Solar. One 300w panel or 3 x 100w panels?

I'm just in the process of converting my 158wb T1N. I've got a rough idea of the electrical system I want, but I'm looking for some input.

Right now I'm thinking of 2 100AH Battleborn Lithium batteries with 300 watts of panels. I already have both Maxxfans installed with enough space left to either put 3 100w panels or 1 large 300w panel. I'm planning to mount the panels straight to the roof with bolts or self drilling screws and seal them with LAP sealant same as the fans. The large panel is appealing because it would be less holes in the roof and just simpler to install. If I get 3 panels is it possible to bolt the panels to each other along the long sides (turning them into one large panel) and then just have it mounted to the roof around the edges? I'm open to other mounting options, but the van has no sort of roof rails or rack at the moment.

Besides the panels, I'm thinking of the Victron MPPT 100/30 charge controller.. I've heard good things about this brand. Is this sufficient for the panels? Also need a battery monitor, haven't settled on this yet either, probably go Victron here as well.

Thanks!


Oh, I'm also roughly planning the wiring and layout for everything. I'm thinking I'll get duplex wire and run them all inside split loom tubing through the walls and ceiling. I haven't insulated yet, should I try to run wiring through the crossbeams first, or do Thinsulate first, then wiring?

They make wire specifically for solar panels, with the MC4 connectors already attached, I'd use that, and a single solar panel, for simplicity. https://www.amazon.com/slp/solar-panel-wiring/ownycf83ff6r5d9 . Bolting right to the roof is not the greatest idea, as you should leave an air gap to the roof for better cooling (and it also reduces wind induced stress, in theory). That being said, I have a friend who didn't care, his panels are still working "fine" if slightly less efficient than ideal while bolted right to an RV roof. For passing through the roof, use bulkhead fittings or the little plastic box thing that many others are using (ugly ; ) but not often visible). https://www.amazon.com/Weatherproof...anel+bulkhead&qid=1566428274&s=gateway&sr=8-8 No split loom necessary but it wouldn't hurt.

The victron controller you selected is good. So is their battery monitor. So are the Battleborn batteries. This is all the same stuff I've been using for a year now with no issues. I wired after thinsulate, as I want access without removing it, but could be done either way. I did not go through any crossbeams.

One big one, higher Voc too right?

Yes that Victron's fine.

We do both 3x100 watt arrays and 300+ watt single panels. Larger panels really ought to be supported at 3 places along the long sides. With multi-panel arrays shade on one panel appears to reduce overall output less than shade on a portion of a single large panel. But I have not seen anyone measure this behavior.

Take a look at our direct mount towers. They will raise the panel above the roof for better cooling. They have a large foot print that would be great for distributing the load over a larger area. I would suggest using VHB under them along with 2 through bolts. They will be easy to attach to the panels with the hardware we provide. They can also be used with 3 panel arrays. One large panel will simplify the wiring on the roof. Be aware the the voltage output is generally higher with the large panels so controller will need to be capable of handling that.

All the best,
Hein
DIYvan
541 490 5098


https://www.ebay.com/itm/142844825394

Let us know and we would be happy to include VHB tape at no extra charge.

Thanks guys. I should clarify, I don't plan to bolt the panels directly to the roof themselves, but simply using these brackets: https://www.amazon.com/Renogy-Solar...enogy+bracket&qid=1566493725&s=gateway&sr=8-2

Should give me and inch or two air gap. The bigger panel would give me 24v so it would charge better in low light right? Or, I could wire the 3 12v panels to output 36v? Is it possible to wire 2 panels in series and the other parallel, or with an odd number of panels do they all need to be wired the same?


Also, could I bolt the three panels together on the sides and mount it as one large panel?

I mounted 400w on my 140WB sprinter and what I did was buy 3 pieces (I think 2 would work for your setup, had to get the 3rd to fit the 4th panel) of 2" x 2" x 8' 1/8" thick aluminum L track. I installed 2 riv nuts in the shorter edge of each panel, then drilled holes toward the very top of my L track. Then I mounted the L track to my roof using 3M 5952 VHB tape. Then I mounted the panels to this. Sorry if it is hard to understand, here is a short little clip I made that may clarify: https://photos.app.goo.gl/6s8kz72S9WLKSrrg7 (I have a longer YouTube video but did not want to seem like I was trying to promote my channel, let me know if you want the link)

gth853s said:

Thanks guys. I should clarify, I don't plan to bolt the panels directly to the roof themselves, but simply using these brackets: https://www.amazon.com/Renogy-Solar...enogy+bracket&qid=1566493725&s=gateway&sr=8-2

Should give me and inch or two air gap. The bigger panel would give me 24v so it would charge better in low light right? Or, I could wire the 3 12v panels to output 36v? Is it possible to wire 2 panels in series and the other parallel, or with an odd number of panels do they all need to be wired the same?


Also, could I bolt the three panels together on the sides and mount it as one large panel?

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The Renogy brackets are very thin with a tight bend radius so prone to fatigue cracking over time. Our brackets are much thicker and have a generous bend radius to prevent stressing the aluminum. If you want the Renogy style brackets then suggest you use these stainless ones instead: https://temcoindustrial.com/shop/solar-hardware-tools/solar-mounting-brackets

If you do decide the to bolt panels together then you'll want to reinforce the connection with some aluminum angle. see image below.

All the best,
Hein
DIYvan
541 490 5098

I went with one 300W 24V panel and used the Renogy Z-brackets. I bought two sets of the brackets so there are 4 Z-brackets per side and attached them to the roof with VHB tape. I was a bit concerned with heat (black van) but I've never seen my state of charge below 92% at any time of year. I have an independent solar-electric system, no B-B charger or isolator, and don't foresee a need to connect to the van electrical system for my use.

Perhaps consider to look at 150 watt RV size panels and see if you can get 3 of them on top.

They are typically ~ 28 x 56 or similar.

They might hang slightly over but 450 watts of solar is extremely helpful in running things vs even 300.

JoeyB said:

I mounted 400w on my 140WB sprinter and what I did was buy 3 pieces (I think 2 would work for your setup, had to get the 3rd to fit the 4th panel) of 2" x 2" x 8' 1/8" thick aluminum L track. I installed 2 riv nuts in the shorter edge of each panel, then drilled holes toward the very top of my L track. Then I mounted the L track to my roof using 3M 5952 VHB tape. Then I mounted the panels to this. Sorry if it is hard to understand, here is a short little clip I made that may clarify: https://photos.app.goo.gl/6s8kz72S9WLKSrrg7 (I have a longer YouTube video but did not want to seem like I was trying to promote my channel, let me know if you want the link)

Click to expand...

Just for the sake of clarity for those reading the thread: That is not L track. That is extruded aluminum angle. This is L track:

One panel has worked fine on both the Sprinter build and the Transit build. Simpler wiring and an outside rack is not required. Think inside the box and put rack under the roof. My experience is I am either in full sun or full shade so not much benefit to multiple panels. I used four feet and used the existing panel holes so feet are not at the end of the panel. No issues.

One way to install a single panel:

https://www.ortontransit.info/solar-system

I have one 360 watt panel on mine, it gets my 100Ah Battleborn to float everyday even when cloudy or rainy, running an Engel fridge, lights, pump, and Maxair fan.

monoloco said:

I have one 360 watt panel on mine, it gets my 100Ah Battleborn to float everyday even when cloudy or rainy, running an Engel fridge, lights, pump, and Maxair fan.

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Rainy? What sort of output have you recorded for this event, and time of year, location, rainfall type/amount?

I'm just an old guy.

Do you keep all your eggs in one basket?

I won't 'should' you.

https://en.wikipedia.org/wiki/Redundancy
Click on Redundancy (engineering).

You could call Boeing about that 737 max problem.
Have a chat with some Gen-Xers there.

Here's a little more on common sense which is not convenience.

https://en.wikipedia.org/wiki/Common_sense

The outcome may ultimately hinge on your going to Bolivia(or not).

Or the future.

Or the desire to think.

bill in tomahawk

billintomahawk said:

I'm just an old guy.
Do you keep all your eggs in one basket?
I won't 'should' you.
https://en.wikipedia.org/wiki/Redundancy_(engineering)
You could call Boeing about that 737 max problem.

bill in tomahawk

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i won't too. i like your thinking.
i will vote for 3 solar panels to in case 1 get faulty

sassyinpink said:

i won't too. i like your thinking.
i will vote for 3 solar panels to in case 1 get faulty

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If you go with three panels in order to increase reliability (by having two panels that continue working even if one of the three fails) be sure that your wiring configuration doesn't cause the failing/failed panel to cause a problem anyway.

The interesting thing about trying to increase system reliability through redundant components is that the increased number of components actually increases the probability of a failure in at least one of the redundant components. Making sure that a failure in one of the redundant components doesn't cause a system failure is important and (oddly enough) sometimes overlooked.

OrioN said:

Rainy? What sort of output have you recorded for this event, and time of year, location, rainfall type/amount?

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Just got back from the Oregon coast where we had one day of rain and one day that was overcast all day, both days the battery got to float. I'm pretty sure that I would need another charging source if I planned to spend the winter at the Oregon coast, but since I live in Baja Sur, I think my one panel will be sufficient for our needs.

sassyinpink said:

i won't too. i like your thinking.
i will vote for 3 solar panels to in case 1 get faulty

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I lived off the grid for 25 years and never had a solar panel go bad. A quality solar panel is a pretty reliable thing.

You should install what fits best. Have a look at some AM Solar videos on YouTube. They do not screw their panels down at all. They use their custom mount and stick it to the roof with a special 3m tape and then cover it all with sealant. Which I would have done mine this way.

Getting to float should, but does not necessarily mean the bank got to 100% Full.

Ideal for multiple panels is a SC for each, not just redundancy but optimal shade handling.

But one quality panel is best IMO.

If your survival requires electricity, you always have your alt.