solar panel roof mount frugally? Cathodic reaction issue?

[NM_Shooter]

Got a quote from the solar place on what they think it will cost to mount my single panel on my roof. 

$120 for the hardware, $100 for the MC4 cable and Assembly tool. 

Seems like a lot.

I'm considering just building my own bracket on the roof out of uni-strut material that I already have here.  It will be under the panel (for the most part) so the ugly factor will be reduced. 

Questions for you to comment on...

1)  I'll have an aluminum frame PV panel, touching both galvanized metal and stainless bolts.  Is a cathodic reaction a danger?   Or do I only have to worry if I am using copper to steel?

2)  I'm thinking of running two or more unistrut sections parallel to the ribs on my pro-panel, and lag bolting the unistrut through the roof deck and reinforcing with some plate metal on the inside of the attic.  I figure I'll cut rubber washers 1/4" thick and silicone them onto the roof.  When I bolt through, the washer will squish down and help seal the hole. 

3)  I'm going to use 10/2 UF Romex.  Any issues with running this inside the wall to where it will exit to my power box?  I'm guessing max amperage will be 8A if I am lucky.  Only a 25' run.

[Onkeludo2]

I cannot help you with the rest, but you will have a dissimilar metals issue with aluminum and steel.  How severe will it be?  That depends but most likely minimal.

Your panels need to be bonded to the mounts (heavy ground wire joining all th parts) which takes away 90 percent of the risk.  Another option is use a piece of 30# felt between the frame and the mount then you only have to worry about the bolts themselves.

Mike

[Proud_Poppa]

Is there any chance of ground mounting it? This would give you better access for cleaning and maintenance and if you do a little planning you can design a seasonal tilting adjustment. A good looking mount could be made from treated lumber. I used to have my single pv panel (Only used for amateur radio backup power) hanging off one edge of the deck. It worked great and it was easy to brush the snow off!

[NM_Shooter]

I'd like to ground mount it, but due to the sheer amount of snowmobile tresspassing, I suspect that it would not be there in the spring. 

Hmmm... maybe I should just pony up for the aluminum mounting hardware and be done with it.

-f-

[MountainDon]

I'd use something non absorbent for an insulating spacer in place of felt. With all the rain no sense in making a battery with something wet inbetween the metals. Rubber plus stainless bolts should be fine. Or the buy the real thing so you don't have to mess around. 

[NM_Shooter]

Yes, I think I will just buy the real thing!

[glenn kangiser]

Properly harnessed, the cathodic reaction could assist in charging the batteries.... but tough luck on the frame, eh?

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