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Roof Configuration For Solar Panels

3043 Views 103 Replies 28 Participants Last post by  CanaDave
I just bought my Promaster, 136, 2500, HR. Trying to figure out how to 'arrange' solar panels on the roof.
Definitely adding a Maxxair to the back of the van, centered, I think. I am looking at after market roof racks, I think that would be a lot easier. But, pretty comfortable with Renogy solar panels. I get the 175's I would need at least 2, three would go off the side of the van in a straight line, but provide more power than I would probably need.They are 52.3x26.4. If I go with 100's they are are 41.8 x 20.9 .
With a MaxxAir, Fridge, lights and kitchen, I need 300w on the roof to be close, 400w would be plenty. Trying not to scrimp as this is my first experience and I don't want to run out of juice and prefer to not pull off the vehicle battery unless I am using the 12v for 'emergencies'. Three 175's would be over by about an inch if I lined them up straight across. Four 100's would be the same problem. Not sure how that affects the stealth aspect, but I would like to keep the stealth aspect available if I need to sleep on a public street.
Thoughts on how to arrange to panels? I think putting less holes in the roof by using a rack that clamps to the feet is a good idea but am open to ideas on not only racks but install thoughts.
Thanks
Andy
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I just bought my Promaster, 136, 2500, HR. Trying to figure out how to 'arrange' solar panels on the roof.
Definitely adding a Maxxair to the back of the van, centered, I think. I am looking at after market roof racks, I think that would be a lot easier. But, pretty comfortable with Renogy solar panels. I get the 175's I would need at least 2, three would go off the side of the van in a straight line, but provide more power than I would probably need.They are 52.3x26.4. If I go with 100's they are are 41.8 x 20.9 .
With a MaxxAir, Fridge, lights and kitchen, I need 300w on the roof to be close, 400w would be plenty. Trying not to scrimp as this is my first experience and I don't want to run out of juice and prefer to not pull off the vehicle battery unless I am using the 12v for 'emergencies'. Three 175's would be over by about an inch if I lined them up straight across. Four 100's would be the same problem. Not sure how that affects the stealth aspect, but I would like to keep the stealth aspect available if I need to sleep on a public street.
Thoughts on how to arrange to panels? I think putting less holes in the roof by using a rack that clamps to the feet is a good idea but am open to ideas on not only racks but install thoughts.
Thanks
Andy
Hi @MT Boiler

We can help out, but have you performed the required intro post 1st?

read this;

 

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I have (2) 180w Grape Solar panels and my suggestion would be to stick with panels that are just narrower than the stock mounting tabs if at all possible. It makes mounting and servicing them loads easier as you can easily access the mount locations. I bolted my two panels together, ran a piece of 2" wide aluminum bar stock down both sides and then used Vantech's adapters for the roof tabs and small DIY brackets out of aluminum angle to mount to the panels.

That said, I would strongly suggest reconsidering your choice to not draw off of the chassis battery. This is far and away the most reliable source of power you have available. In full sun I'm lucky to pull 250 watts from my 360 watts of solar (Mainly due to the angle of the panels to the sun). My van on the other hand easily pushes 500+ watts to the battery bank. The van might be in the shade, the sun doesn't always shine and solar controllers can fail. With the option to charge off you chassis battery you'll never have to worry about draining (Or worse killing and possibly damaging) your house bank.
 

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First, stealth is a myth. The fan alone will give you away. Don't worry about it.

Second, you are wise to maximize solar even if less would do for now. When you are first starting out, you may not fully appreciate your future desire for comfort and the extent of the van's capabilities to provide it. Your installing a minimum build and using it for a while before advancing further is exactly the smart move we advise. Anything permanent—like solar panels—should be chosen with an eye toward future expansion.

(This advice from someone whose early needs were about as you describe plus a small microwave. We installed 300W. Now having advanced from 100Ah AGM to 300Ah LiFePO4 and added freezer, shower water heating, induction cooktop and Instant Pot, more would be nice, but necessary because we now have B2B—see below.

Even if you get 400W up there, they will not be sufficient for all the reasons Johnny listed and more. It's the van's alternator you want to use, though, not its battery. Invest in a decent B2B charger and solar becomes the icing instead of the cake.
 

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... but provide more power than I would probably need.
No such thing. Actual output rarely comes close to their rated output. Fixed horizontal panels get an average 25% reduction right off the bat. I have 4x100W and have only seen 300W a few times, such as Arizona at high noon. Here on the PNW coast, I rarely see 200W. Right now, under a winter cloud cover, I'm getting a whopping 15W. Many folks also find themselves wanting more/different batteries a year or two down the road. Max out your available roof space and you will never regret it.
 

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We installed a Orion Stealth Roof Rack and were able to mount 4 of the Renogy 100 watt panels east/west and a MaxAir in the rear. It was a tight fit so the measurements had to be right on. We only have a 1000 watt system with 2 100ah batteries. So far we are very happy with our set up.
 

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I mount solar panels on vans the same
I fit 2 NEWPOWA 200's on my 136, plus a maxxfan and skylight. I mounted them sideways. My philisophy was fit as much up there as I could fit, to set you up for any future add-ons. And I'm glad i did.

View attachment 93278
I use 1515 rail instead of unistrut but otherwise do it the same way - fastened to the cleats.

400 watt is a good minimum.

I am mixed about roof exhaust fans because in this area it is just so hot in the summer.
 

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I am not planning on using a battery bank but a Bluetti 2000w Power Station. Can I plug the battery charger into that??
Another thing to think about before I put the walls on!!
Thanks
You might want to read this thread of @Bromaster5;


The “Ecoflows” or “Bluettis” have specific array inputs that need to be satisfied IIRC.



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Or maybe this one ?



Not sure which 2000W Bluetti you are considering.

The tough issue with these “All in Ones” are charging them up & the expensive proprietary connection cord or solar panel systems.


Maybe @Boondogger will post her experience for you.
 

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Hi,
One thing to have a look at before you make a final decision is this test of MPG penalty for solar roof racks on a van
Basically the extra aero drag of the panels/rack can cost as much as 2+ MPG, or less thant 0.5 MPG depending on how much solar you mount and how you mount it.

I use a single large (315 watt) panel mounted as far back as possible and as close to the roof as possible with no rack - it just mounts to the roof with four angle brackets. All this to reduce aero drag. This has worked well for us and for the same loads as you have provides plenty of solar for most of the year where we use it.
Automotive tire Tire Window Bumper Vehicle


The number of amp-hrs you get from a given panel setup depends strongly on the season of the year and the part of the country you are in. You can use PVWatts to estimate how many amp-hrs you will get out of a solar array depending on loaction and time of year. This page gives some info on how to use PVWatts to tell you how much solar a given set of panels in a given location at a given time of year will produce for you.

The chart below will give you some idea how much solar varies with where you are and time of year .
It tells you how many amp-hrs you get on an average day for 200 watts of solar on the roof for several locations and time of year. Your loads are about the same as mine, and will probably be roughly 60 amp-hrs a day.
If you have more or less solar, just ratio it up or down - eg if you have 400 watts, double the amp-hrs shown on the chart.

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Another thing to consider is that how much solar you need depends a lot on how you use the van. Some people boondock for several days in locations that have no place to plug in and get a lot out of solar. Others drive almost every day and really rarely would get any benefit out of solar because their house battery is charged by the alternator.

Gary
 

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Hi,
One thing to have a look at before you make a final decision is this test of MPG penalty for solar roof racks on a van
Basically the extra aero drag of the panels/rack can cost as much as 2+ MPG, or less thant 0.5 MPG depending on how much solar you mount and how you mount it.

I use a single large (315 watt) panel mounted as far back as possible and as close to the roof as possible with no rack - it just mounts to the roof with four angle brackets. All this to reduce aero drag. This has worked well for us and for the same loads as you have provides plenty of solar for most of the year where we use it.
View attachment 93282

The number of amp-hrs you get from a given panel setup depends strongly on the season of the year and the part of the country you are in. You can use PVWatts to estimate how many amp-hrs you will get out of a solar array depending on loaction and time of year. This page gives some info on how to use PVWatts to tell you how much solar a given set of panels in a given location at a given time of year will produce for you.

The chart below will give you some idea how much solar varies with where you are and time of year .
It tells you how many amp-hrs you get on an average day for 200 watts of solar on the roof for several locations and time of year. Your loads are about the same as mine, and will probably be roughly 60 amp-hrs a day.
If you have more or less solar, just ratio it up or down - eg if you have 400 watts, double the amp-hrs shown on the chart.

View attachment 93279

Another thing to consider is that how much solar you need depends a lot on how you use the van. Some people boondock for several days in locations that have no place to plug in and get a lot out of solar. Others drive almost every day and really rarely would get any benefit out of solar because their house battery is charged by the alternator.

Gary
🤔🤔

Oh ,,, Do I Need the Sun?

2 - 100W in series ,,, 40V @ 5amps input max ,,, got 1W ,,, Near Seattle

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Discussion Starter · #17 ·
I fully intend on being a fair weather traveler!! Winters in the south summers in the mountains!! Visiting National Park is my primary interest. This van to me is a platform for me to get there. So I definitely will add solar and might just use the 12v as a backup. The Bluetti will last me three days on my power usage estimates. But if it is crappy weather I don't plan on being there!!
 

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I just bought my Promaster, 136, 2500, HR. Trying to figure out how to 'arrange' solar panels on the roof.
Definitely adding a Maxxair to the back of the van, centered, I think. I am looking at after market roof racks, I think that would be a lot easier. But, pretty comfortable with Renogy solar panels. I get the 175's I would need at least 2, three would go off the side of the van in a straight line, but provide more power than I would probably need.They are 52.3x26.4. If I go with 100's they are are 41.8 x 20.9 .
With a MaxxAir, Fridge, lights and kitchen, I need 300w on the roof to be close, 400w would be plenty. Trying not to scrimp as this is my first experience and I don't want to run out of juice and prefer to not pull off the vehicle battery unless I am using the 12v for 'emergencies'. Three 175's would be over by about an inch if I lined them up straight across. Four 100's would be the same problem. Not sure how that affects the stealth aspect, but I would like to keep the stealth aspect available if I need to sleep on a public street.
Thoughts on how to arrange to panels? I think putting less holes in the roof by using a rack that clamps to the feet is a good idea but am open to ideas on not only racks but install thoughts.
Thanks
Andy
you can use uni strut channels, made for electrical installations. they come in 10' lengths. lowes & home depot have them. see the attached file for the roof brackets, there are cheaper versions, but these look very well made
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We installed a Orion Stealth Roof Rack and were able to mount 4 of the Renogy 400 watt panels east/west and a MaxAir in the rear. It was a tight fit so the measurements had to be right on. We only have a 1000 watt system with 2 100ah batteries. So far we are very happy with our set up.
Do you have pictures of how you mounted 4-400 watt panels. I am struggling just figuring 1000 watts and I will have no fan or ac on the lid.
 
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