Advice wanted on Mounting 2 Solar Panels on Caravan Roof

Submitted: Monday, Dec 15, 2008 at 14:00

ThreadID: 64295 Views:25919 Replies:8 FollowUps:6

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PeterInSa

Am looking at DIY installing of 2x 80watt BP Poly Crystal Solar Panels on the roof of our 21’6” van. Any comments on the items below appreciated. Will only be used for TV at night and to run our Fluro’s. Getting 2 old to lug the Honda E20i in and out of our Cruiser.

Since I do not know the location of the roof supports am going to mount the panels just forward of the roof top air conditioner (on the flat section NOT on the slope) with an aluminium right angle strip 75mm x 50mm for the full length of each side of the solar panel , Riveted onto the panel (75mm) and the van roof (50mm).ie Panel approx 25cm above roof. Rivets approx 150mm apart.

Of course, AL strip and rivets on the roof will be silicon’ed in, as will be the rivets and strip to the Solar panel.

Have seen some vans using screws, but I prefer rivets as they can take more vibration, before coming loose, the downside is that they can wear thru. Have seen some 80 watt panels held on by 4 angle brackets each having two screws to the roof and two to the Solar panel.

Will use the standard White Conduit and plastic saddles to connect the roof top units together and go thru the roof to the floor then the boot via a Floor to ceiling cupboard.

Will mount the Controller in the front boot, will cut down cabling and its not something that I want to look at often.

Am also think of installing the right angle strip in the front forward direction of the solar panel as have heard that some panels are working loose, because of the wind pressure of passing semi’s. However do not know if this pertains to solar units that have only 4 brackets or units that have the full AL strip on both sides

Any comments on the BP Ploy Crystal as am looking at Ordering/Buying them this week prior to the New Year price rise.

Peter

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Reply By: MEMBER - Darian (SA) - Monday, Dec 15, 2008 at 14:14

Monday, Dec 15, 2008 at 14:14

Haven't done such a job myself, but couple of points from my Colin Rivers book on Solar - he suggests making a very light sub frame to hold the panels, then attaching that frame to the roof with marine grade Sikaflex - used correctly, the Sikaflex bond must end up like a chemical weld - might survive a nuclear blast ! And no drilling it would seem, apart from the circuit cable. BTW - if drilling, closed pop rivets might be the go - reducing leak potential.

AnswerID: 339842

Reply By: hazo - Monday, Dec 15, 2008 at 14:32

Monday, Dec 15, 2008 at 14:32

Peter
I have done several solar installs on my previous vans.
Firstly 50mmx50mmx3mm aluminium angle, is perfectly adequate for the panel supports and easily available and cheaper than the 75mm.
I would steer away from silicones and go with Silastic 292 or Goldflex (half the price of Sikaflex).
I used 3/16" alloy rivets to fix to roof and 12mm stainless screws to fit panels to side brackets (no sealant), as you may need to remove a panel down the track.
Beware of steel electrical conduit saddles as they rust like buggery!
I found that it was much neater to Sikaflex the conduit to the roof (hold in place with "gaffa" tape till dry) and ran my conduit to a plastic conduit box then out the back of the box directly through the roof into an overhead cuboard.
A conduit box can be also sealed to the roof much easier and also looks much neater.
I then ran the cabling from the regulator in the top cupboard down through the cupboards to the floor and through underneath, then in 20mm flexible conduit to the battery compartment,in the boot.
Fit a decent quality regulator like a Morningstar Prostar or similar, and allow enough sizing (amperage) of regulator in case you decide to add another panel later.
Also use good quality correct sized cables to avoid any voltage drop.
Most installers use too small a cabling for the panels they fit.
Brian

AnswerID: 339843

Reply By: Motherhen - Monday, Dec 15, 2008 at 16:04

Monday, Dec 15, 2008 at 16:04

Hi Peter - I think you will want to check the monitor more often than you think. If you can possibly run the wires to somewhere you can easily see the controller in the van, you will appreciate it. Are you having two batteries?

Motherhen

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AnswerID: 339854

Follow Up By: PeterInSa - Monday, Dec 15, 2008 at 16:41

Monday, Dec 15, 2008 at 16:41

Motherhen,
We have Solar on our House 175w x 7 with a remote RF Monitor and don't look at the monitor. All I want to do is charge the 2 x 120A/h batteries. ie set and forget. 2 x 80watt panels and 2 x 120Ah batteries will more than cover our use.

Will get an electronic monitor, but do appreciate how others could just purchase a $90 regulator with no readouts.

Appreciate your comments and of course, with experience, I could regret my current idea of the install.

Peter

FollowupID: 607394

Reply By: PeterInSa - Monday, Dec 15, 2008 at 16:30

Monday, Dec 15, 2008 at 16:30

hazo,Darian,All,
Since my post above have further looked into the mounting methods.
My understanding now is that the roof of the van is not necessarily stuck down to the roof supporting frame. One installer in Adelaide uses the Al Angle and puts it as close as possible to the edge of the roof and the vertical side but not over the AL Strip that has the plastic fitting. The other side is rivetted to the roof panel.

Another installer uses square tubes (2) going from one side of the van to the other and screws/seals it into the AL Strip with the Plastic Fitting to avoid rivets/screw in the roof. The square tube can be siliconed to the roof in the middle. Various users of Silicon are not as impressed as myself based upon their experience ie. over time it can leak.

As Big Mal use to say "Life was not meant to be easy" especially if your a DIY'er.

Was told by a mate "pay for an installer to do it then if it leaks/blows off the roof you can claim against him". The thing is if it happens when you are out in the sticks and it ruins your trip, getting your money back for a faulty install is the last thing on your mind when you have a hole in the roof and rain coming in.

Peter

AnswerID: 339859

Reply By: Peter_n_Margaret - Monday, Dec 15, 2008 at 18:14

Monday, Dec 15, 2008 at 18:14

1. Sikaflex only, no holes, no silicone.
2. Consider hinging one side to allow cleaning out the dirt, leaves and crap. Very difficult otherwise.
3. Select a location that allows you to add a couple more panels later.
4. 25mm is a bit too close to the roof. Performance degrades when they get hot. The instructions will recommend a bigger air gap.
5 Use muli-strand cable of generous proportions to reduce voltage drop. Again, see Colyn Rivers book.

Cheers,
Peter
OKA196 Motorhome

AnswerID: 339870

Reply By: Dunaruna - Monday, Dec 15, 2008 at 18:54

Monday, Dec 15, 2008 at 18:54

Cleaning panels is often overlooked. Mounting close to the edge affords easy access with a ladder.

I always use SS screws and glazing grade silicone. Never had a problem.

AnswerID: 339875

Reply By: MEMBER - Darian (SA) - Monday, Dec 15, 2008 at 21:33

Monday, Dec 15, 2008 at 21:33

Seeing you are obviously serious and organised about this project Peter, I point out that the Rivers book on solar has everything any handyperson could possible want to know on the subject - including the finer points of regulator choice - my solar will be installed by the van maker (I'm ordering soon) but I still wanted to be somewhere 'in the picture' regarding technicalities. Such as wire gauge, regulator types etc........... it was worth the $..... and hell..... I've even made up a Excel spreadsheet on possible performance of the system I'm aiming for :-o).

AnswerID: 339925

Follow Up By: PeterInSa - Tuesday, Dec 16, 2008 at 14:37

Tuesday, Dec 16, 2008 at 14:37

Darian, All
Having looked at a Solar system installed by a van maker, I would not want a similar install on my van. A friend who has been on the road for a number of years has seen a number of installs (a small minority) by professionals that he considers are not up to scratch. So its a good thing you have a Solar guide book.

At the moment am thinking of having the units at the rear of the van mounted on 2 Gal tubes across the van with welded triangle plates on the ends screwed (3x4) down thru the AL edging to the top of the side walls with Silastic etc. With plates welded to the tubes to screw into the Solar units.(would prefer the tubes/plates to be AL but will go for steel for strength.)

The front of the units will have a 50x75mm AL angle Silastic to the roof and screwed to the unit. In the middle of the roof underneath the 2 tubes and joining them will siliastic/silicon in another AL tube for further support.

Will have this design checked out by a Caravan manufacturer prior to going ahead with it.

Peter

FollowupID: 607525

Follow Up By: MEMBER - Darian (SA) - Tuesday, Dec 16, 2008 at 15:45

Tuesday, Dec 16, 2008 at 15:45

Good point - solar installation could be no better than than some of the other horror stories we see here and there about van builds - I'll be going over every detail of my van at the time of ordering - my maker is low volume and not cheap (read hell !..... am I really paying that much ?), so I'm expecting top quality attention to specs and detail. Current owners I have met suggest that is what I'll get.

FollowupID: 607530

Follow Up By: PeterInSa - Tuesday, Dec 16, 2008 at 18:24

Tuesday, Dec 16, 2008 at 18:24

Darian,
If your van manufacturer's workshop is in an Adelaide suburb starting with "L" you will get a great van that will last you the rest of your life.

I cannot afford one. Hope mine lasts as long.

Peter

FollowupID: 607556

Follow Up By: MEMBER - Darian (SA) - Tuesday, Dec 16, 2008 at 18:55

Tuesday, Dec 16, 2008 at 18:55

Negative - I went there but they seemed not to want my $ - I left them with my typed up list of specs and points needing discussion (it was a bit lengthy) must have seemed overkill to them - never heard from them again. I'm going with one of the hoards of van makers in Victoria ....... in a suburb starting with B .... :-o) ..... possibly the only mainstream maker in Vic of what I call "rough roads capable" vans.

FollowupID: 607561

Follow Up By: Member - Mike DID - Thursday, Dec 18, 2008 at 07:16

Thursday, Dec 18, 2008 at 07:16

Saw a "professional" panel installation on an AVan - positioned between two skylights.

This would ensure that a shadow would fall on a corner of the panel, except when the sun was directly overhead.

FollowupID: 607806