[arthurdeernuts]

Hi!
I'm planning on mounting two Solaria PowerXT-400R-PM panels to my 2020 EL Transit. Each is roughly 64 3/4" x 47 1/2". The panel's long sides would span the width of the roof with their ends hanging over the middle of the 1.5" wide roof edge grooves. I would mount them directly to the roof with 1/8" aluminum Z brackets fabricated from two pieces of aluminum angle, similar to how Orton did his: Solar System | Orton Travel Transit

The panels I've seen are elevated an inch or so from the roof, I assume to allow air entry for cooling. But since the roof is crowned and I am mounting across the width, couldn't I mount the center of the panel frame directly to the center of the roof? Only a few inches away the gap would reappear and grow to 2 or 3 inches at the roof sides.

While reading about making a wind fairing for the front, Test of fairings on solar panels to reduce drag I also saw that it may help a lot to make a rear exit fairing as well as side fairings to prevent drag from the underside of the panel. This wouldn't be hard to do but I'm concerned about restricting cooling air flow when I'm parked. I could also but the panels together to save space and prevent drag, but am concerned again about heat dissipation.

Thoughts?

 

[jkmann]

There is a tradeoff involved in putting the solar panels very close to the roof: pro: reduces drag, and, looks a bit nicer. cons: gets hotter under the panel, and that heat transfers into the van; and, solar panel output (and longevity) declines with heat. Once you add a fan or air conditioner, you have already disrupted any hope of laminar flow over the roof. So, for most people, there is a risk of overthinking on this problem.

Although it's interesting to try to optimize the mounting of solar panels, if you are really concerned about this, flexible solar panels will offer a dramatic improvement, far beyond anything you could get with a fairing.

 

[orton]

I would mount the panels close to the roof at the center without touching the roof. Only do a fairing if after the install you have wind noise. No noise from my panel without a fairing but my panel is only 39.37" wide.

 

[arthurdeernuts]

Yes, if it's not broke, don't fix it. thanks. Why do you say don't touch the roof?

 

[orton]

Yes, if it's not broke, don't fix it. thanks. Why do you say don't touch the roof?

I suspect vibration would probably wear off the paint. Just need very little clearance.

 

[gregoryx]

Hi!
I'm planning on mounting two Solaria PowerXT-400R-PM panels to my 2020 EL Transit. Each is roughly 64 3/4" x 47 1/2". The panel's long sides would span the width of the roof with their ends hanging over the middle of the 1.5" wide roof edge grooves. I would mount them directly to the roof with 1/8" aluminum Z brackets fabricated from two pieces of aluminum angle, similar to how Orton did his: Solar System | Orton Travel Transit

The panels I've seen are elevated an inch or so from the roof, I assume to allow air entry for cooling. But since the roof is crowned and I am mounting across the width, couldn't I mount the center of the panel frame directly to the center of the roof? Only a few inches away the gap would reappear and grow to 2 or 3 inches at the roof sides.

While reading about making a wind fairing for the front, Test of fairings on solar panels to reduce drag I also saw that it may help a lot to make a rear exit fairing as well as side fairings to prevent drag from the underside of the panel. This wouldn't be hard to do but I'm concerned about restricting cooling air flow when I'm parked. I could also but the panels together to save space and prevent drag, but am concerned again about heat dissipation.

Thoughts?

Thanks for the link to that test. Pretty interesting. We've postponed a planned fairing in the front since they don't make noise. But if I can figure out what-all he's talking about in that test, I'll revisit the fairings or whatever. Nice to think we'd possibly get 1mpg back (since we lost two when the panels went up). 🤔

All that said... I agree with @orton: I don't think mounting them particularly high gains anything. The panels are at the top of the typical 1.5" high frames, so any airflow at all should suffice to keep it evacuating under the panels themselves.

Of course, @jkmann's flexible panels are probably one of the best for air-flow / resistance. And he's posted before about mounting them on another surface to encourage cooling. I still find it pretty unlikely that they last very long (ours didn't); but my buddy is still getting 70-80% power from his after 5-6 years, so... 🤷‍♀️

Ours are currently mounted in a huge frame to be able to tilt the whole deal. But after finding how much power we're pulling from the engine (when necessary) and that the non-winter-storm generation is really awesome, we'll plan to dump the frame and drop the panels down closer to the roof. Of course, that's in the "tomorrow" to-do list... and perhaps always will be. 😁

 

[orton]

Ours are currently mounted in a huge frame to be able to tilt the whole deal.

Do not think tilting the panels is very practical. How often will the van be parked at the correct orientation to have the panel tilting worth the effort? How often will your battery SOC require maximum panel output?

 

[Van Gogh]

Hi!
I'm planning on mounting two Solaria PowerXT-400R-PM panels to my 2020 EL Transit. Each is roughly 64 3/4" x 47 1/2". The panel's long sides would span the width of the roof with their ends hanging over the middle of the 1.5" wide roof edge grooves. I would mount them directly to the roof with 1/8" aluminum Z brackets fabricated from two pieces of aluminum angle, similar to how Orton did his: Solar System | Orton Travel Transit

The panels I've seen are elevated an inch or so from the roof, I assume to allow air entry for cooling. But since the roof is crowned and I am mounting across the width, couldn't I mount the center of the panel frame directly to the center of the roof? Only a few inches away the gap would reappear and grow to 2 or 3 inches at the roof sides.

While reading about making a wind fairing for the front, Test of fairings on solar panels to reduce drag I also saw that it may help a lot to make a rear exit fairing as well as side fairings to prevent drag from the underside of the panel. This wouldn't be hard to do but I'm concerned about restricting cooling air flow when I'm parked. I could also but the panels together to save space and prevent drag, but am concerned again about heat dissipation.

Thoughts?

FWIW, I noticed only a very small mpg hit (less than 1) after installing 1,110W of solar using 1515-LS and @Hein brackets. The real MPG hit comes from a lift kit and large tires. Build weight also contributes some.

The main consideration with a center-mounted array is stability. You have to think about the incredible wind-speeds the array faces. I've driven through 40-60mph oncoming gusts while going 80mph. That's not something you want to trust to a few center mount bolts. Full size residential panels panels are like kites, and unless you want to send one into the windshield of a passenger car behind you, possibly killing people and bankrupting your family, I'd advise against any kind of non-standard shortcut install.

Just pay for the 1515-LS + hardware and sleep easy.

Cheers.

 

[orton]

FWIW, I noticed only a very small mpg hit (less than 1) after installing 1,110W of solar using 1515-LS and @Hein brackets. The real MPG hit comes from a lift kit and large tires. Build weight also contributes some.

The main consideration with a center-mounted array is stability. You have to think about the incredible wind-speeds the array faces. I've driven through 40-60mph oncoming gusts while going 80mph. That's not something you want to trust to a few center mount bolts. Full size residential panels panels are like kites, and unless you want to send one into the windshield of a passenger car behind you, possibly killing people and bankrupting your family, I'd advise against any kind of non-standard shortcut install.

Just pay for the 1515-LS + hardware and sleep easy.

Cheers.

My single residential 300 watt panel has four 5/16-18NC bolts through the roof. Not concerned about all the four bolts failing or having the fender washers pull through the roof steel. So far in 5 years I have not experienced a flying panel.

The first Sprinter build had 80/20 cross bars with the ends of the extrusions bolted to the roof rails with four 5/16" bolts. Did not have any issues in 5 years with that panel flying off. Same number of the same size bolts.

Solar System | Orton Travel Transit (ortontransit.info)

 

[Van Gogh]

My single residential 300 watt panel has four 5/16-18NC bolts through the roof. Not concerned about all the four bolts failing or having the fender washers pull through the roof steel. So far in 5 years I have not experienced a flying panel.

The first Sprinter build had 80/20 cross bars with the ends of the extrusions bolted to the roof rails with four 5/16" bolts. Did not have any issues in 5 years with that panel flying off. Same number of the same size bolts.

Solar System | Orton Travel Transit (ortontransit.info)

When you argue "my house hasn't burnt down yet, so no one else's will," it doesn't exactly inspire confidence. That's anecdote, and if we followed that logic, no one would wear seatbelts because some guy named Joe drove for 5 years without one and never got in a wreck. Hardly sensible.

When something doesn't sound right, or someone is looking for a shortcut, I find advising against is the best policy. At very least it's a way to flesh out more details until perhaps a compromise is found that reduces risk.

The impression I got was that he was talking about only mounting the center of two very large 400W panels. Typically modern residential 400W panels are upwards of 68", and many mid-tier panels only have thin aluminum framing with insufficient support. Hopefully he's using a better panel, but that wasn't specified. You may have found a four-point bolting layout for your smaller 300W single panel that was sufficient, but what I heard was an east/west layout with only the middle of the panels bolted.

Maybe there's just a lack of detail here or I misread or some combination of the two, but either way, caution is advised. That setup sounds like a recipe for disaster.

Cheers.

 

[orton]

When you argue "my house hasn't burnt down yet, so no one else's will," it doesn't exactly inspire confidence. That's anecdote, and if we followed that logic, no one would wear seatbelts because some guy named Joe drove for 5 years without one and never got in a wreck. Hardly sensible.

When something doesn't sound right, or someone is looking for a shortcut, I find advising against is the best policy. At very least it's a way to flesh out more details until perhaps a compromise is found that reduces risk.

The impression I got was that he was talking about only mounting the center of two very large 400W panels. Typically modern residential 400W panels are upwards of 68", and many mid-tier panels only have thin aluminum framing with insufficient support. Hopefully he's using a better panel, but that wasn't specified. You may have found a four-point bolting layout for your smaller 300W single panel that was sufficient, but what I heard was an east/west layout with only the middle of the panels bolted.

Maybe there's just a lack of detail here or I misread or some combination of the two, but either way, caution is advised. That setup sounds like a recipe for disaster.

Cheers.

MY LG single panel is 39.37" x 64.57" and is mounted with the long side parallel with the 148" WB. No concerns with using 4 bolts through the roof with reinforcing under the roof. I also selected a panel that has a tubular frame extrusion instead of an angle. The legs are installed on the existing LG leg holes. The legs are about 12 1/2" from the end of the panel with 39 3/8" between the legs on the long sides.

I agree that the OP should give more details about how he plans to install the panels. I would want four legs on each panel. If long way is across van and panels are touching each other, then the center legs could support both panels for a total of 6 legs. It is also important what stiffeners are installed under the roof at bolt locations. Transit roof is too thin to just use a bolt without reinforcing under the roof.

I am old enough that cars did not have seat belts when I started driving. After watching major crashes at sports car races I installed and used seat belts in my cars before cars came with them.. Bought the aircraft seat belt from the WWII surplus store.

 

[gregoryx]

Do not think tilting the panels is very practical. How often will the van be parked at the correct orientation to have the panel tilting worth the effort? How often will your battery SOC require maximum panel output?

Not worth it. That was our conclusion. It was initially in the, "how cool would it be..." category... so we did it. Based on our winter excursions with the Sprinter, we though it might be worth the trouble. But after realizing how much power we can pull from the alternator (~2kW vs ~400W on Sprinter), really don't need them.

The DC air-conditioning unit goes in soon... but since that'll be used more non-winter, don't need tilting much.

 

[Van Gogh]

MY LG single panel is 39.37" x 64.57" and is mounted with the long side parallel with the 148" WB. No concerns with using 4 bolts through the roof with reinforcing under the roof. I also selected a panel that has a tubular frame extrusion instead of an angle. The legs are installed on the existing LG leg holes. The legs are about 12 1/2" from the end of the panel with 39 3/8" between the legs on the long sides.

I agree that the OP should give more details about how he plans to install the panels. I would want four legs on each panel. If long way is across van and panels are touching each other, then the center legs could support both panels for a total of 6 legs. It is also important what stiffeners are installed under the roof at bolt locations. Transit roof is too thin to just use a bolt without reinforcing under the roof.

I am old enough that cars did not have seat belts when I started driving. After watching major crashes at sports car races I installed and used seat belts in my cars before cars came with them.. Bought the aircraft seat belt from the WWII surplus store.

Okay, but again, my response to him was expressing concern about a center-mount only solution. I'm sure you found a way to install your panel, and that's all well and good, but no one should attempt to mount a giant 400W residential panel on an 80mph+ van at just the center. That's dangerous.

It's good you added seat belts after you learned how dangerous it was without them. Advising people to use more than just center-mounts for giant residential panels on an 80mph+ van should be easy after doing some similar research:

https://uk.sports.yahoo.com/news/video-watch-moment-solar-panels-152028660.html

Our solar panel blew off!! - Escape Trailer Owners Community

On the first day of our 2 week trip to South Dakota we hit a few rain squalls with crosswinds. Sometime after filling the gas tank in Trinidad (where we did a walk around check and everything looked

www.escapeforum.org

Cheers.

 

[Van Gogh]

Not worth it. That was our conclusion.

I completely agree. Winter is when you need power the least if you have a webasto and a reasonably sized solar array. It's really summer a/c power consumption and whether or not you're full-time living in the van in a hot and/or humid place.

I've had my minisplit running for 6 weeks nonstop and it's pretty much always powered by the sun. I'm currently in southern Texas on a hot 90F+ day with high 70+ humidity and down here that a/c is a godsend. I'm still net positive and have been stopping solar charging every time it gets up into the 90's, then letting it fall back to 75. I like having the padding in-case cloudy weather shows up, but I could probably oscillate between 50-75 and put less stress on the batteries.

During this trip, I added charge to the batteries using the inverter/charger three times, and all three were just precautionary. It was during very cloudy/rainy periods, and I just wanted the extra peace of mind of being at 95% before heading to my next destination. In all three cases, my next destination was such that it turned out I didn't need the top-up, but it does appear that if I have to park in the shade for some reason (campsite limitation) or if the weather is really cloudy/rainy, that after about 8 days my batteries can be drained down. If the sun comes out for a day or two during those 8 days, that time gets extended.

Since I'm so often net positive, it's tempting to skip the 48V 100A nations alternator kit I've already paid for (they said they'll refund me, but I did lock in 2021 prices which were much lower). We'll see how the summer goes.

I would like to be able to never rely on grid power. The trade-off is those kits are a pretty massive install with a lot of modifications, so there's some failure risk introduced.

I've found myself debating the @orton method (as we all now affectionately refer to it) of adding a 12V inverter to the ccp (or direct to battery) that can then power my larger inverter/charger.

See Orton, I do appreciate your wisdom!

Cheers.

 

[arthurdeernuts]

Thanks for the feedback. Am I OP? I'm not considering a center mount only panel. I am considering using Orton's mounting method. I'd have two panels about the same size as his single panel. I would turn mine 90 and add center mounts. The rear center mount of the front panel might be able to serve also as the front center mount of the back, leaving a small gap between the two panels. Fairings would be added according to hits in the MPG. I'm really surprised VG had a minimal reduction. Maybe adding fairings would make it better than no panels at all, hehe!

Actually, there wouldn't need to be any brackets in the center. Just bolt the panels directly to the roof.

 

[orton]

Okay, but again, my response to him was expressing concern about a center-mount only solution. I'm sure you found a way to install your panel, and that's all well and good, but no one should attempt to mount a giant 400W residential panel on an 80mph+ van at just the center. That's dangerous.

It's good you added seat belts after you learned how dangerous it was without them. Advising people to use more than just center-mounts for giant residential panels on an 80mph+ van should be easy after doing some similar research:

https://uk.sports.yahoo.com/news/video-watch-moment-solar-panels-152028660.html

Our solar panel blew off!! - Escape Trailer Owners Community

On the first day of our 2 week trip to South Dakota we hit a few rain squalls with crosswinds. Sometime after filling the gas tank in Trinidad (where we did a walk around check and everything looked

www.escapeforum.org

Cheers.

I just reread his first post. I believe he was talking about if it was a problem if the center of the panel was touching the roof. I commented that the panel would rub off the paint due to vibration if it was touching the van steel. Do not think he was suggesting that he was only going to put legs at the center of the panel. That would not work.

I fully agree that only using feet at the center would not be advised. Do not think that was his intent. We do not disagree. Only center mounts would not be acceptable.

 

[Mark Haas]

I haven't taken pictures. I have 4 100w panels mounted directly to the roof with the strip magnets from Harbor Freight mounted on outside edges of the panels. Panels have a 1/2 air gap under them. Max velocity of my 2015 350 HD is indicated 95mph. Feels electronically limited, probably not a bad thing. Panels have not moved in (doesn't get out much) 3k miles.