Solar Panels on School Bus

Steven Lake · November 2014

Okay, my new super project for next year is to convert a school bus into a lean, green, mobile home machine. In other words, I'm taking an old stripped down school bus and turning it into a tiny home on wheels. In a sense a "roll your own" motorhome. As such I'm considering putting solar power in it so it doesn't always need to be hooked to the grid or run off the bus battery whenever it's parked. As such, in my research I came across a problem I haven't found an adequate answer for. I'm looking at having a system for the panels where, once I'm parked, I can lift them up into position to grab the most sun and lower them down and lock them in place for transport.

However, once I'm on the road it's pretty much a given, at least in my mind, that those panels will get destroyed unless I have some kind of shock mount for the panels. As such, what would you guys suggest I have for the mounting rack for them to achieve both the movability, and also shock isolation needed to keep them from being destroyed in transport? No point paying hundreds for panels only to see them destroyed the first time I shift into drive. >.<;;

westbranch · November 2014

Re: Solar Panels on School Bus

my first thought was about a single axis tracker that Dave Angelini posted about. I cant find his post but it is along the lines of what is on page 8 and after in this document.. http://www.nrel.gov/docs/fy08osti/42769.pdf

Cariboocoot · November 2014

Re: Solar Panels on School Bus

There's a few folks on the forum who have done similar conversions.

We're working on the idea of putting all such threads under an RV category so they'll be easier to look over.

zoneblue · November 2014

Re: Solar Panels on School Bus

Mean time you could give this google search term a whirl.
https://www.google.co.nz/?gws_rd=ssl#q=site%3Aforum.solar-electric.com+AND+%28%27school+bus%27+OR+rv+OR+coach+OR+motorhome%29

Theres one guy in particular that has 2kW mounted in two tiltable rows either side.

PV are impressively strong, i think the biggest worry to my mind is flying stones. Tough but brittle is how id describe them.

Steven Lake · November 2014

Re: Solar Panels on School Bus

Cariboocoot wrote: »

There's a few folks on the forum who have done similar conversions.

We're working on the idea of putting all such threads under an RV category so they'll be easier to look over.

Hey, that sounds like a great idea! I might even be able to steal some ideas on wiring, battery setup, etc, because after the panels the wiring closet gear is my next concern. But I put that lower on the list as it tends to be a bit more durable. Also, we might even be able to share a few layout ideas for maximum efficiency.

zoneblue wrote: »

Mean time you could give this google search term a whirl.
https://www.google.co.nz/?gws_rd=ssl#q=site%3Aforum.solar-electric.com+AND+%28%27school+bus%27+OR+rv+OR+coach+OR+motorhome%29

Theres one guy in particular that has 2kW mounted in two tiltable rows either side.

PV are impressively strong, i think the biggest worry to my mind is flying stones. Tough but brittle is how id describe them.

Interesting. I've always considered them rather fragile. Maybe it's all the glass on them. Even so, being a bit overly paranoid is better than insufficiently and wishing you'd been more paranoid. lol. It's sure kept me out of trouble. ^_^;; Also, your google link didn't work.

zoneblue · November 2014

Re: Solar Panels on School Bus

Its not your average glass. Its toughened safety glass. You can see the rated loading in teh specs, but typically 5kPa. There are reports of people standing on them without breaking.

However as discussed, a realtively small flying stone will shatter the panel, even thought the panels are certified to withstand 25mm diameter hail. A few years back we were doing a job on a house with pv, and a neighbour tossed a few peices of 3/4" agregate at the roof (in protest of the noise), hitting one panel and shattering it. There are also reports here of line trimmers flicking stones doing the same.

Cariboocoot · November 2014

Re: Solar Panels on School Bus

Same pressure-point principle as those little 'safety escape' hammers use for shattering car windows. Just as effective too.

Here's an odd anecdote: I keep having to put windshields and lenses in my 4Runner because they get broken by flying stones. But not on the gravel logging roads! Always it has been out on the main highway where someone going in the opposite direction has kicked a stone up - and cost me another $100.

scrubjaysnest · November 2014

Re: Solar Panels on School Bus

I use two stands made of 3/4 inch pvc; set it up in the sun at the angle needed. Connection between the panels and the controller is 15 feet of 10 AWG marine wire. A little effort to move them around but no more then maybe climging up on top of the bus to position panels. Most RV'ers have the panels roof mounted with aluminum angle. Some use Z brackets.

BilljustBill · November 2014

Re: Solar Panels on School Bus

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Steven Lake wrote: »

Okay, my new super project for next year is to convert a school bus into a lean, green, mobile home machine. In other words, I'm taking an old stripped down school bus and turning it into a tiny home on wheels. In a sense a "roll your own" motorhome. As such I'm considering putting solar power in it so it doesn't always need to be hooked to the grid or run off the bus battery whenever it's parked. As such, in my research I came across a problem I haven't found an adequate answer for. I'm looking at having a system for the panels where, once I'm parked, I can lift them up into position to grab the most sun and lower them down and lock them in place for transport.

However, once I'm on the road it's pretty much a given, at least in my mind, that those panels will get destroyed unless I have some kind of shock mount for the panels. As such, what would you guys suggest I have for the mounting rack for them to achieve both the movability, and also shock isolation needed to keep them from being destroyed in transport? No point paying hundreds for panels only to see them destroyed the first time I shift into drive. >.<;;

Going down two lane or four lane highways and at legal speeds of 65mph-75mph, think about the wind pressures as they face upward on your bus's top. To get a "feel" of what your panels go through, take 5 minutes and park on the shoulder of your nearest Interstate Highway, with your blinkers on, and stand outside the front or back of your vehicle. "Feel" the wind pressures and wind turbulence when a single or double trailer semi goes/blows by....

As a college kid, I clearly remember the conversation between two college professors about their trip from Dallas's State Surplus Warehouse. They had found the slate tops to a pool table and had them standing on the edge in a small 5x8' two wheel trailer. Also, the found a new 4x8' sheet of some fancy graphic wood grain on a new sheet of Formica which they had tied to the roof of their vehicle. On the two lane highway, and 3/4's the way back home, they met a semi truck and trailer. The rough ride in the trailer cracked one of the slate halves. The truck's wind currents caused the Formica sheet to shatter into 2 ft. and smaller pieces to which they gathered from the highway and ended up tossing the remains of both into the college dumpster....

Even as I toted the garage sale solar panel powered surveillance trailer I bought, with the panels locked in an vertical edgewise manner, I got the "Willies" just knowing that two uncovered Kyocera 135w panels were locked in the transport mode.....right behind my pickup tires.... ;>)

Good luck with your choice,

Bill

Steven Lake · November 2014

Re: Solar Panels on School Bus

Yeah, I'm looking to raise the panels when the bus is stationary and lower them for travel. I may even add a "wind coat" as we call it. That's basically a fancy air foil that goes around the panels when you're going down the road. I don't have a picture, but if you imagine a spoiler of sorts in front of the panels and some simple tarp material on the sides, you'll get the basic idea. Someone proffered the idea to me and I like it. Plus it wouldn't be much effort to do really. If I had a wind coat I could also add another tarp over top of the panels to protect them from raw shock should they get hit with a stone. Not sure how I'd pad it, but that's part of the process of figuring out how this stuff will work.

Also, I ran across an idea from another forums that I think will rock and should eliminate the need to climb on top every time I want to deploy them. Oddly enough, I found it while working with the "single axis tracker" idea presented by westbend. The idea they used is pretty simple and outright genius in my opinion. The basic idea is you have one end of the panel connected to a pivot mount (a swivel pin mounted to a frame on both sides) and the other connected to a linear actuator that's mounted to the panel on a swivel bar of its own. Extend the actuator arm, the panel rises. Retract it and the panel lays down. I'll probably have to kludge mine a bit as theirs was just an idea, but in concept it works. The only trick will be actually getting a working system. Then, if I'm able to, I might even hook the frame to an electric turn table and be able to point the panels anywhere I want, not requiring me to have the bus facing a specific way.

Iceni John · November 2014

Re: Solar Panels on School Bus

I have eight Sharp 255W panels that sit in tilting support frames hinged to a central walkway between my two roof hatches. For travel they sit down against the roof at 21 degrees below horizontal, secured so they cannot move at all. When parked they can be raised to horizontal or to 21, 33 or 45 degrees up. The entire walkway and support frames assembly is made from 6061 and 6063 aluminum, and all hinges, struts and hardware are stainless. The panels' support frames will isolate any stresses or loads from the PV panels themselves, and the panels sit on closed-cell foam to further isolate them. The support struts are telescoping stainless tubes that slide in aluminum T-track, and the T-track and upper hinges pivot to eliminate any loads other than purely compressive or tension. Today I just finished the panels' feed cables: each panel has a 10-2 tray cable with MC4 connectors that goes to a roof-mounted combiner box for each side of panels, from where 4AWG downfeed cables take the power to two 50A Carling C breakers and two Morningstar TS-MPPT-60 charge controllers that will charge two separate banks of batteries for house power. Because each side of panels will be tilted at a different angle in winter, I have to use separate charge controllers - another reason is redundancy, so even if one CC or one bank of batteries failed I would still have at least 50% of my house power capacity. I am setting my bus up for long-term off-grid use, so it has 220 gallons of water and 180 gallons of waster tanks, enough for one person for at least a month or two people for a fortnight, and that's still taking a proper shower every night and cooking/living/etc normally.

On the walkway I also have two water quick-connect outlets for washing down the panels, easier than dragging a hose or lugging buckets of water up there. There's also space for two eventual solar water-heating panels that will tilt like the PV panels. My plan is to be as self-sufficient for house power as possible, and to use as little LPG as possible. My 3500W Champion generator is converted to LPG, mainly because I don't anticipate needing to use it more than a few times a year, and LPG is better than gasoline for such usage.

It's been a big project to get the roof ready for solar, but now everything's ready to put the panels up there. I won't actually do that until I've bought the house batteries and begin to use the bus, maybe in a year or two depending on how quickly I build the interior.

John

vince · November 2014

Re: Solar Panels on School Bus

I'm currently working on a similar challenge to tilt the panels on my tiny mobile house with a low pitch roof. Do you have any pictures to show how you managed to construct your frame? I'm planning to work with two linear actuators to tilt the 3 panels remotely, and was going to use unistruts but maybe there are better options. Thanks

Iceni John · November 2014

Re: Solar Panels on School Bus

vince wrote: »

I'm currently working on a similar challenge to tilt the panels on my tiny mobile house with a low pitch roof. Do you have any pictures to show how you managed to construct your frame? I'm planning to work with two linear actuators to tilt the 3 panels remotely, and was going to use unistruts but maybe there are better options. Thanks

I first made the walkway that runs between the two roof hatches - it has two 25' lengths of 1.5" x 1/8" 6061-T6 angle (plus a bit more to make the full 26' length), with six and a half 12" x 48" pieces of 1/8" aluminum treadplate between the 6061 angle. The whole assembly sits about 4" above the roof, and is attached to the bus's roof ribs that are spaced every 19" with 3/8" stainless bolts coming up through each rib from underneath, then with EPDM rubber washers as seals, stainless washers, 6063 tube as spacers, 6061 1"-wide strips as transverse and longitudinal bracing, and stainless NyLok nuts. The space under the treadplate is enough for five outdoor-rated electrical boxes that are again bolted to the roof ribs, under two removable sections of treadplate for easy access. Two of these boxes are combiner boxes for the PV panels - each side's panels has a feed cable that runs inside some 1" aluminum tube as conduit back to the box, and each panel is fused with its own 12A fuse, then combined to bus bars for the Pos and Neg 4AWG cables that run through the hollow roof ribs down to the breakers under the floor next to the charge controllers. The controllers are mounted in the luggage bay, and the house batteries' are on two slide-out trays next door, literally inches from the controllers but separated by a steel wall. (Remember this is a real bus, not a S&S RV, so everything is made to last for millions of miles!).

Each panel sits in a support frame made from a 16' length of 1.75" x 1/8" 6063-T52 angle, plus a 24" section riveted on to make the full 17.5' length to accommodate the Sharp panels, bent round in a rectangle and gusseted at each corner. Each frame is hinged to the walkway with two 4"-long stainless hinges and twelve 1/4" stainless bolts, so wind gusts won't be worry even when the panels are fully raised. Each frame has two telescoping stainless support struts with Valco stainless snap buttons, and each strut pivots at its top onto a 3"-long stainless hinge on the frame, and slides at the bottom inside a hinged length of aluminum T-track. The eight pieces of T-track on each side are each riveted to lengths of aluminum piano hinge that are bolted to a 25' length of 1" x 1/8" 6061-T6 angle, and this angle is bolted through each roof rib similarly to the walkway. I made simple clamps to positively secure each panel down against the roof when driving, and the panels can be easily raised or lowered by hand, only using some stainless wingnuts - no tools required! Each panel sits inside its support frame on some pads of closed-cell foam, and is secured with four 5/16" stainless bolts and NyLok nuts that clamp against the panels' top surfaces: this is completely secure, but if I had to replace a panel it would take only a few minutes.

It was a lot of work to make it this way, but I want something that will never need any routine maintenance or work and that will work well for many years in all weathers. I could have slapped something together from some two by fours, but that's not my way! Besides, it looks really good up there - several folk in the RV yard where I store and work on my bus have commented that it looks like it came from the factory that way!

If you're ever in Orange County CA I'll be happy to show you what I've done.
John

vince · November 2014

Re: Solar Panels on School Bus

Thanks for the detailed description. A picture would still be helpful to see if my "guided imagination" is accurate.

Steven Lake · November 2014

Re: Solar Panels on School Bus

Iceni, cool info!

vince wrote: »

I'm currently working on a similar challenge to tilt the panels on my tiny mobile house with a low pitch roof. Do you have any pictures to show how you managed to construct your frame? I'm planning to work with two linear actuators to tilt the 3 panels remotely, and was going to use unistruts but maybe there are better options. Thanks

Sadly, no. All I've got is the description which I posted, but nothing else.

But I was able to visualize approximately what they were building.

Steven Lake · December 2014

Re: Solar Panels on School Bus

HA! I'm finally starting to get this dumb thing figured out. I took the idea given to me on another forums (see above) and began finding the parts I need to make this work.

First, the base swivel:

http://www.lowes.com/pd_383402-93052-BP6612_0__?productId=50146394

That sucker will anchor perfectly to the roof and is capable of dealing with 190mph winds against the panel (the sheer strength on this thing is insane!) onto which I mount a simple square frame for lifting the panel up to 80 degrees vertical. The base will in turn be rotated using a low RPM gear drive and drive chain. You'd have to see to understand what I'm talking about, but it's only two moving parts and will be the total solution to what I need.

And now that I've had time to mull this over the design is gonna be easier than I thought. One extension and one low rpm motor, a bunch of odd parts, and we're in business.

westbranch · December 2014

Re: Solar Panels on School Bus

why not use a worm (gear) drive rather than a chain? completely enclosed

Attachment not found.

Steven Lake · December 2014

Re: Solar Panels on School Bus

Where the **** did you find that!? o_0;; I didn't even know those existed. If I had I've have used it in my design. Now that I do I'm gonna research that and see how to implement it into my panel system. Question though. I don't see a drive motor. Just a worm drive ring gear. Do I have to connect it to an outside motor? Just asking so I know where to focus my research.

westbranch · December 2014

Re: Solar Panels on School Bus

do a Yahoo search , not Google, and there are some pictures down the page plus all the links...

hth

ps they also use them on tracking arrays, big ones , try this one for info http://www.kinematicsmfg.com/download-form/thanks-download-form/

Steven Lake · December 2014

Re: Solar Panels on School Bus

http://www.offgridquest.com/95

Ran into this story here today and from what I can see with these designs that run solar on the roof, like mine will have, I'd probably be best to simply flat mount it to the roof and be done with it. If all of them are doing that and it seems to be working for them, I may as well save myself the trouble and do the same.

jimindenver · December 2014

Re: Solar Panels on School Bus

As far as the panels being damaged, I've never heard of one being chipped on a RV in 3 years of going to the various forums. None of the solar panels in our neighborhood got damagedin the hail strom this spring that took out windows, siding, damaged cars and totaled our travel trailer.

As far as a powered lift system, I'm interested in the systems they use for powered awnings. Those even have wind sensors that would drop the panels when needed. Doing it manually would be too much of a hassle on our RV unless we were in one spot long term. I also thought of using the tongue frame on the trailer to anchor a collapsible mast with two panels and a tracker. Fold the panels together and drop the mast for travel. Unfold and lift for set up and turn on the tracker. How I would design and build such a device, or even if it is feasible, I have no idea.

techntrek · December 2014

Re: Solar Panels on School Bus

Steven Lake wrote: »

http://www.offgridquest.com/95

Ran into this story here today and from what I can see with these designs that run solar on the roof, like mine will have, I'd probably be best to simply flat mount it to the roof and be done with it. If all of them are doing that and it seems to be working for them, I may as well save myself the trouble and do the same.

This is almost always the solution for RVs, unless you have the time to babysit portable panels.

Endurance · December 2014

Re: Solar Panels on School Bus

Mine are all mounted flat on my boat. It works great as long as you have enough room.

BB. · December 2014

Re: Solar Panels on School Bus

Seen a few RVs that have made "awnings" out of a set of solar panels... Fold against the side of the RV when traveling.

-Bill

Steven Lake · January 2015

Re: Solar Panels on School Bus

Well, given that I've tried to destroy the last several sets of solar panels I've touched (call me Mr. Clutzy/Bad Luck) I'm really starting to think that my best bet will be to just hard mount them in a fixed orientation on the roof and call it good. Because at the rate my luck has been going lately, I'd almost be better off going the simplest way possible to avoid turning my nice brand new panels into something that looks like a ripoff from a Van Gogh exhibit. >.<

Solar Panels on School Bus

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