Since I'm committed to 12 volt because of a pure sine wave inverter, if I upgrade I will go MPPT with the Magnum PT-100. That would allow me to install 1200 watts of solar. To do that would require a roof rack that goes above the air conditioner.How much clearance would I need above the air conditioner shroud? I will have a way to remove the panel(s) that cover the conditioner.How would you secure the rack to the roof?The RV in question is a 28'5" class C.

pianotuna wrote:Since I'm committed to 12 volt because of a pure sine wave inverter, if I upgrade I will go MPPT with the Magnum PT-100. That would allow me to install 1200 watts of solar. That is a lot of solar, what are you using for a battery bank?I don't know how tall your RV is but I would keep the panels less than 13' off the ground or 3" - 4" above the AC.

Don When I ever get enough money to do solar I am pretty sure I will go with the lightweight UNISTRUT channels... We used to build everything with UNISTRUT and with the ability to slide things around before tighting the screws might be a good thing with the solar panels..I can't even think about how much weigh your 1200WATTS of solar is going to have...About all of the room I have on my OFF-ROAD POPUP trailer roof will only safely support maybe three 120WATT panels.Then the other problem I know I am going to run into is raising my roof with my electric motor... This may require me to not mount two of these 120WATT solar panels until after I raise the roof first and lock in place. This could easily done with two of my 120WATT panels that I can step into the front deck and should be able to mount them with ease. The sliding nuts of the unistrut should be a real help here as well...Two panels on the front on each side of the fantastic fanOne panel going across the rear of the roof between the A/C and the roof edge...The other advantage of mounting the UNISTRUT channels across the roof is I can attach these going into the side roof thick supports. I'm always leary of doing anything to the roof top areas...Hope your panels going on top of the a/c units will keep you under the 12-13 foot height restriction going down the public roads... I also think you are going to have some strange wind load buffeting going down the roadways with that much distance under your panels... That would scare me especially passing big trucks that might be pushing a head wind of 50-60mph... Roy Ken

Pianotuna, I don't know about your trailer but you might think about a rack that attaches to the sidewall of the trailer rather than the roof. This way you may be able to use a little larger supports. I have attached this link that shows a roof rack for horse trailers to haul hay. Only reason is to show that they are attached to the sidewall and don't have to drill into the roof. You don't mention if the trailer will be moved but if it is and the panels are up in the air you will need a little more sturdy supports to handle wind whipping up under. Another option is the attach the panels to the top side of the trailer and lift them up from the bottom when you get parked to whatever angle you want them. Both these options require no drilling into your roof.clicky

Sure, you can fabricate a rack over the AC unit to hold a module. It can be built of off-the-shelf structural aluminum channels. The rack would be attached through the roof decking into a frame piece.Now, we could discuss the appropriateness of such hardware--In the most typical instance, one module would be mounted like this. Can you suffer the loss of one module? Can a module be mounted either on the side, ala awning type, or could it be portable? I would suggest to think of alternate methods before building a rack over the AC. There are complexity and use considerations that need to be overcome.

Sounds scary pt. More wind load, and, significantly raising the roof clearance height.

roof rack for solar | Good Sam Community

BoonHauler
Explorer
Mar 29, 2016
Don:

Does your A/C have rear or top discharge?

My A/C has a top discharge, that's why I'm asking.
Dranoel
Explorer
Mar 29, 2016
The current necessary for electric heat or A/C would quickly deplete your batteries. You'll need a generator for those.
pianotuna
Nomad III
Mar 29, 2016
Hi,

I think it is rear--there is no venting on the top of the shroud.

BoonHauler wrote:
Don:

Does your A/C have rear or top discharge?

My A/C has a top discharge, that's why I'm asking.
pianotuna
Nomad III
Mar 29, 2016
I'm aware of the energy needs of resistance heating and have 3 years of data to draw conclusions from. I want to extend the time before I have to connect to shore power.

I can heat 100% electrically on a single 15 amp circuit in mid October. Adding solar to the mix may extend that a couple of weeks and probably would mean I don't need to use shore power at all in September. Of course, no one can predict the weather.
pianotuna
Nomad III
Mar 29, 2016
Hi,

The hay rack looks interesting but is too narrow for my RV.
MrWizard
Moderator
Mar 29, 2016
Unfortunate the width prevents me from hanging panels off the sides--I'd be over the legal limit.

This does not compute
A rolled up awning sticks out further than a folded flat solar panel flat against the side of the RV
Your mirrors stick out further than the awnings
Legal width limits apply to the solid body
Attachments that are under the width of the mirrors are legal
lc0338
Explorer
Mar 29, 2016
Here is a visual
lc0338
Explorer
Mar 29, 2016
I don't think as long as the panels are parallel with the roof there will be a lot of wind issue. Yes, there will be some gusts upward but my solar generator panels entend above the roof of my truck cab. Of course if Don mounts above the AC unit there will be more distance between panels and roof than my unit. But... I would not put that much weight and wind gust load with attachment to the roof. I would only mount from side of trailer (like the hay rak system). Here is a picture of my solar generator on my truck. There are 2ea 270 watt panels and on my regular cab they completely covered my cab and front edge was out over my hood. On my new truck (crew cab) the leading edge of the panels reach about the front of the cab clicky
BoonHauler
Explorer
Mar 30, 2016
pianotuna wrote:
Hi,

I think it is rear--there is no venting on the top of the shroud.

BoonHauler wrote:
Don:

Does your A/C have rear or top discharge?

My A/C has a top discharge, that's why I'm asking.

If it's not top discharge I'd say go for it. As for the structure to hold the panels, I'd say aluminum channel would work well. I didn't get a chance to look at that light weight super strut mentioned above but that might be a good option as well.

To me the bigger deal is making a good connection to the structural support members in your RV's roof.

Good Luck and post few pics when you get it built. I'm sure there's more than myself that would like to see it.

Cee

PS: I'm looking (in the not too distant future) to change out my MS inverter for an MSH. You and I have a lot in common although I'll stay away from the resistance heating.
pianotuna
Nomad III
Mar 30, 2016
Hi Mr Wizard,

The mirrors apparently do not count. Nor do awnings. I've thought about hanging panels from the sides. If someone would finally make a truly flexible panel, I would replace the awning in a flash.

MrWizard wrote:

This does not compute
A rolled up awning sticks out further than a folded flat solar panel flat against the side of the RV
Your mirrors stick out further than the awnings
Legal width limits apply to the solid body
Attachments that are under the width of the mirrors are legal

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