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Discussion Starter · #1 ·
Hi - I've got a LWB High Roof & am plotting out my roof layout. Tough to find exact measurements but from what I can tell, the roof is about 121" x 54".

I've ordered two Maxxairs and Hein's standard and forward roof adapter. I'm guessing the forward adapter will add a few inches to the real estate, but not much.

I'll be running solar into a goal zero 6000x. I'd like to try series wiring to start, which leads me to these two panels (Renogy 200 watt - 63.8" x 25.9") as the best bet. If I do my own battery build down the line or switch to parallel, I believe I could fit this as well (Renogy 175 watt 52.2" x 26.3"), if I offset my rear roof fan.

Assuming my math is accurate, we're on to how to mount these panels? I've also seen a lot of talk about using the weatherguard roof rails. This is interesting to me because I would probably like to attach a make shift awning or potentially other gadgets at some point. I'm not against using dedicated panel mounts or an alternative rail/rack system though.

Any suggestions or at least confirmation that this checks out before I start ordering more pieces would be very appreciated.

And re: goal zero - I know that's a ton of amp hours, but my calculations are that I will burn through about 300 hours on a good day. The only other generators I found are too small or on backorder through summer. So I'll have juice to spare and be able to weather some cloudy days stress-free.

Thanks
 

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Skip the Goal Zero and install a proper charge controller and inverter. While their cost/Wh after factoring in the electronics is okay on the smaller units, it does not scale appropriately. You'll also want faster alternator charging with that much capacity.
 

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Discussion Starter · #3 ·
Skip the Goal Zero and install a proper charge controller and inverter. While their cost/Wh after factoring in the electronics is okay on the smaller units, it does not scale appropriately. You'll also want faster alternator charging with that much capacity.
I may revisit this, but I'm already undertaking a lot of new disciplines building this thing and I decided to go generator vs home-made... At least for the first iteration

Mostly curious about the roof layout. I do appreciate the feedback there, though.
 

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You might consider a single high voltage solar panel with a MPPT solar controller. Can be installed without a roof rack which would leave the Transit tapped roof holes available for other uses.

I have been very satisfied with my single panel installation:

Solar System | Orton Travel Transit (ortontransit.info)
 

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2021 AWD 148" HR 3.5L EcoBoost Avalanche Grey
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Sounds like your goals are: 2 fans plus as much solar as possible. This is a common set of goals and I have the same goals. I'm also planning my roof layout for a summer build. I think it's pretty tough to plan exactly, you'll just need to get the parts and see what you can make work.

Based on this post Dual Roof Vents I think you get 44" between the fans. Remember that the cutout is 14"x14" but the actual fan is much larger.

I'm using a AVC RIG roof rack (which has specific dimensions listed for usable width and length) and a TinyWatts solar panel crosswise. I am pretty sure I can make that work based on the dimensions of the panel they gave me (they've updated their website since with different panels). If I can't fit it, I will probably install the front fan backwards, which I think should be ok since the roof rack has a front fairing. I saw somebody post that they did this on a Sprinter and it didn't break after several years. Main concern would be wearing out the fan lift mechanism early.
 

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2021 AWD 148" HR 3.5L EcoBoost Avalanche Grey
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Also I think your dimensions are pretty far off. As a benchmark note that usable part of the AVC RIG roof rack is 112"x60.25". You can probably get some more length by hanging over the front or back but not if you have two fans. Remember that the fans have to be installed in pretty specific locations in the NS dimension due to the ribs.
 

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Do you need two roof fans? I have a 148" not extended with one Maxxair fan. In my climate I almost never power the fan. I do have a 4" square hole in the floor to provide a source of cooler air that goes out a unpowered open Maxxair.

Considering removing the Maxxair and replacing it with a lower power fan to eliminate the very non-stealth Maxxair housing.
 

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2021 AWD 148" HR 3.5L EcoBoost Avalanche Grey
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Do you need two roof fans? I have a 148" not extended with one Maxxair fan. In my climate I almost never power the fan. I do have a 4" square hole in the floor to provide a source of cooler air that goes out a unpowered open Maxxair.

Considering removing the Maxxair and replacing it with a lower power fan to eliminate the very non-stealth Maxxair housing.
Ah yes, the eternal debate. Probably the top debated question after insulation. I have absolutely had this debate with myself and there very well may be a fan for sale come July. My current thinking is:

1. People love to point out the CFM of the fan and how many times it turns over the air in the van per hour. That's great if you are operating at the manufacturer claimed CFM. But for that the area of the holes that feed the fan must be roughly equal to the area covered by the fan in order for the fan to be fully effective. Area grows quadratically, so a 4" square hole has 16 sq in of area, vs the 12" diameter of the MaxxFan giving you 113 sq in of area. That's a huge difference. In order to make up 113" with small holes you need a lot of them.

2. Floor vents come with road dirt and debris concerns that must be mitigated. Not saying it's not possible but it's more stuff to do.

3. I definitely want to vent directly over the cooking area for smell and moisture reasons.

4. I thought about a bunk window (Arctic Tern) on the driver's side of my EW bed in the back, but if I use this and a fan in front to vent when I'm chasing snow, this will result in cold air being drawn directly over my bed from outside, and the air circulation will be the wrong direction to get heat from my Espar which will be more central driver's side low down. A reversible fan over the bed means I can gently pull air out using it, which will circulate heat towards the back instead of away from the back. Bonus is that in the summer I can make it blow straight down on me, a similar experience to in my current camper (a teardrop trailer).

5. I plan to vent my toilet and my Espar down low, so a floor vent is more likely to pick up less desirable air.

Of course, there are disadvantages of two fans, including roof layout puzzles, more holes in the roof of your van, only pulling air from the top of the van rather than cool air from below, maybe cost depending on what you do (though a fan is cheaper than most of the windows I've seen), and probably other things I'm forgetting.
 

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Ah yes, the eternal debate. :)
1. You have to consider if the fan CFM might be overkill for the small van volume. I think it is. Maybe a fan that is closer to the area of the 4" square hole would be more appropriate for a small conversion? For my conversion and climate my single Maxxair provides far more airflow than needed. I may remove it and replace it with a much lower CFM fan. Currently in my climate I almost never turn it on. I do open the floor hole and the Maxxair.

2. I located the 4" square hole just in front of the driver side rear wheel. Have not had an issue with road dirt. Vent is open 95% of the time. I would close it on dirt roads and I do close it on cold nights to retain heat.

3. My indoor cooking area is located at the sliding door. Found the cooking steam and smells go up and out the open slider door.

4. My Maxxair is located over the bed platform. Warm air rises so air flow is up out of the floor hole and out the open Maxxair. I think that is better than air flow in one Maxxair and then just under the roof to the second Maxxair. Do not believe both 14" roof openings need to be powered (if you must have two).

5. I do not have a Espar or a toilet with a vent. Stay warm with a 12 volt rear seat heating pad under the zero degree sleeping bag. Let van interior get cold at night. Portapotti does not have a vent.

I have fixed window in the slider door and a fixed window in each rear door .
 

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2021 AWD 148" HR 3.5L EcoBoost Avalanche Grey
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I thought we were talking about my van, not yours. I'm glad you're happy with one fan. I am explaining why I think two is right for me. You said "Do you need two fans?" Explaining how your van doesn't need two fans isn't really relevant. Everyone's build is different and everyone makes trade offs for this or that depending on what's important to them.

1. You have to consider if the fan CFM might be overkill for the small van volume. I think it is. Maybe a fan that is closer to the area of the 4" square hole would be more appropriate for a small conversion? For my conversion and climate my single Maxxair provides far more airflow than needed. I may remove it and replace it with a much lower CFM fan. Currently in my climate I almost never turn it on. I do open the floor hole and the Maxxair.
That is certainly a good point. I'm glad you live/travel in a climate where you don't need more airflow. I've camped in my teardrop (10% volume of the Transit) in the desert and need the MaxxFan Deluxe on full blast and all windows open to keep it comfortable. This is a big concern for me since I have a dog who will stay in the van sometimes while I'm off hiking or whatever. Being able to actually change over the air several times per hour is important to me.

4. Do not believe both 14" roof openings need to be powered (if you must have two).
This is probably true. I like that they will match and that they can both be open in the rain. Can't have that with many of the other options without some ridiculous cover.

I think we've hijacked this thread enough though. Let's let the OP think about roof layouts and get back to us :)
 

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I thought we were talking about my van, not yours.

Being able to actually change over the air several times per hour is important to me.
Just trying to help. No need to get aggressive.

I thought all 148" WB high roof Transits were similar in size. Yours and mine.

A van interior is roughly 6' x 6' x 18' or about 648 cubic feet. Read that a single Maxxair 7500 has 900 cfm rating. 648/900 = .72 minutes. So less than 1 minute to change the air if the inlet and exhaust were at the ends of the box. In your case with two fans in the roof the air flow would never change the whole van volume. But the air at the ceiling between the two fans would certainly be changed many times.

Maybe you will need to build a platform for the dog so it is up high in the van between the two fans?
 

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2015 3.5L EB 148 Highroof Extended
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I have 6 x 100W Compact Renogy panels on my van. They fit in two rows on either side of the fan in the front. In the rear I have a Dometic skylight which is a bit wider than a maxxairfan. This means I had to shift the panels toward the front, and overhand the curved portion of the roof a bit. The same configuration would work just fine with two maxxair fans. There's also a bit of roof leftover in the middle for my maxtrax

152095


152096


The rack DIY using extruded aluminum.
DIY Van Roof Rack — STOKE LOAF VAN
 

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2021 AWD 148" HR 3.5L EcoBoost Avalanche Grey
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Just trying to help. No need to get aggressive.
Too bad there's no font for tone. Didn't intend to be aggressive. I appreciate your help and thoughts!

A van interior is roughly 6' x 6' x 18' or about 648 cubic feet. Read that a single Maxxair 7500 has 900 cfm rating. 648/900 = .72 minutes. So less than 1 minute to change the air if the inlet and exhaust were at the ends of the box. In your case with two fans in the roof the air flow would never change the whole van volume. But the air at the ceiling between the two fans would certainly be changed many times.
Think that's a little extreme. Pretty sure air molecules one inch below the ceiling (not just the ones at the ceiling) will also be exchanged 😉 In all seriousness though absolutely it's true that air exchange would better and faster if it has directional flow rather than turbulence. But turbulence also moves air. The air by the floor won't be circulated as often, but it will move, especially with two holes the same size and thus full CFM. You know how powerful the fan is when you have it on full blast. It pushes air hard enough to create turbulence way lower than just right at the ceiling.

New idea: just put one of the fans in the floor! 😝
 

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Too bad there's no font for tone. Didn't intend to be aggressive. I appreciate your help and thoughts!



Think that's a little extreme. Pretty sure air molecules one inch below the ceiling (not just the ones at the ceiling) will also be exchanged 😉 In all seriousness though absolutely it's true that air exchange would better and faster if it has directional flow rather than turbulence. But turbulence also moves air. The air by the floor won't be circulated as often, but it will move, especially with two holes the same size and thus full CFM. You know how powerful the fan is when you have it on full blast. It pushes air hard enough to create turbulence way lower than just right at the ceiling.

New idea: just put one of the fans in the floor! 😝
If you are installing an Esperbacher heater you will have a fan in the floor. As you probably know, the Espar has a fan function that moves air nicely. I've found that turning on the Espar fan on low and running the maxfan really ventilates quite well. My intake is below the passenger seat and my composting toilet is on the driver side and haven't noticed and smell operating in this configuration.
Good luck on your build.
 

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If you are installing an Esperbacher heater you will have a fan in the floor. As you probably know, the Espar has a fan function that moves air nicely.
I need to look at the schematics of the Espar again, but I thought that the holes in the floor with intake and exhaust are not actually transferring air into the van. I thought that externally circulated air is used for combustion--which is isolated and separate--and that the fan pulls from the butt of the Espar through a heat exchanger to the front, and this is the air that is warmed. I thought this is how the Espar avoids adding the moisture that is a side effect of the combustion process to the van. It’s been a while since I researched that though. Am I missing something?


Edit: I'm not missing something. Unless your heater is mounted outside the van, it's only circulating air within the van.


Edit 2: It's true that the fan will still circulate air, it's just not exchanged with air outside so I don't think it counts as a "vent."
 

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Well... back to the originally scheduled program...

@DRIFSONIX , not sure what year your rig is, but the 2020+ units have a 250A alternator and some have two. That can make up a big difference in solar needs. ~500W didn't seem enough on our old rig - mostly in winter. But we know now that we didn't need to do 800W on the new rig since the alternator will put in over 1kW while idling. If we had to do over, we'd probably go down to 600W - maybe even add another fan. ;)

I agree that the measurements are not quite what we've experienced on the van. HR-Ext, we're seeing over 11' (~126+) from behind the shark-fin antenna to the very rear corners. Of course the very rear are harder spots to use since there's no built-in bolt-holes there, so consider that. And we've got a touch over 60" wide with panels and rails and we're not sticking over the sides; but we're pretty close to edge-to-edge. Running these solar panels (200W) - about 59" plus 30mm aluminum framed around them - so officially, that's about 61.5" or so. So those panels will be overhanging a bit - and that's assuming you use under-mount brackets. Which means... if you want to attach an awning... either the panels are rather high up off the roof OR you've actually got another couple inches around them for awning mount (unless you do the van-wall mount - which is an option for awnings).

152116


I know you're going with the Goal Zero; but I'll also chime in to suggest considering alternatives. The max input on it is 600W. That means your max solar is 600W and your max alternator input is 600W and your max AC input is 600W. Not a big deal, I suppose... but that means that draining 6kWh would take 10 hours to re-charge. Unless I'm missing something... that's terrible a bummer.

As always, you do you; but with modern lithium batteries being willing to gladly accept what's called "one-half-C" input, 6kW of battery should take up to 3kW charge rate. Not saying you'd need that... but we'll hit our batteries with 1.5kW or more from the alternator if we've drained them a bunch (in winter, typically) and can even aggregate that will solar and the batteries will accept the input. Or charge from outside AC and get 2.4kW or whatever the outlet will do. By comparison, 1.5kW from the alternator would charge from empty to full in four hours. Bummer not to be able to do that - especially for that money. But I certainly appreciate the trepidation of /one more thing/ to deal with. 😏

Back to the solar: might make sense to consider 3 x 175W if you want two fans. They'd fit /inside/ the roof-rack rails and you'd have room for awnings or whatever. And... if you get the alternator charging working with a non-Goal-Zero setup, you're in way better shape, power-wise. And spent less.
 

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A few thoughts.

RE the GZ: the GZ 6000X can take 750W of solar charge, and similarly the link module can push 750W from the alternator. With two fans, I think getting 750W of solar on the roof is going to be impressive. I have a GZ3000 in my van and am thrilled with it. There are threads about that decision I am sure you have read. But I continue to believe that the GZ is an amazing deal, especially if you are patient enough to wait for one of REI's 20% off coupons.

RE the roof vents: this is one I wrestled with a lot on my build as well. I ended up going with a completely different approach and installed distributed duct work. After a year of use (-20ºF snowboard missions, and +102º sleeping temps in Death Valley) I am thrilled with the system. Mount a fan in the floor? I think two fans is unnecessary. Two roof opening, could definitely make sense to me, but two active fans seems like extreme overkill when considering the size of the space. It definitely works, and that is awesome, but a system with a single fan and a roof vent conveniently placed under the solar panels would get you nearly the same effective solution.

RE: the solar mounting: I did not opt for roof mounted solar, so I don't have any specific recommendations, but I would go with a rack mounted system if I were to add mounted panels. The rack systems allow greater flexibility and stability of the system. Mount the rack tot he factory mounting points, then build the system based ont he rack. It avoids custom mounting issues, and will likely make service down the road easier.
 

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I am currently placing the solar panels in a Front Runner Slimline II rack. (58”x 108”) With a Maxxair fan located near the rear center. 4 Renogy compact 100w panels will be mounted 2 in front and 1 ea side of the fan. Tight fit but it works and the rack will hide most of the panels. Painted the panel trim black to help camouflage.
152142


With a little adjusting of the rail layout, it allows for about 2’ of “deck” behind the panels that will be utilized later. I’ll post pics after completed this week of all goes well.
 

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Discussion Starter · #20 ·
I went away for a day and ya'll had a party in here 🥳

Funny, cause it was a slow start and I was thinking "dammit, I'm on my own here"

Anyway, my thoughts...

You might consider a single high voltage solar panel with a MPPT solar controller. Can be installed without a roof rack which would leave the Transit tapped roof holes available for other uses.

I have been very satisfied with my single panel installation:

Solar System | Orton Travel Transit (ortontransit.info)
I appreciate this and something to consider for sure... currently I'm in "Drill as few holes in the roof as possible" mode... ironic given I'm going for two fans, but I'm trying to stick with it.

Also I think your dimensions are pretty far off. As a benchmark note that usable part of the AVC RIG roof rack is 112"x60.25". You can probably get some more length by hanging over the front or back but not if you have two fans. Remember that the fans have to be installed in pretty specific locations in the NS dimension due to the ribs.
Does anyone know the actual dimensions? I will be able to climb up on top in a few days, but haven't had a chance yet. Did some transposition from interior measurements and combing threads. This would help me visualize quite a bit.

Do you need two roof fans? I have a 148" not extended with one Maxxair fan. In my climate I almost never power the fan. I do have a 4" square hole in the floor to provide a source of cooler air that goes out a unpowered open Maxxair.

Considering removing the Maxxair and replacing it with a lower power fan to eliminate the very non-stealth Maxxair housing.
I looked into some options, but it seemed like everyone said the maxxair was leaps and bounds beyond competitors, mostly for that rain cover. I ordered an automatic and a manual fan for exhaust and intake duty, respectively. I will keep considering options until they're attached though, so may have one for sale if I go another route.

Similar to my minimal roof hole theory, I'm hesitant to cut the floor. Also, I think I'll need powered intake? There'll be groups of people inside for extended periods, so I'm really trying to keep the air fresh and cool as possible.

I have 6 x 100W Compact Renogy panels on my van. They fit in two rows on either side of the fan in the front. In the rear I have a Dometic skylight which is a bit wider than a maxxairfan. This means I had to shift the panels toward the front, and overhand the curved portion of the roof a bit.

The rack DIY using extruded aluminum.
DIY Van Roof Rack — STOKE LOAF VAN
Appreciate this option and the roof rack link. If I go 100w panels, I will likely have to ditch the goal zero, as it tops out at 50volts. That's what's largely driven me to the 2 x 200 watt setup. I'm trying to go series wiring if possible. Lots more options parallel, but I've been convinced that series is the best approach. Thought process being that higher voltage coming in will allow charging earlier/later in the day and extend the total hours that the panels are useful. Shading issues can be avoided in many cases.

Well... back to the originally scheduled program...

@DRIFSONIX , not sure what year your rig is, but the 2020+ units have a 250A alternator and some have two. That can make up a big difference in solar needs. ~500W didn't seem enough on our old rig - mostly in winter. But we know now that we didn't need to do 800W on the new rig since the alternator will put in over 1kW while idling. If we had to do over, we'd probably go down to 600W - maybe even add another fan. ;)

I agree that the measurements are not quite what we've experienced on the van. HR-Ext, we're seeing over 11' (~126+) from behind the shark-fin antenna to the very rear corners. Of course the very rear are harder spots to use since there's no built-in bolt-holes there, so consider that. And we've got a touch over 60" wide with panels and rails and we're not sticking over the sides; but we're pretty close to edge-to-edge. Running these solar panels (200W) - about 59" plus 30mm aluminum framed around them - so officially, that's about 61.5" or so. So those panels will be overhanging a bit - and that's assuming you use under-mount brackets. Which means... if you want to attach an awning... either the panels are rather high up off the roof OR you've actually got another couple inches around them for awning mount (unless you do the van-wall mount - which is an option for awnings).

View attachment 152116

I know you're going with the Goal Zero; but I'll also chime in to suggest considering alternatives. The max input on it is 600W. That means your max solar is 600W and your max alternator input is 600W and your max AC input is 600W. Not a big deal, I suppose... but that means that draining 6kWh would take 10 hours to re-charge. Unless I'm missing something... that's terrible a bummer.

As always, you do you; but with modern lithium batteries being willing to gladly accept what's called "one-half-C" input, 6kW of battery should take up to 3kW charge rate. Not saying you'd need that... but we'll hit our batteries with 1.5kW or more from the alternator if we've drained them a bunch (in winter, typically) and can even aggregate that will solar and the batteries will accept the input. Or charge from outside AC and get 2.4kW or whatever the outlet will do. By comparison, 1.5kW from the alternator would charge from empty to full in four hours. Bummer not to be able to do that - especially for that money. But I certainly appreciate the trepidation of /one more thing/ to deal with. 😏

Back to the solar: might make sense to consider 3 x 175W if you want two fans. They'd fit /inside/ the roof-rack rails and you'd have room for awnings or whatever. And... if you get the alternator charging working with a non-Goal-Zero setup, you're in way better shape, power-wise. And spent less.
Thank you for getting us back on track 😂 I will try to be more present going forward so I don't have to drop such a massive multi-quote again.

I have a 2019. Oldest I could find after months of searching lol. That's a good point about charge times. I think on a BIG day, I might use 350 amp hours of battery. My thought was that I would have a few days supply with this set-up, but yeah getting it done faster is always nice.

So if I go non-goal zero, I would probably just get 3x100 batteries & from what I can see that setup is approaching the goalzero price tag pretty quickly. Believe me, I was all-in on building my own system at first

For context, here's my usage plans:

The nice thing about the GZ there is it's portable, too. So I could really be mobile with my setup. Though I assume it's not something I'd want to move much.

A few thoughts.

RE the GZ: the GZ 6000X can take 750W of solar charge, and similarly the link module can push 750W from the alternator. With two fans, I think getting 750W of solar on the roof is going to be impressive. I have a GZ3000 in my van and am thrilled with it. There are threads about that decision I am sure you have read. But I continue to believe that the GZ is an amazing deal, especially if you are patient enough to wait for one of REI's 20% off coupons.

RE the roof vents: this is one I wrestled with a lot on my build as well. I ended up going with a completely different approach and installed distributed duct work. After a year of use (-20ºF snowboard missions, and +102º sleeping temps in Death Valley) I am thrilled with the system. Mount a fan in the floor? I think two fans is unnecessary. Two roof opening, could definitely make sense to me, but two active fans seems like extreme overkill when considering the size of the space. It definitely works, and that is awesome, but a system with a single fan and a roof vent conveniently placed under the solar panels would get you nearly the same effective solution.

RE: the solar mounting: I did not opt for roof mounted solar, so I don't have any specific recommendations, but I would go with a rack mounted system if I were to add mounted panels. The rack systems allow greater flexibility and stability of the system. Mount the rack tot he factory mounting points, then build the system based ont he rack. It avoids custom mounting issues, and will likely make service down the road easier.
Good to hear from a happy GZ customer. Yes, I read so many threads. I did find some issues, but it seemed like the company is down to work with folks to resolve them. REI doesn't have the big dog yet, unfortunately but I'm refreshing regularly.

Vent under the solar panels is an interesting idea. I guess that would take care of the rain issue. Plus save space. I wonder about closing/covering it from the outside though. That's a tight area and I'll bet it would be tough to seal. Also depends if a passive intake is enough for my uses... probably will be up to 4-6 people in it at a time some days.

Ok... Think I answered everything... Thanks guys, really appreciate this.
 
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