Broken Solar panel, need electrical expert advice

DickyDck · September 2019

Well I was wondering when it would happen and it finally did. Was mowing the lawn and flung a rock straight through a panel. SO my question is, what is the drawback/down side of having a string of 3 with a dead panel. on one inverter I have 4 strings of 3 panels (forgive me if I get the terminology wrong I forget if String is the proper term) , now I have 7 strings of 3 and 1 string of 2. what does something like that do to the system? In my naive understanding of electricity, my math works like this...

Original unbroken setup was 12 panels x 300 watts = 3600 watts
Now with broken is 11 panels x 300 watts - 3300 watts

I'm sure this is over simplified, and it doesn't work this way, hence I'm here asking for experts! Please let me know asap if this is in some way a fire hazard and I should unplug that one panel, or unplug that string of 3.

Estragon · September 2019

IMHO, you're probably best to take the string with the damaged panel out of service.

With it in the mix, you have 3 strings at ~100v, and one much lower, so the controller may have trouble tracking MPP.

BB. · September 2019

Yes, disconnect the bad string (and broken panel). It is a fire hazard.

-Bill

DickyDck · September 2019

Done, what’s weird now is, I’m watching both charge controllers and one would think, one controller has 12 panels, the other now only has 9, and both are reading more or less equal power input. Is this by design, or are they both load balancing between the 21 panels in use?

Estragon · September 2019

Are they in bulk? If in absorb or float, they won't put out max current,,just enough to hold voltage and supply other loads.

DickyDck · September 2019

At the time they were in float, however since I am grid tied, I thought they would still kick out almost full power and the rest goes back into the grid? or does that happen in the inverter and the watts shown on the charge controllers not reflect that? I didn't see what the watts on the inverter were when I was looking at the 2 charge controllers.

DickyDck · October 2019

next question, I unplugged the cable from one end of the string and the other, should I also hit the breaker... if I can figure out which one it is anyway, in the combiner box?

Estragon · October 2019

I would have opened the string breaker first, but yeah I'd still open it. It should be the one with no voltage.

DickyDck · October 2019

and now that the sun is out, and it is in Bulk I can see a difference in the wattage, and voltage between the 2 charge controllers. weird though one has higher watts/lower volts and the other has lower watts/higher volts.

Estragon · October 2019

Just a guess, but the higher wattage means higher current, and more voltage drop (assuming same wire size and roughly equal length).

DickyDck · October 2019

Just as a testing FYI, I tried taking the 2 working ones and running those, and it just made the whole string wonky. so I think I had asked a question in another thread about that, having a string of 3p, 3p, 2p cripples the whole string. I have a replacement panel that is 320w opposed to the 310w the rest of mine are. I am pretty sure the new replacement panel will just be nerfed to 310 to match the other 2. Wiring it up later today weather permitting.

Solfyr · October 2019

Please make sure, that the Imp of the newer 320 Watt panel is within the Isc of the older
310 Watt panel .
Guessing , that they are 60cell panels both old and new .
96cell panels have similar measures , as 60cell panels have .

From reading the whole thread , I am assuming , that there are 2 Charge Controllers feeding
one Battery Bank , and one Grid Tied Inverter attached to the BB .

What are the make and models of each hardware involved , like SMA Sunny Island , to find out ,
if the Inverter ( Inverter Charger ? ) feeds into the grid , regardless , if loads are switched on .

DickyDck · October 2019

Thanks for the input! Everything as far as hardware is Schneider, xw6848 and mppt60150, panels are all hanwha, except the new ones are 320w, old ones are 310w same model series hanwha qcell

Solfyr · October 2019

What is the progress of the repairs ?

The Hardware looks ok to feed into the grid .

DickyDck · October 2019

Will be setting up tomorrow! I will let you all know, was going to do it last weekend but other household tasks took priority

DickyDck · February 2020

sorry I forgot to reply, so what I did was get 4 panels. One to replace the broken one, and 3 more as additional. I have the additional 3 added and everything appears to be working as expected. it is the off season for sunlight so I imagine the output will be higher come spring. Used to see averages around 5.0-5.8 on clear days. hoping to see mid 6.x come spring summer.

Broken Solar panel, need electrical expert advice

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