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Testing PV when MPP reads 0 V and 0WATT

cisumma

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Apr 2, 2021
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Set up the MPP and connected first string of PV: 2s1p , 48.7 v and 355 watts each panel.
Am I missing something? MPP shows no v and no watts.
Granted, it is my first time using MC4 connectors; and I did not get voltage readings off of each panel prior to install; my bad. The crimping is just okay ; but , the Male and female MC4 connectors are new to me.
Anyway, now I need to test the connections!
Now, the MC4 connectors warn: " do not discount during load "; and, I realize no one would recommend disconnecting during load ( plausible deniability) ; yet, if I did test at the panels is it known to be very hazardous or have people been known to disconnect these for testing?
Furthermore, did I miss something concerning plugging in panels for the first time?
Also, I had the panels out in the yard for a couple days befor I wired them. Does this hurt the panels?
Thanks
 
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Set up the MPP and connected first string of PV: 2s1p , 48.7 v and 355 watts each panel.
Am I missing something? MPP shows no v and no watts.
Granted, it is my first time using MC4 connectors; and I did not get voltage readings off of each panel prior to install; my bad. The crimping is just okay ; but , the Male and female MC4 connectors are new to me.
Anyway, now I need to test the connections!
Now, the MC4 connectors warn: " do not discount during load "; and, I realize no one would recommend disconnecting during load ( plausible deniability) ; yet, if I did test at the panels is it known to be very hazardous or have people been known to disconnect these for testing?
Furthermore, did I miss something concerning plugging in panels for the first time?
Thanks
 
no volts & no watts = no load. Feel free to disconnect as needed for testing of continuity.

No harm from solar panels sitting in the sun.
 
Thanks: yep, bad connection. At the panel it reads 80 v +- 3; but, the MPP is reading 40 +- . That's weird? 80 ft. Of 10awg & 30 amp fuse.
Real Quick, now the testing begins.
Are there any hazards if I begin plugging loads into a surge protecting power strip [ ex: radios, amp, piano , a couple led lights and maybe a computer; and, soon I will have that string and 2 more identical strings.
The temporary setup is to over panel a terrible southern facing location with absolutely no angle of inclination with tree cover and it is extremely cloudy here in STL. Personally, I am amazed that the 2s1p tested at 80 V at the panel.
Thoughts?
 
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It would be best to wait until dark to disconnect your panels unless you have a breaker between them and the controller. I do not have a breaker, but each string has an on/off heavy-duty 20-amp switch. Each series string only puts out a max of 9 amps, so the switches work just fine for switching my panels on and off during the daylight hours.

Regarding your MC4 connectors, it's easy to not have a good connection when you built connectors. or don't have a good seat with the connectors. - this happened to me.

After checking that you have panel voltage and current with a multimeter, then reconnect your panels to the controller. To be on the safe side, you could reconnect the panels to the controller at night to prevent any sparks or surge current into the controller. Note - I have never experienced any problems connecting my panels to my controller in daylight. Maybe I've just been lucky!
 
1st which MPP solar controller do you have?
2nd Does your controller have MC4 connectors on it or did you make a pig tail with an MC4 on one when and bare wire for a clamp screw on the other end?
3rd is the controller connected to a battery ?
 
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