YES: RV Solar/ Li/ and AC running full time

[K8MEJ]

Check these standoffs out. I use Unistrut to attach to the roof. I've been saving the link to those standoffs because I might mount a new panel a little higher to clear a plumbing vent. I have not used these so I have no direct experience with them.

 

[aangel]

Thanks, @K8MEJ. Those don't quite seem high enough to get above some of the elements on my roof—even the 4.5" ones. I wish I had taken a picture the other day of the RV that had elevated panels.

 

[aangel]

Found this. Here is what I now want to do and what it sounds like @Generis is doing though without the fan shroud and I won't have a rooftop AC unit soon:

Solar panels mounted to the roof or elevated over items on the roof? - iRV2 Forums

Looking for a discussion of the pros and cons of mounting solar panels directly on the roof vs. on racks elevated over vents, A/C units, etc. assuming MPPT controller In both cases. Pros for mounting

www.irv2.com

They also installed metal deflectors to prevent tree branches from getting in:

"One nice thing about elevating them is you can clear most obstructions even MaxxAir fans which are only about 9" high when open (23"L x 16.4"W x 5"H closed; 9.3"H open). So you really can cover your roof and not raise the height any higher than a dome or trav'ler dish that's down."

Some of their panels are on a rack, others aren't.

One other person commented that doing this sort of thing (elevating the panels) is completely normal in the residential world.

 

[aangel]

Well, I've designed (and having manufactured) a bracket that will let me mount 5 panels, 78inches panel length x 1 across the roof, and then 5 panels front to back that will be 39 inches panel width x 5 (195 inches) and that's the EXACT space I have from the front fiberglass nose to the rear fiberglass cap. Exact.

Reworked my diagram using 80"x40" panels. I see the allure of getting five panels but then it seems that one is placing the mounts partially away from the corners, perhaps. Not a problem; just necessary because you're right at the limit of the roof space for the panels you are looking at—hence why you are going with something custom.

If I can get a non-custom rack that fits four of the Trinas for 1640W rated, real of perhaps:
80% x 1640W = 1312W for 5 h/day = 6560Wh

Assume 8h of AC at 500W.

Day Use:
8h x 500W = 4000Wh

Solar collection - AC load:
6560Wh - (8h x 500W) = 2560Wh available to charge the battery

Night Use:
10h x 300W = 3000Wh

But the battery is 5.1kWh. On a hot day, I won't fully recharge the battery with just four panels and if there is any cloud, forget it. I see why you are aiming for five panels.

It looks like my dream of running AC totally off solar for day and night isn't possible in really hot climates. At some point I'm going to be running the generator to help charge the battery.

That said, perhaps I can keep that down to just a dozen or two dozen days of the year. The rest of the days it might work if I can keep AC use less than the 18 h I was estimating above.

 

[Generis]

That elevated panel thing plus all the substructure is OUT for me. Way too much weight. I won't do that. I see why they did it, but I won't do that. I'm going to have a 'typical' sort of aluminum bent bracket lifting the panels off the roof. That's it. And because they will all be linked together through the brackets, there's going to be near no real weight gain. (compared to a complete structure before panels installed)

I wish I could do something of a cool drawing like you're doing, it's great to see the illustrations! My setup is to be re-layout like as follows:
Front panel 1, as you've shown with a deflector, normal bracket height of 2 inches, centered on roof
2nd panel raised 2 inches, centered and same brackets between those panels will support both of them
3rd panel raised 2 inches again, total 4 inches higher than front panel 1, over middle roof vent opening, not centered, shifted slightly passenger side 3 inches only to make room for drivers side fridge vent top. (that also makes a perfect wire transfer tube for solar stuff, which is how my wires get down)
4th panel same upper height, centered on roof
Rear 5th panel same upper height, centered again, and will cover the offset driver side roof vent.

I don't have any skylights.. my shower has a flat roof, works great for this layout (very high ceiling actually) and we have a window in our bathroom for natural lighting.

On another completely different note, I've replaced ALL of the shocks on the RV a couple of weeks ago, and OH WOW. I should have done that when I got the thing. It rides like my van now, handles corners like a champ, ZERO top heavy swaying around, and makes my stove cover bang more (hahahaha). Really worth the upgrade. I got Monroe 555031 and 555032 for the front and rear, and although the install was horrible dirty and 4 hours, it went basically without problem, and very very very worth the time and money. I mean, they were 22 years old, and it's 10,700 lbs rolling around on them things. 'Bout time.

 

[aangel]

I figured that the rack would be aluminum but I'm not attached to a rack: I just want them raised and that looked like a simple solution.

Are you thinking something like this but much taller? (From Will's page.)

You can definitely make these diagrams. It's easy and I use the free online tool:

Flowchart Maker & Online Diagram Software

draw.io

Thanks for mentioning the shocks. I am bouncing along far too much right now. I balanced the front wheels and that helped but it's still bad so I'm going to balance the rear ones, too. Perhaps new shocks will help with this issue.

 

[K8MEJ]

If you need something even taller, use those mounts on top of aluminum strut channel. You can get it in 13/16" tall and 1-5/8" tall.

 

[aangel]

Thanks, @K8MEJ , but I measured and I need at least 6" off the rooftop to do what @Generis is doing: have the panels be above my rear vent fan when the lid is about 80% open.

 

[K8MEJ]

Well, I don't have experience raising the panels that far above the roof. Will you put a wind deflector in front of the panel raised 6"?

 

[aangel]

Yes, a wind deflector that will also keep the tree branches out:

 

[aangel]

@K8MEJ @Generis the trailer fabricator who made my shelf was able to add the spare to the right vertical channel. He had some extra thick channel that is crazy strong. Instead of the typical 1/4" (I think that's what he said), it was something like 5/8". That shelf needs to hold only 100lb (albeit bouncing around) but the channel supports can probably handle 10 times that. Welded only to the frame, of course, and not attached to the RV cabin. I learned that the two are kept independent, which makes sense.

It turned out really well:



By putting the tire right in the middle, the generator box won't hit it. The shelf is above the box, too.

However, the trailer itself might hit the shelf on left turns so I'm going to buy an extended hitch with a higher ball. He didn't have one in stock but his distributor will drop ship it to me. Might save my ladder on right turns, too.

He also added another axle to the trailer and raised it by three inches to get it ready for the roads in Mexico. All in all, a very expensive trip to Salt Lake City. But this guy really knew what he was doing. I feel that the price was worth it for 30 years of experience. Plus, everyone is up to their gills in work. It almost didn't happen. He had a sub do the shelf but even after having the order for three weeks they hadn't done it two days before my departure. The owner of the trailer fabricator went to the sub in morning of the day I was leaving so that they would bend the steel as he waited. This was on his day off (last Friday).

I bought him a bottle of 11 year old Lagavulin Offerman Edition (extra peaty) to show my appreciation for his insane commitment to customer service but he doesn't drink any longer. I'll find a nice restaurant to treat him and his wife.

As a side note, I have an extra 3000 lbs to tow. Can I fit a hot tub in there?

Below: notice how the trailer is tilted forward. The raised ball hitch will rectify that.

 

[K8MEJ]

@aangel That's fantastic. Please show us the final result when you're finished. May I ask, why are you going to Mexico? Do you think a weight distributing hitch will help? That trailer looks nearly as long as your RV, but I can't remember if you have a Class A or a Class C. I'm eager to see the new air conditioner installed.

 

[aangel]

@K8MEJ I will definitely update y'all on the final result. Getting solar going is required before I head south.

I'm going to spend a few months in Baja to enjoy the weather, the environment and the culture. Plus, since I have my bike, I'll do some off-road riding, too.

I haven't looked into a weight-distributing hitch. I keep hearing about those. I'll do some research on it. I have a 23ft Class C and the trailer is 14ft. I have to be careful while turning.

 

[K8MEJ]

It's important to know the tongue weight of your trailer (when loaded), the max tongue weight your RV hitch is rated to handle, and maximum towing weight. These should be on a sticker on the hitch on the RV. You also need to know if your RV frame is rated for a weight distributing hitch (WDH). That will be in your owner's manual.

If all the above is checked out and a WDH is approved for your RV chassis, I think you'll find the WDH will improve your towing experience and will minimize sway. Any decent trailer shop can help with this. Even though I tow my 32' travel trailer with an F-350, I still use a WDH when traveling at highway speeds. It removes any sway and makes towing more relaxing.

 

[eXodus]

He also added another axle to the trailer and raised it by three inches to get it ready for the roads in Mexico.

It looks like the axle could have gone more forward - That way you would be not putting as much weight in the hitch. Be careful about the weight distribution inside the trailer now.

If all the above is checked out and a WDH is approved for your RV chassis, I think you'll find the WDH will improve your towing experience and will minimize sway.

very few Class C RV chassis are approved for WDH. Some Class A are - but those are usually so heavy that you don't need sway control

This trailer is so long in front of the axles - it should have minimal sway. Travel trailers have a lot of length behind the axles - they need WD - but Cargo Trailers and Horse Trailers with almost no overhang behind the axles - are very stable.

Further not all WDH are also reducing sway - many have this function included through friction - but you can also just get a Sway control hitch without WD.

 

[Lt.Dan]

The further back the axle, the better imo. It really helps reduce sway and as long as you dont overload the tongue rating, it will make for a much better towing experience. If I could move the first (forward) axle on my 5th wheel behind the 3rd (last), I would do it in a heartbeat.

 

[chrisski]

I like the idea of adding a second axle to a trailer to increase the weight rating, especially after seeing how limited I would be with weight ratings if a take the typical open trailer for sale and turn it into a enclosed RV. Same problem with the enclosed trailers: A 10k trailer is actually only good to tow 5k because it weighs 5K.

Butt…

If I add the axle will I gain any LEGAL towing capacity or will I just get a smoother ride?

My guess is adding an extra axle will not let me tow any more than the sticker weight of a trailer unless I get it “Inspected, and restickered,” which those businesses are probably hard to find if they even exist.

Not to hijack the thread, but my plans to build my own RV are on hold because of these weight limits.

 

[aangel]

Down in Corpus Christi now in 80° days and trying to eat all the seafood. The trailer had little sway on the way down—much less than when I had just one axle. So in the sway department it's handling well. However, I did get a blown tire and I wonder if the extra weight was the cause or if I hit something. When I last checked the tread it seemed adequate.

@eXodus I agree that the axles could have been placed more forward but the installer said that he had structural elements under the trailer that made that problematic.

And thanks to both of you for the suggestion to look into a weight-distributing hitch. I had thought that raising the rear end via the airbags would be enough but these two videos showed me that the hitch really does cause more weight to go to the front (which simply raising the rear with airbags does not do). My front-end is already light when towing and will be even lighter because of the weight I'm adding with the compressor unit. In a hard braking situation the trailer makes the situation worse because the weight of the trailer presses down on the rear of the RV.

Spring Bar Vs Airbags in Weight Distribution

The Difference Between Using Weight Distribution and Air Bags to Level Your Load

I have an appointment tomorrow with a shop that installs hitches and another shop that installs shocks and will inspect the airbags and get them back into play. I suspect that my generator box is going to get in the way of the hitch so crossing my fingers.

If I can install any hitch at all, the dealer says he can get his hands on a Tru Track that will allow me to reverse with the WDH installed.

 

[richard cabesa]

Wheel alignment on a tandem axle trailer is VERY important. Have it checked and make sure it is perfect!

What happens when it is not is a blown tire.

Someone smacks a curb or abject turning into a gas station or where ever and doesn't think much of it. That tire could now be just a degree or so out of line. The other three carry on straight down the highway while that one is being drug "sideways". It will scrub the tread off, over heat and blow in very short order.

For that matter, make sure your fabricator got the new axle in parallel to the original.

 

[aangel]

Very interesting, @richard cabesa . My original axle had gotten out of alignment and I did not correct it after adding the second one. When I visit the trailer shop I will get them to look at it. They might have to bend the axle back to true—or maybe only the wheels are out of alignment.