Live PV upgrade from old to new combiner

Started by Riley, March 27, 2024, 12:02:43 PM

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Riley

Hi, I'm in the process of upgrading my roof top PV array from 12 panels to 18 panels (4 strings to 6 strings).

Note that these are roof top mounted and I'm not doing ground mounting for a number of reasons (plus the panels are now mounted). In order to do this, I am changing out the 4 string combiner to a 6 string combiner (MVP-6). Also note that most of the MC-4 connectors of the original 12 panel array are mounted under the array and are not accessible.

So I'm looking for safety advice/tips to do the moving of the live PV wiring from the old combiner to the new combiner. I'm well aware that the load (current flow) needs to be disconnected before opening any connections. Once that load is removed, I plan to move the strings one by one from the old combiner to the new combiner. Each string will have approximately 120vdc with a max current of 10 amps. The max current would be much less as I plan to do this combiner swap in the 3 or 4 hours of morning time when the panels are heavily shaded and should have a max current of about 1 -> 3 amps.

I am thinking I should wear electrical insulating gloves but thin enough that I can actually work effectively. I will be careful as possible but looking for other tips AND advice on good gloves. Given both neg and pos are floating with respect to ground should help things a bit but I know I shouldn't rely on this.

Thanks in advance.

Update: I think I will just cover my panels with a heavy tarp. I think I can easily cover 2 of the 3 panels per string. Getting to the 3rd panel is difficult reach.
Off-grid summer home: XW+6048 / 48V FLA battery bank (428 A/H (Rolls S-550 batteries)) / Conext MPPT 60 150 charge controller / SCP / Insight gateway / 12 - 260W solar panels / Kohler 12KW 12-RES propane genset

ClassicCrazy

#1
Is there no where in the string you can disconnect somewhere in the pv string ?  At the wire going from first or last pv to your combiner box ? If you disconnect it - pull one of the mc4 connectors apart when the combiner breaker is off , you shouldn't have any arcs . Do that for each string  Then you can work on the moving the wires from one combiner box to the other with no problem since the wires you are working on will be not be energized . After you are done , then you can simply snap the mc4 back together , and check everything with a meter . Once you are satisfied turn the combiners back on to energize .
Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

Riley

I can try to access the MC-4s but at last look, they were tied in pretty far back and hard to get at.
I think with a combination of disconnecting where I can, heavy tarp covering and early morning and gloves, I should be fine...
Off-grid summer home: XW+6048 / 48V FLA battery bank (428 A/H (Rolls S-550 batteries)) / Conext MPPT 60 150 charge controller / SCP / Insight gateway / 12 - 260W solar panels / Kohler 12KW 12-RES propane genset