mount panels upside down?

[badwithusernames]

My array is 2 rows of 7 panels, one right above the other. As is the diode box and wiring is on the panel "upper edge", and once in place the top row will block access to any wiring for the bottom row. In a perfect world, I will never have to access the MC4 connectors or Tigo TS4 modules, but I'm sure that someday I will need to. If I mount the lower row upside down, I could access all of the wiring without having to remove any panels. Can anyone think of a reason not to do this?
A separate question: I do a lot of automotive and marine wiring harness work, and use dielectric grease for many weather-pack and gm delphi connectors. Do solar professionals install the MC4 connectors dry, or use any anti corrosion grease? Many of the seasoned systems I have worked upon have some oxidation inside the connectors, in spite of the o-ring seal.
Thanks in advance!

[scrambler]

The reason given in the panels manual is usually that
"This will reduce the risk of moisture ingress into the junction box"

How much of a risk that is is hard to tell

[J.P.M.]

The reason given in the panels manual is usually that
"This will reduce the risk of moisture ingress into the junction box"

How much of a risk that is is hard to tell

Condensation will will follow gravity and be present on the underside of panels and things attached to the underside of panels if/when a surface gets below the dew point and cools the entire panel as can happen with surfaces exposed to a nite sky that has an effective radiant sky temp. < the atmospheric dew point temp.

The underside of my array weeps quite often.

Think of a car's windshield in the early A.M. on a clear morning when it's humid. Same mechanism at work.

[badwithusernames]

The diode boxes/ cable connections are pretty well sealed. I've carefully opened two, and neither showed any signs of exposure. I'm thinking that as long as the box is on the underside, its is pretty well protected, and as long as it isn't at the absolute lowest point (which will catch all condensation) I may be safe.

[bob-n]

Unless there is a specific mention of installation orientation in the panel manual, either of four rotations is fine. I've never seen a panel maker specify a rotation and can't think of a reason why one is better than another, other than to keep condensation from dripping past the seals into the housings, as mentioned above. In theory, the wire entries are well sealed, so it shouldn't matter.

When we install, we rotate as needed for best wire access. That often means some panels flipped from others.

[J.P.M.]

The diode boxes/ cable connections are pretty well sealed. I've carefully opened two, and neither showed any signs of exposure. I'm thinking that as long as the box is on the underside, its is pretty well protected, and as long as it isn't at the absolute lowest point (which will catch all condensation) I may be safe.

The box design is most likely adequate for use in most any reasonably expected box orientation with respect to required protection for the box interior from liquid ingress, be that liquid from runoff or condensate, or from moisture that starts as H2O vapor in saturated air that gets into the box and can later condense inside the box.

As long as the seal(s) for liquid hold, water vapor ingress probably isn't a problem as it will, over time, migrate in, condense and evaporate out of the box as humidity and temperature conditions fluctuate. Still, common sense design considerations, including keeping things "as far up the hill" as possible (except for any weep holes, etc.), are always part of good design. For keeping liquids away from things, I always think of/like gravity and try not to put stuff where water can go.

I'd still keep in mind that since the the underside of panels will be at or close to the same temp. as the front side of panels, provided it's not precipitating, the backside of a panel whose frontside is exposed to ("sees") the night sky will condense nearly as much water vapor to liquid as the front side of the panels provided there's any reasonable air circulation under the panel. So it seems with my array.

Although I've not measured it, it might be fun to design an experiment to measure underpanel condensate mass as f(amb. conditions).

[littleharbor]

I purchased a couple hundred used panels from a lot of about 4700 panels at an almond processing plant in north central California. There were palletized panels as far as you could see. The pallets were all shrink wrapped and had been sitting for quite a few months apparently. To my surprise, when we started loading my panels it became obvious that there was a lot of water in with them. They had stacked the panels all glass side down and it had obviously rained a lot on these pallets. The panels were all nearly all FULL of water being held in the back side by the frames!

AS it turned out, the panels were all undamaged and the Tyco J-boxes were in perfect condition upon inspection. Another thing about these J-boxes that I have never seen before was the positive and negative leads were removable. They had some proprietary modular plugs from Tyco that were all removed before stacking in the pallets. I recieved a big bag of leads when I bought these panels. so even with the leads removed and fully submerged these J-boxes were completely dry when opened. I was impressed.

[J.P.M.]

I purchased a couple hundred used panels from a lot of about 4700 panels at an almond processing plant in north central California. There were palletized panels as far as you could see. The pallets were all shrink wrapped and had been sitting for quite a few months apparently. To my surprise, when we started loading my panels it became obvious that there was a lot of water in with them. They had stacked the panels all glass side down and it had obviously rained a lot on these pallets. The panels were all nearly all FULL of water being held in the back side by the frames!

AS it turned out, the panels were all undamaged and the Tyco J-boxes were in perfect condition upon inspection. Another thing about these J-boxes that I have never seen before was the positive and negative leads were removable. They had some proprietary modular plugs from Tyco that were all removed before stacking in the pallets. I recieved a big bag of leads when I bought these panels. so even with the leads removed and fully submerged these J-boxes were completely dry when opened. I was impressed.

Off hand, seems kind of dumb to store face down but it is what it is.

Any info on why they were taken out of service ?

When you write undamaged, does that mean only no obvious structural/cosmetic damage or have you checked to see if any/how many of them actually still work ?

[littleharbor]

Off hand, seems kind of dumb to store face down but it is what it is.

Any info on why they were taken out of service ?

When you write undamaged, does that mean only no obvious structural/cosmetic damage or have you checked to see if any/how many of them actually still work ?

The almond plant workers are not necessarily pro solar panel stackers.

The system was updated with high watt Sunpower panels.

I have helped a lot of folks in Baja using these panels and they haven't shown any issues whatsoever. 200 panels and not a single failure.

Not bad for $20 bucks a panel. BTW they were Trina 185 mono's

[J.P.M.]

The almond plant workers are not necessarily pro solar panel stackers.

The system was updated with high watt Sunpower panels.

I have helped a lot of folks in Baja using these panels and they haven't shown any issues whatsoever. 200 panels and not a single failure.

Not bad for $20 bucks a panel. BTW they were Trina 185 mono's

Thank you.