Determining roof space before purchasing panels.

[Kenny P]

Hey there. I have a chevy Astro cargo van. It's smaller than the ford econolines and the chevy express/savannah. My van is insulated and the interior is finished.
I'm feeling pretty bummed because I installed a fantastic fan on the roof, and now, 6 months later, I want solar.
I should have done the solar and the vent in the same project because I know it will get in the way of installing panels.
I want to go as big as possible as far as wattage goes.
After a lot of reading online and through the threads on this site, I've determined that I want about 500 to 600 watts of solar.
So with my limited roof space, I was wondering if I could get two 300 watt panels? The problem Im running into so far is that most 300 watt panels I see are too large.
Does anyone know of any smaller 300 watt panels?
Any tips on how I should approach this?
I might have to pull that vent and have my friend weld a piece of metal over the opening- the problem with this is that I've heard it's extremely hard to weld on van roofs since the metal is so thin and theres nothing to work with.
Another option would be to get a roof rack, but that vent will most likely still be in the way.
Anyway, any help/guidance would be appreciated.

 

[John61CT]

Yes, the fan and solar, everything on top should be planned together.

Watts output per square area is only marginally improved by more efficient cells.

You can find smaller sized, lower watt panels to arrange around the fan.

But I think to get 500+ watt, you'll need to move the fan, or consider portable panels.

The folding suitcase style takes up a fair amount of stacking space and they're heavy.

These may be better? https://www.amazon.com/ALLPOWERS-Foldable-Technology-Smartphone-Notebooks/dp/B01M5DCPKD

I'm thinking about semi-flex panels mounted on stiff sheets, stacked under a roof rack, pulled out and deployed around the campsite.

 

[Optimistic Paranoid]

I would get a pair of ladder racks like the ones shown, and I would modify them by adding second crossbars - could be metal, could be wood, maybe - close to the very top of the uprights.  Looks to me like that would be high enough to clear the fantastic fan.  You could then run a couple of two by fours lengthwise between the racks, spaced to match the mounting points on your panels.  The panels would shade your roof, keeping you cooler, and you could probably even leave the vent open for ventilation in the rain, with the panels protecting them.

 

[jimindenver]

Bummer thing about mini vans, not much room in side or on top. The flex panels would be the lightest thing to move and store, that's for sure. You could always get a few 300+ watts, place them on the side hinged at the top and flip them up once you park like awnings.

 

[John61CT]

The flex panels would be the lightest thing to move and store, that's for sure. You could always get a few 300+ watts, place them on the side hinged at the top and flip them up once you park like awnings.

That's got merit, biggest puzzle for me is the sheet material to fix the semi-flex to.

It can't bend while in use at all.

Can't be too heavy.

Maybe coroplast-style but more rigid like polycarbonate sheets used for greenhouses.

Bond two sheets with the channels at 90°.

Maybe bond screening to it for extra tensile strength, like the mystery13 process with foam.

 

[MrNoodly]

I would get a pair of ladder racks like the ones shown, and I would modify them by adding second crossbars...etc.

Yes. That's doable. It's what Bob Wells did when he had his converted cargo trailer. There just needs to be enough height so the vent opens enough for the fan to trigger on. The down side is that it's more stuff up in the airflow, so it could affect fuel mileage a little.

I've also seen where people have built racks for their solar panels over all the stuff on top of their RV.

 

[Kenny P]

Well I finlly got some time today to take measurements of my roof. I guess that's the first step in this whole long process.
Now my next mission is to check online and see what size most panels are and how many watts they are.
I'm going to start by looking at the 100watt panels. Determine size, and see how many I could fit around my fan.. then I'll move up to 150watt, 200 watt.

 

[abnorm]

I'm planning on using these rather large Suniva panels with output about 275 watts.......... are about 40" x 66"

doug

 

[MrNoodly]

There are people who mount their panels on the side of their van/trailer/RV.

 

[Kenny P]

So far I found out that any panel over 100 watts are too big to fit more than one on top of my van. But I've determined that I can fit 4 100 watt panels up there since they are much smaller. It'll be a tight squeeze with 4 and I definitely need to look into the mounting brackets because they will probably end up extending out past the panel.


Does anyone know of a panel over 100 watts that has smaller dimensions?

 

[CautionToTheWind]

Would two up top and two portable be too complicated? Titled panels have a greater gain from the sun.

Check out Renogy Eclipse for performance (plus a slimmer profile). There are a few recent threads (using search function).

Here is a 150 watt 39x39 for your reference. May not work however wanted to throw it out there. https://www.renogy.com/renogy-150-watt-12-volt-monocrystalline-solar-panel/#tab_prd-specs

 

[caretaker]

i believe its kyocera that makes 185w12v. i know 2 will easily fit on a chevy express van, as far as your top I'm not sure, i think the dimensions are 18"x 58",,,i think.

 

[John61CT]

As I said, as long as the cells are efficient (e.g. Sunpower 22-25%) the square inches per 100W is pretty constant. Some are shaped long and thin, some more square is all.

Some Chinese makers will do custom layouts.

30 W or 50 W etc may give you more total. Or use the folding portable ones as well as fixed.

As long as they all put out similar voltage specs, you can mix different wattages into a single controller.

 

[Kenny P]

@CautionToTheWind
I'm trying to avoid portable. I want to be able to do some urban camping without drawing attention.

@John61 CT
You were right! Didn't even think about it, but I could fit 9 Lux 50 Watt on top for 450 watts total.
Or 4 Renogy 100 watt panels for a total of 400 watts.
Only problem here is the 50 watt panels cost about the same as the 100 watt panels, so it'd cost twice as much.
I think I'll just have to settle for 400 watts total.

I'd really like to be able to keep my van as stealthy as possible, so I'm looking into getting the thin solar panels.
Are the thin/flexible panels worse than the metal framed ones?

 

[John61CT]

Yes the semi-flex are pricier and don't last quite as long, especially on a van roof.

But you can dicker with the 50W sellers on eBay, I just got one for $60 delivered from Shenzhen.

I see the same panel sold from the Philippines, Thailand and Malaysia.

But this seems to be the mfg direct, they said they can do custom layouts for not much more.

ebay seller name: bzbrlz_sale

​"Liu Bin"<[email protected]>

Shenzhen Xun Long Optoelectronics Technology Co, Ltd