Roof top tight spacing solar panel installation

[SatelliteBob]

I have looked to see if this has been covered and may not be typing in the correct search so I will try this way.

I am installing four 400watts panels on the roof of my Gray Hound bus conversion. I have installed some Unistrut on the roof to set the panels on. I have purchased tilt mounts to attach the panels to then the tilt mounts will bolt to the Unistrut. I will have very little room left to get around the panels and less to get to hardware holding the panels in place. My thought is to mount the base plates for the tilt on to the Unistrut then the upper part of the tilt to the solar panels. One side of this installation will be easy as I can get to the hardware in the center of the bus to install and tighten. The problem as I see it is getting to the hardware that hold the panels from the other side. Can the panels be walked on or can I at least lay on them to get in this hardware. I keep trying to figure away to do this part of the installation ( watched some video and online searches) . The mounts are supposed to be able to tilt so I can set them for more sun as needed but I can not see how this can be accomplished if i can not get back the hardware later. The panels I have are 44" wide and 64" long the tilt assemblies are 45" long to bolt to the 44' width of the panels. I have installed three sets of Unistrut to the roof, one centered and two each side at about 40 inches from center. The Bus is 102" wide but has a curved roof outer section and will not allow me to get the full 45" spacing. Due to the length of the panels I have chosen to install three of the tilt units on each panel, not sure this is required or just over kill.

Any suggestion here would be helpful.

 

[HRTKD]

If you are having so many issues with installing the tilt mechanism, how are you going to operate the tilt mechanism? I'm not a fan of tilt mechanisms (certainly not manual ones) on an RV roof. When I looked into implementing a tilt mechanism for my RV I found on the Internet that many people that had tilt mechanisms used them the first few times and then never again - it was just too much work.

No, you cannot walk directly on panels. But if you place a couple of 2x10's across the frame it may support your weight assuming you have placed them near where the panel is supported from below. That's still sketchy.

Some pictures would help everyone understand your situation.

 

[SatelliteBob]

I have also read about using them a few times and then never again. I bought them trying to find a solution to mounting these panels. When I started down this path of adding solar to my bus I thought get the largest ( most wattage I could afford ) so I hunted until I found some and made the buy. Now that I have them I have spiraled out of control buying more parts, Unistrut spring nuts, Stainless hardware, and the list goes on. I made the mistake of getting the Unistrut ( Galvanized ) and drilling the roof to mount the panels. Aluminum roof, Galivanted Unistrut, Aluminum solar panels.............my satellite antenna teachings year ago should have warned me about mixing these metals. So I removed the galvanized Unistrut and installed aluminum Unistrut and bought Stainless hardware all around including the tilt up hardware. I really don't see my self on the roof adjusting them but they do seem to be the most logical way of attaching the panels to the Unistrut. The panel manufacture is suggesting there should be a 3" gape under the panels to allow for cooling them. I have the 5/8" Unistrut by adding the tilt frame work I will be very close to the required 3" gape. I have been concerned about the panels vibrating on the roof as I am driving so I want to make them sought. With the small gape between the panels I have been trying to find a solution on tightening the hardware after I get them on the roof. Trying to avoid a AH AH moment. I will look at getting a picture to help

Thank you for your input

 

[HRTKD]

I used aluminum strut (not Unistrut) on the roof of my camper. It saved a lot of weight and some money given that it came from a salvage yard. But since the channel didn't conform to a standard Unistrut format it was a lot more work to deal with.

I have four 420 watt panels, two on each side at about a 10° angle due to obstructions and the crown of the roof. I had to get a bit creative.

 

[SatelliteBob]

Okay I have gotten the three rails installed on the bus roof now, see pics. I ordered five more 10' rails to go from center to the outer rails. I will cut the 10' down to a 49" measurement and attached the tilt setup to the top of them. It looks like this will give me approximately 2.4" air gap under them, except where the roof curves. This should allow a 6" gap at the middle of the bus roof and I hope will allow me to get the hardware tightened.

 

[HRTKD]

I wonder how it would have worked out on my trailer to lay three rails on the roof instead of four. The crown on mine might be a bit more than on yours. I would have to what-if that on CAD to see. I had a lot more roof obstructions that you do.

 

[SatelliteBob]

I went with the three trying to cut costs, I don't think four rails would make much difference in my case as they would have been so close to each other in the center of the roof. I am going to try and set the tilt units on top of the next level of Unistrut to allow the close placement of the panels to match from one side to the other. I am old school and not useful using the CAD programs so I need to cut and measure and adjust as I see fit.

My 40' bus has two roof top AC units one front and one rear, in the middle just behind the solar placement I have a power vent to help move some air in or out as needed. The roofs build as seen in the pics shows the aluminum strips ( about 5' wide ) going from side to side, under this is a structure/frame rib that is a sort of U shape that the rivets are attached to. This setup means there is a slit lift where the strips over lap allowing an area for rain to run off ( pic) . This also makes a very strong roof in case of a accident. I was able to drill and install riv-nuts at each seam, I used a windshield installation adhesive/sealant around each riv-nut as I put them in place, then after installing the hardware I covered everything with Sikaflex self leveling seal. Fingers crossed I don't get any leaks

 

[steined]

We built a unistrut system on our RV. We also utilized tilt mounts for the panels. It is indeed a PITA to tilt the panels, but we are stationary with only sewer and water in the winter for a couple months so tilting them once for that is more than worth the hassle in terms of output with an over 40% bump where we are (aimed panels to the south tilted to correct angle).

We utilized aluminum double strut for the legs and rails. Probably overkill. We also used galvanized feet and brackets for corners as we couldn't find them in aluminum. We utilized CRC Marine Corrosion Inhibitor at those joints (basically sprayable cosmoline). The tilt mechanism isn't my favorite. It easier to tilt them at an extreme angle in the north than a shallower angle in the south. I might just cut some angle aluminum to length for my fixed tilts. Not sure yet. I would have much preferred a way to link say 2 or 3 panels together and tilt them as a group to reduce the number of knob/wingnut connections too. Might work on that later. We didn't use a gigantic panel so there was enough room to walk down one side of the roof for servicing and barely enough to get on the other side to tilt. My wife can scooch under the panels when down, me, not so much! We will almost always tilt from the side with more room, but this year it was from the side with less room. Takes around an hour - hour and a half to tilt all the panels. Have taken them down in 45 minutes once.

The other reason we went with tilt mounts was for servicing the exhaust fans, and 3 ACs on the roof and the ability to seal/caulk, etc if needed. It took a lot of planning and measuring to make that work, but we managed to make it so we can remove the AC shroud without removing a panel. One nice benefit of the unistrut was that it gave me a place to mount my starlink on the roof too. I do have to move it to a flagpole mount when tilting panels, but the cable is more than long enough and I'm on the roof anyhow so no big deal. Starlink in motion is a game changer though! We did vinyl wrap the rack as the black blends in well with the dark maroon on the top of our RV. Probably wouldn't have needed too with single height strut.

If I could do it over again, I likely wouldn't use double strut. I would likely try to figure out how to incorporate unistrut into a tilt mount, and I'd like to figure out something other than the knob/wing nut for the hinge points as they can come loose. We ended up using purple locttie to make it less likely to loosen over time. Over 2,500 miles I've had one backout completely before the loctite. We used PTO couplers as safeties in each panel just for that contingency. We have bolt/stainless lanyard to the tilt mounts and unistrut in case one of those comes loose, but that seems very low likelihood.

Good Luck! Hope some of this helps and gives you some ideas/pointers.

 

[SatelliteBob]

That's a interesting looking project you have. You did not include a pic of the RV from the side while the panels are done for transport, but I do get the idea of what you did. I have been trying to keep the height down so I don't have to worry to much about low over hangs and trees damaging the panels. I do like the appearance of my bus from the side and did not want to make the solar stand out to much. I think I will miss the mark on this, my bus forum buddies will not like this.

You invested allot of time in your system and I'm sure money, do you like how its working. What voltage did you go with and how much battery storage did you end up with. How many watts are your panels, inquiring mind want to know.

Thanks again.

P.S. I learned a new (to me) trick to day. I was cutting some aluminum with my 4.5 inch battery operated grinder, using a cut off wheel. It was taking allot of time to make some of the cuts. In the past I have used wax to lubricate drill bits for drilling and I had some laying on the tail gate/work bench. I turned on the grinder and held the wax to the blade, wow what a difference. I could cut at least twice or more as fast, 74 and still learning things, man life is good.

 

[HRTKD]

P.S. I learned a new (to me) trick to day. I was cutting some aluminum with my 4.5 inch battery operated grinder, using a cut off wheel. It was taking allot of time to make some of the cuts. In the past I have used wax to lubricate drill bits for drilling and I had some laying on the tail gate/work bench. I turned on the grinder and held the wax to the blade, wow what a difference. I could cut at least twice or more as fast, 74 and still learning things, man life is good.

I use the Diablo aluminum blades in my saws. They cut through extruded aluminum like a hot knife through butter. The only downside is that it leaves quite a lot of small shavings. I try to use a dust collector when I can.

Circular Saw Blades - Diablo Tools

Learn how Diablo's circular saw blades are the best in the world, redefining cutting with their quality and performance.

www.diablotools.com

 

[steined]

That's a interesting looking project you have. You did not include a pic of the RV from the side while the panels are done for transport, but I do get the idea of what you did. I have been trying to keep the height down so I don't have to worry to much about low over hangs and trees damaging the panels. I do like the appearance of my bus from the side and did not want to make the solar stand out to much. I think I will miss the mark on this, my bus forum buddies will not like this.

You invested allot of time in your system and I'm sure money, do you like how its working. What voltage did you go with and how much battery storage did you end up with. How many watts are your panels, inquiring mind want to know.

Thanks again.

P.S. I learned a new (to me) trick to day. I was cutting some aluminum with my 4.5 inch battery operated grinder, using a cut off wheel. It was taking allot of time to make some of the cuts. In the past I have used wax to lubricate drill bits for drilling and I had some laying on the tail gate/work bench. I turned on the grinder and held the wax to the blade, wow what a difference. I could cut at least twice or more as fast, 74 and still learning things, man life is good.

Thanks,

Here is what it looks like from the side. Elevation from the side makes a big difference. I have side rails on the roof to hide the ACs, but I swapped out the noisy and ineffecitve/efficient old Mach 8 15K btu units with Tosot 15K units that were taller anyhow. I'm still under 13'4" but if my coach were a raised rail Allegro Bus I'm not sure what I would have done as I'd be too tall with that rack.



You can see the rails, which is why we vinyl wrapped them to make them less obvious. I'd prefer they be flush, but only so much I could do with what we had. Again, had I used single height strut, it probalby would have been even less conspicuous.

We have a 48V/51.2V system. I had 3 12V 300Ah batteries and just bought a 4th and a balancer and wired them in series. Lots of reasons not to do that from the get go and just use 48V batteries instead, but this was the least expensive way for us to do it. So we have a 51.2V 300Ah battery (~1200Ah 12V equivalent). We have a 250/85 Victron Charger for the solar and 2 48/5000/70 Multi Plus II's in split phase configuration.

Also agree with @HRTKD - those Diablo blades in a miter saw are clutch cutting that aluminum, but my dust collector was next to useless on those chips! Aluminum everywhere!!!!!

 

[HRTKD]

Also agree with @HRTKD - those Diablo blades in a miter saw are clutch cutting that aluminum, but my dust collector was next to useless on those chips! Aluminum everywhere!!!!!

It was like an aluminum blizzard. Catching the dust with my chop saw wasn't too bad but trying to catch it on my table saw was a waste of time.

 

[SatelliteBob]

Folded down and ready for travel they look great. It sounds like a very nice system, I am doing the 24V system myself, like you to cut cost of the first phase of the installation. With the two split phase Multi plus units you should have plenty of power.

 

[SatelliteBob]

It was like an aluminum blizzard. Catching the dust with my chop saw wasn't too bad but trying to catch it on my table saw was a waste of time.

Try adding some wax to the blades and see if the blizzard is better or worst.

 

[HRTKD]

Try adding some wax to the blades and see if the blizzard is better or worst.

I'm aware of that technique when cutting wood. It helps prevent burns on wood cuts. It could be argued that if you're getting burns when cutting wood that the (table) saw is out of alignment. I'm OCD about the alignment of my fence, blade and miter slots.

I sat for a few minutes thinking how a waxed blade would reduce the aluminum blizzard. I don't think I have enough knowledge of how the wax would interact with the aluminum to come up with an opinion on if it would help or not. But it's an interesting idea.

Given that I often TIG weld my aluminum, I would rather not have any wax residue on the cut.

Sometimes I'm lazy and use my aluminum blade that is already mounted when I need to do a quick wood cut. I seem to get a similar cloud of wood dust. So I'm thinking the Diablo blades are taking lots of little cuts, likely due to large number of teeth, which creates a lot of dust.

With regard to your experience with wax on the grinding wheel, I have to wonder if the wax served as a lubricant which prevented binding/grabbing the edges of the cut.