarity of the solar panel cables is quite easy. To do this you will need a multi-meter. 

First thing to do is to set the multi meter to an appropriate setting, i would use DC Voltage, Range 50 V DC+. (the solar panel can have an open circuit voltage of 40 volts or so, not setting the correct range may damage the meter. Just make sure its set above 50 Volts and you will be fine)

Next, carefully touch the probes from the multi meter to each of the solar panel wires, if you have a crocodile clip attachment for your meter it will be easier. Be careful not to touch both of the solar panel wires with your bare hands, you might get a nasty shock. Hence using crocodile clips may be safer. 

Now look at the reading on the meter, it will either be a positive reading or have a minus reading. If the reading is positive this means the positive meter probe is connected to the positive solar panel wire. If the reading is minus then the positive meter probe is connected to the negative solar panel wire. 

Once you have identified which one is positive and which is negative it is good practice to wrap some red insulation tape around the positive wire, normally a few inches from the end. 

I hope this is of good help to you.

Solar Ron - Solar Energy Advice & Solutions.  

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