Mounting Solar Panels

[Lin]

I am just replacing the shrouds on my old Coleman AC's.  The shrouds are secured to the unit with four bolts and are quite stable, so I was thinking that I could mount a small solar panel, about 2'x3', on the top of each one quite easily.  This would give me about 10 amps of charging, which would top off my batteries after the morning run of the generator for hot water and bulk charging.  Any thoughts on this scheme would be welcome.

[luvrbus]

The heat from the solar panels will destroy you AC shrouds BTDT 

[Lin]

BTDT? Really?  Interesting--how hot do those suckers get? Would putting some insulation like that foil bubble stuff do any good? By the way, these are Tuf-Max shrouds so they are supposed to be much stronger than OEM.

[luvrbus]

I tried foil and it killed the panels I guess they didn't care for it much

[Utahclaimjumper]

 I have one on each of my A/Cs, came standard on most early American coaches, they put out very low current and don't make much difference.>>>Dan ( I have three panels for 300 watts per hour arranged on the roof)(That DOES make a difference, your not going to find that free lunch)

[Lostranger]

The heat from the solar panels will destroy you AC shrouds BTDT 

That's rich! Not only do solar panels not produce noticeable heat, they shade what's beneath them and make it cooler. I do not understand what the original poster is intending to do, but the only way I could imagine a heat issue is if he somehow blocks his AC vents.

Jim H.

[Lin]

Jim, the thought is to merely mount small panels on top of the AC shrouds since they would be secure enough.  This would leave the roof a bit less cluttered and avoid putting more holes in it.  I had not considered a heat issue.  What would the surface temperature of a panel be on a good hot, desert day?  What would the temperature be on the rear of the panel?   

[luvrbus]

Depends on the type Jim the ones for electrical the more heat they produce the less watts they produce mine were for producing hot water they got hot as hell. 

They get hot here in the desert Lin and the AC blowing hot air doesn't help mine is close to AC  it gets hot and wasn't a cheap panel    

[Iceni John]

You should always allow free air space under the PV panels to help prevent heat buildup.   Mounting them flat on anything, especially a heat-producer like an A/C, will cut their output.   For example, my Sharp 250W panels lose almost half a percent power output per degree Celsius as they get hotter:  http://files.sharpusa.com/Downloads/Solar/Products/sol_dow_ND250QCS.pdf

Make sure to secure those panels well  -  desert gusts can easily rip panels off roofs if they're not well secured.

What charge controller are you using?   I'm thinking of using the Morningstar SunSaver Duo with a small dedicated PV panel just for keeping my starting batteries fully charged:  http://www.morningstarcorp.com/products/sunsaver-duo/   This would be completely separate from my main PV system for house power.

John

[Dlsnow]

We have both water and electric solar on our bus and they both do get hot

-We read a surface temp of 190 on the water one
-not sure the exact temp on the electric but we wipe them down every few months I would guess they are over 150

-in the desert in the winter so figure ambient temp in the 70's but with direct sun all day long

FWIW

-Dave

[Zephod]

You should always allow free air space under the PV panels to help prevent heat buildup.   Mounting them flat on anything, especially a heat-producer like an A/C, will cut their output.   For example, my Sharp 250W panels lose almost half a percent power output per degree Celsius as they get hotter:  http://files.sharpusa.com/Downloads/Solar/Products/sol_dow_ND250QCS.pdf

Make sure to secure those panels well  -  desert gusts can easily rip panels off roofs if they're not well secured.

What charge controller are you using?   I'm thinking of using the Morningstar SunSaver Duo with a small dedicated PV panel just for keeping my starting batteries fully charged:  http://www.morningstarcorp.com/products/sunsaver-duo/   This would be completely separate from my main PV system for house power.

John

How do you secure solar panels? I have a curved roof and was thinking of a few panels end to end. Securing them possibly with rivnuts and m5 bolts. The ventilation I understand but how to baffle the gap so that strong winds won't rip them off?

Waterproofing the rivnuts will be done with silicone caulk.

[Iceni John]

My Crown has a very curved roof, similar to most older GMs, so I used that to my advantage.   I first made a 26'-long walkway that goes between my two roof hatches;  this walkway is bolted through every roof rib (every 19") with 3/8" stainless socket-head bolts from underneath, so 36 bolts hold this walkway in place.   Watertight sealing is by EPDM washers between the roof and the stainless washers under the spacers that hold the walkway about 4" above the roof.   This walkway is made from 6061 angle and aluminum treadplate, cross-braced at every rib to prevent any movement, with removable access to the five combiner boxes underneath it for the PV panels' wiring and for the eventual solar water heating panels.   From this walkway are hinged eight support frames for my PV panels;  each frame is made from 6063 angle with SS hinges.   Each frame can be lifted up to 45 degrees above horizontal for ideal winter insolation, but stow down against the roof at 22 degrees below horizontal when driving or for summer insolation.   The frames' support struts are telescoping stainless-steel that hinge and pivot at both ends and slide in T-track on the bottom, with additional clamps for securing them down when driving.   During the recent heavy rains I had NO leaks or drips through the roof, so I know my system of using EPDM washers as seals works well, and it's simple and cheap and (I hope) maintenance-free.

John