Caught in downpour during second day of installation

[hifi239]

Hi,

I recently had a solar system installed on my roof. The installers put up the rack on the first day, but I was surprised that with some rain forecast the second day the installers continued with the panel install and wiring. They got all the optimizers in place and half the panels up when a one-hour downpour rolled through. The exposed half of the optimizers with uncapped MC4 connectors got rained on. Then after the rain, the installers finished the panel install. After a few weeks everything is working fine, but how worried should I be? Is there water trapped in the sealed MC4 connectors? Will the trapped water eventually corrode the connectors? Or will a few 80-degree days cook the water out?

Generally I see the connectors as a weak point in long term reliability. I have long warranties on the panels, the optimizers and the inverter, but if the connectors corrode after a decade that is a huge job to rebuild the system. No?

Thanks in advance.

Will

[kb58]

If you can access the connections, unplug them for a few days. If they're really sealed connectors, no, the moisture won't just go away. The real question is was water able to get past the connectors and wick down the wire conductors.

[sensij]

The contacts inside the MC4 connectors will absolutely corrode when wet and exposed. I left a couple of optimizers out overnight with uncapped ends, and just from the morning dew there was visible dulling / discoloring of the contact surface visible looking into the end of the connector. After that experiment, I made sure my optimizer leads were always connected together when outside.

How many optimizers were exposed during the rain?

You might consider inspecting the connectors on one of the optimizers you know was exposed. See if you can detect water still in there, but I bet the corrosion will already be obvious.

bcroe has investigated this more than most, and might have some ideas on how the long term performance could be affected.

[bcroe]

The contacts inside the MC4 connectors will absolutely corrode when wet and exposed. I left a couple of optimizers out overnight with uncapped ends, and just from the morning dew there was visible dulling / discoloring of the contact surface visible looking into the end of the connector. After that experiment, I made sure my optimizer leads were always connected together when outside.

How many optimizers were exposed during the rain?

You might consider inspecting the connectors on one of the optimizers you know was exposed. See if you can detect water still in there, but I bet the corrosion will already be obvious.

bcroe has investigated this more than most, and might have some ideas on how the long term performance could be affected.

I agree, don't leave those MC4s disconnected outdoors (the only place they are found here). Since its
brand new, I'd probably break that whole system apart, and try a hair dryer to dry them out. Being
sealed they might be OK. If there are long term failures, the connector will be running warm/hot under
best sun. MC4s aren't hard to replace if you have any length to spare, but inconvenient.

I have devised some dummy MC4s with the wire end plugged and the latches ground off. These are
slid onto any temporarily exposed MC4s to keep them sealed at all times. Do remember that an array
can produce lethal voltages; I usually start by breaking it into a few isolated sections; frequently just
use lights at night. Bruce Roe

[hifi239]

Thanks very much for the info. I would not be doing any of the work. My wife would never let me go up on our 45-degree roof. This job was done by a reputable installer in the Boston area and I now have some intelligent facts to discuss with their management. Perhaps they will come back and disassemble the portion in question and dry out the connectors. I believe they got the top row of nine panels done before the rainstorm and that 13 out of 22 optimizers with dangling connectors got rained on. Yes the long term fix later if it fails would be to remove each panel and cut and replace the connectors. Otherwise it's been great. Just got a string of 40 KWh days here.

[Mike90250]

And never, ever open a MC solar connector when the sun is out, the resulting high voltage DC arc will ruin the contacts in a second.

[max2k]

And never, ever open a MC solar connector when the sun is out, the resulting high voltage DC arc will ruin the contacts in a second.

... when the current is flowing through that connector. When the current is 0 (AC / DC disconnects are off and nothing is consuming the energy) they can be opened without causing arc damage.

[Mike90250]

... when the current is flowing through that connector. When the current is 0 (AC / DC disconnects are off and nothing is consuming the energy) they can be opened without causing arc damage.

You and I know that, but the safe path is to advise against opening them when illuminated. "I turned the loads off, but the thing still arced" Oh, you mean all the loads, not just the __?

[hifi239]

OP here with a follow-up. After some balking the installers have agreed to replace the 13 optimizers whose connectors were exposed to heavy rain and wind just prior to assembly, along with the corresponding 13 PV modules. Aside from the inputs here, one helpful factor was that SolarEdge manuals, as confirmed by a tech rep, state categorically that their warranty is void in such case. All the installers needed to do in my case is plug the optimizer connectors into each other for the duration of the rain, but they did not. Cheers...