Finally, the forces of the universe converge (i.e. a Saturday with excellent (i.e. non-freezing) weather when my co-installer (i.e. my son) is available) and a swap out of the LMUs can proceed.
My very kind neighbor has once again loaned me his scissor lift. My son and I evaluate the situation and decide that it would be best to remove all solar modules from the roof rather than try to perform the LMU swap on the roof. So that's what we did: started with the bottom row, loosened the restraining bolts, and lowered panels to the patio three to five at a time. This took about three hours and we broke for lunch.
In order to prevent theft while off to lunch at Astro Burger, I pulled my Smart car into the space between the house and the garage so no one could get through the gate and to the panels. There's little theft in our neighborhood, but I wasn't willing to take any chances.
Once all panels were at ground level, and before we swapped the LMUs, we discussed how best to replace the panels on the roof. The idea was that we could sort the panels so that the desired panels would be front-most in each stack ready for the swap and then lifting to the roof.
We went round-and-round: Should we replace the panels one row at a time from the top down? Should we place the panels starting at the bottom in a diagonal pattern giving a base to hold the higher panels during mounting? Or should we place panels in series order?
We made our choice, sorted the panels, and it didn't matter anyway since we changed our approach. So the panels were all out of order! It would have been better to have left them in the order we removed them from the roof. No matter. We bravely motored on.
Three panels were pulled out of the stacks at a time, I disconnected and removed the old LMUs (with my brilliant clutch drill and hex wrench), my son clipped on the new LMUs, and I connected the LMU wiring to the panels. Then Jackie (my sweetheart) helped test each panel for proper voltage output (~50VDC), I strategically placed some UV-resistant cable tie mounts on the module framing, and back up to the roof we'd go.Once we got an entire series of 8 panels re-installed we'd once again check voltages, this time looking for something in the range of 384VDC.
It was about 5 PM when we placed the last panel and sent my son back to his family. I then prepared to reconnect each series to the home-run cables to the inverter:
- DC disconnect disconnected: check!
- AC disconnect disconnected: check!
- Cable ends not laying in water in gutters: check!
- Visual inspection: check!
"It's ready to connect!" I say to myself.
A quick trip up on the scissor lift and I grab a feed from the last LMU in the first series and the matching cable from the home-run and... Huh? They don't match!
The two cables in the middle should look the same, as should the two cables on the outsides. Clearly, the connector types have changed with the new LMUs. Previously they used Tyco connectors and now they are using MC4 connectors. Well, no power to the inverter for a day or two I guess.
I dash off an email to Tigo hoping they will, once again, be able to help.
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