No generator, no problem!

[Suprasoup]

I was driving behind a sprinter van when his panel let loose on I-70 in Colorado. He had left it tilted and a strong cross wind ripped it off his roof. Another time was in NM on the way back from AZ. The RVer had installed his panel mounts (Z mounts) using VHB tape. The VHB tape gave and the panel ripped. Landed probably 100ft from my truck. Chocolate brownie moment for me.

I wouldnt call them frequent but I do seem to see them at least once or twice a year in the Southwest. Up there with kayaks and paddleboards flying off roof racks.

[Wrybread]

'm not the world's engineering police , but saying something works just fine now gives you some responsibility for what others reading your stuff may go and do.

I definitely wasn't saying to take mounting the panels lightly. I was saying it's easy to do well using the existing time tested methods. People definitely need to do a bit of homework when mounting panels. For my part, the easiest and safest method I've found is to use purpose built solar panel mounts, follow their instructions, use common sense with mounting points, and use a through bolt and a backing plate if you don't trust your roof's integrity. And a really nice thing to do is add a safety tether made from stainless airplane cable on each panel so even if a panel does somehow come loose it can't go far. Hell even a piece of rope or ratchet strap webbing would do it, but obviously fibers break down quickly on the roof of an RV and you want something that will last years, which is why I like to use airplane cable.

And for whatever it's worth I've logged probably hundreds of thousands of roadtrip miles, all around America, Canada, Mexico, a bit of Guatemala, and Europe, in heavy RV areas and have never seen a panel fly off a roof. Not to say it doesn't happen, but I must be really lucky... Well technically it did happen to a camper some friends and I used to store in La Paz, Mexico for surf trips, when a hurricane tore the storage area to shreds. But that took off the whole roof of our camper so I'm not sure that counts... The panel was still clinging to that roof though, amazingly enough.

[Suprasoup]

i have seen panels flying off RVs, Sprinter vans, campers often enough that I would take the safety consideration seriously. Thread locking compound on all the bolts are your friend. Something about the vibration on onroad/off-road vehicles tends to loosen bolts over time. I periodically check the ones on the trailer before travel just in case.

Last thing you want is to injure or kill someone.

[J.P.M.]

Out of curiosity, do you own an RV?


In real world use it works just fine.

Since you ask, no, only one eye, one balloon knot and a fair amount of experience designing structures for wind and other external loads.

As for it working just fine, I'm sure it does and will continue to do so until it doesn't.

I'm not the world's engineering police , but saying something works just fine now gives you some responsibility for what others reading your stuff may go and do.

But, NOMB. Your RV/life/whatever.

Take what you want of the above. Scrap the rest.

[Wrybread]

Also, what happens if you're driving at 60 MPH into a 40 MPH headwind, etc. ?

Out of curiosity, do you own an RV? Of course we've all been in the above situation a million times, never so much as a whimper from my panels.

BTW, it's probably not the best thing for the panels to have stink/moisture vents under them. Doing so will also probably/potentially screw up the draw for the vents.

In real world use it works just fine. Solar panels are tough and a little extra air flow on their back sides is probably actually *good* for them. And as long as you leave a little gap over the top of the vents (duh) those vents work just as well as before they had panels over them. Again there's no reason to get theoretical here, there's lots of people who've been mounting solar panels on their RVs and trailers for decades without any problem from the above.

That's not to say people don't have to be careful when mounting panels of course, but it's super super super easy to do well. I've had good luck with this stuff:

https://www.amazon.com/Solar-Mounting-Bracket-Supporting-Brackets/dp/B07FY32KFJ

(Or lately I just cut beefy aluminum angle iron into short strips, which is even easier to work with)

And then cover the screws with good ol Dicor Lap Sealant:

https://www.amazon.com/Dicor-501LSW-1-Self-Leveling-Sealant-10-3-Fluid_Ounces/dp/B000BRF7QE

[J.P.M.]

Plumbing vents and ceiling vents will come after the panels. I am dealing with a less than ideal environment and trying to make up for it by overpaneling. I have roughly 8' x 35' space to work with.

I am not entirely sure what the wind rating is. I expect them to be able to tolerate the 65mph wind. That would be a common condition when mounted on my house.

Well, this is not a stationary mounting. The panels will usually take a wind load. It's the design and method of attachment(s) that are usually overlooked that usually causes more problems, particularly if the panel supports are designed to be off horizontal when stationary. Also, what happens if you're driving at 60 MPH into a 40 MPH headwind, etc. ?

BTW, it's probably not the best thing for the panels to have stink/moisture vents under them. Doing so will also probably/potentially screw up the draw for the vents.

[PNW_Steve]

Ha!



My rig is a 24 foot class C. I had to cover two plumbing vents to fit my three 310 watt panels, but they were just pvc pipes with lids that were easily sawed off making the panels the new lids. One of my panels overhangs a few inches over my passenger side and had to be mounted at a slight angle to make things fit, but other than being a bit of an eyesore (I actually think it looks beautiful, ha) it's no biggie since the side mirror sticks out way more. And of course it's a small price to pay for near infinite power.

I keep meaning to install a 4th panel, but that means either losing the loveseat that I keep permanently mounted on my roof's cargo area (at the rear where the rack is), or covering the light vent (the kind that cranks open) above my shower. There's no urgency since my 3 panels give me all the power I need even through winters, but I'm totally off-grid with no generator or connection to my alternator (I never run my engine anyway) so an extra panel would come in handy in the dead of January when we get stormy weather for weeks at a time. There's no urgency since my system has gotten me through 3 winters in a row at this point, but I'm a bit worried about my battery bank (4 Trojan T-105s) since they're now either 5 or 6 years old, which is obviously pretty long in the tooth. And I'm a huge fan of being able to get maximum charge during those tiny breaks in the storms.

Are you running all your panels into a single charge controller, or breaking things up into multiple? I'm using a single Morningstar MPPT-60, before that a Tracer 40 amp MPPT. The Tracer worked fine but the Morningstar fell into my lap. And what's your battery bank?

I am using the Midnite Classic. If I add two more panels I will probably need a second charge controller.

[Wrybread]

When you are charging well, what sort of PV harvest do you see, 300w? 500w?

@Mike90250: By the way I was wrong when I responded earlier saying I get about 500 watts max. I hardly ever look at my charge rate anymore since it's all set-it-and-forget-it, but your question made me watch more. I've been getting a max of 650 watts (about 50 amps @ 12 volts). Once this battery bank dies I'll either go 24 volt lead acid or, hopefully, high voltage lithium, which should get me a significantly higher charging rate. But what I'm getting has been working really well for me so no biggie.

[Wrybread]

After many years in the casino industry I discovered the only machine in the casino that paid out regularly was the on with the big sign above it "ATM".

Ha!

What sort of rig are you installing solar on?

My rig is a 24 foot class C. I had to cover two plumbing vents to fit my three 310 watt panels, but they were just pvc pipes with lids that were easily sawed off making the panels the new lids. One of my panels overhangs a few inches over my passenger side and had to be mounted at a slight angle to make things fit, but other than being a bit of an eyesore (I actually think it looks beautiful, ha) it's no biggie since the side mirror sticks out way more. And of course it's a small price to pay for near infinite power.

I keep meaning to install a 4th panel, but that means either losing the loveseat that I keep permanently mounted on my roof's cargo area (at the rear where the rack is), or covering the light vent (the kind that cranks open) above my shower. There's no urgency since my 3 panels give me all the power I need even through winters, but I'm totally off-grid with no generator or connection to my alternator (I never run my engine anyway) so an extra panel would come in handy in the dead of January when we get stormy weather for weeks at a time. There's no urgency since my system has gotten me through 3 winters in a row at this point, but I'm a bit worried about my battery bank (4 Trojan T-105s) since they're now either 5 or 6 years old, which is obviously pretty long in the tooth. And I'm a huge fan of being able to get maximum charge during those tiny breaks in the storms.

Are you running all your panels into a single charge controller, or breaking things up into multiple? I'm using a single Morningstar MPPT-60, before that a Tracer 40 amp MPPT. The Tracer worked fine but the Morningstar fell into my lap. And what's your battery bank?

[Wrybread]

Where I spend most of my time we get insane winds from the south during storms. My weather station registered gusts to 80 knots during one of them. Somewhat funny aside: my neighbor was installing four 280 watt panels on his new-to-him RV a few months ago (280 watts because he's that cheap, I think they were $80 each), and they weren't bolted down yet. Right when the front was passing and all hell was breaking loose his panels started flying into my camper! Just missed one of my windows. That sucked.

But I've never had, or heard of, a problem with bolted down panels, on any RV whether it's stationary or driving through super heavy Santa Anna winds. I'm embarassed to admit I've lost multiple surfboards off my roof, but never a solar panel, in 25 years of having them up there.

[PNW_Steve]

A decent 300 STC W panel rates out at ~ 17.1 STC W/ft.^2. --->>> 2400 STC W/17.1 STC W/ft.^2/ = ~ 140ft.^2 clear of shading and obstructions when horizontal. Might work, depending on vents/penetrations/vehicle size. Don't know what a design that considered wind loads might require.

Plumbing vents and ceiling vents will come after the panels. I am dealing with a less than ideal environment and trying to make up for it by overpaneling. I have roughly 8' x 35' space to work with.

I am not entirely sure what the wind rating is. I expect them to be able to tolerate the 65mph wind. That would be a common condition when mounted on my house.

[Wrybread]

A decent 300 STC W panel rates out at ~ 17.1 STC W/ft.^2. --->>> 2400 STC W/17.1 STC W/ft.^2/ = ~ 140ft.^2 clear of shading and obstructions when horizontal. Might work, depending on vents/penetrations/vehicle size. Don't know what a design that considered wind loads might require

Odd to see it written as if we're reinventing the wheel here... This is all really basic stuff.

[J.P.M.]

I must be extremely lucky.....

I am trying to decide whether the 1800 watts of panels on the roof is enough. Maybe I should go 2400?

I have the room and I have the panels. Hmmmmm...

A decent 300 STC W panel rates out at ~ 17.1 STC W/ft.^2. --->>> 2400 STC W/17.1 STC W/ft.^2/ = ~ 140ft.^2 clear of shading and obstructions when horizontal. Might work, depending on vents/penetrations/vehicle size. Don't know what a design that considered wind loads might require.

[PNW_Steve]

Ha! It seems like a lot of us keep getting extremely lucky around here. The way we keep beating all these impossible odds we should all meet up in Vegas!

Have fun with that

After many years in the casino industry I discovered the only machine in the casino that paid out regularly was the on with the big sign above it "ATM".

What sort of rig are you installing solar on?

[Wrybread]

Ha! It seems like a lot of us keep getting extremely lucky around here. The way we keep beating all these impossible odds we should all meet up in Vegas!