Mounting solar arrays to the roof of a Bigfoot

[HMS_Beagle]

I mounted two 100W Renogy arrays to the top of my Bigfoot 10.4E. A Bigfoot is pretty watertight other than all the holes the factory seems to think is necessary in the roof, I did not want to contribute more. So I used these glue on mounts. I was pleasantly surprised when I received them as they are a heavy ABS molding, the thinnest section is probably 3/8" thick. They are available in "corner" and "side" styles, and can be glued or screwed to the roof. These in the picture have been cut down a bit as I will explain:



I laid them out on the roof and had to use a mix of the corner and side pieces, first because things were in the way, and second because the roof of a Bigfoot is crowned. The mounts are made assuming a flat mounting surface, if the roof is crowned it angles them relative to the flat solar panels. So I got them into position, shined them to mate with the solar panels, then scored them to the roof:



Next I built a simple fixture and milled the to the scored lines. It helps to have a Deckel CNC mill with the universal table that swivels and tilts in both directions! This would not be necessary for a flat roof:



Each one was masked off in preparation for bonding. Their directions suggest Sikaflex or similar, I used 3M 5200 which has a higher claimed bond strength. I lightly sanded the roof and cleaned it with acetone and the ABS mount with mineral spirits (acetone will eat them):



A liberal application of 5200, then dropped in place with solar panels on top to insure everything is aligned. I cleaned the excess sealant and as soon as I could (about 20 minutes) I peeled the tape to leave the edges clean, but left the panels in place until the sealant gelled.



The Fast 5200 takes about 24 hours to really cure (the slow version can take 5 days or more), so I waited until the next day to drill holes through the mounts into the panel frames. Zero holes in the roof. Will they come off? I don't think so, but I will take a look from time to time. The corner pieces nicely guard the corners from branches etc., the whole installation is nestled between the other roof penetrations and is hardly visible from the ground:

[Eugarps]

HMSBeagle,

Wow, is that ever a nice installation! If I'm able to score the Northern Lite I'm looking at, please expect a PM or two. Why spend the money for a fiberglass camper and then drill holes in the roof, if an alternate method of mounting is available? Thanks for sharing.

Bill

[mike_kellie]

I need to learn how to copy and paste on this forum or snip...sorry-

[mike_kellie]

"But I have found one or two occasions where I wanted it - several days parked under trees in heavy shade, cold temps so heater runs a bit. I had to move the truck into the sun for a few hours after 3 days."
I was in your neighborhood this morning at Bothe State Park where I was checking out the site where we are staying in a couple weeks. it was all of "cold and shady".

[HMS_Beagle]

I have two Blue Sky units, both with the IPN remote. They are very programmable, and include complete battery monitoring (with the shunt). The problem I have had with the one in the camper is that when it is set up properly for the Lifeline AGMs, It cycles quickly (10 seconds or so) between absorb and float. If I set the switch over current fairly high, it doesn't do it, but I am not charging to full quite as fast as I should. Blue Sky and I have spent considerable time trying to understand and fix this, without success. They say it doesn't happen elsewhere (and indeed it does not on the one in my boat). Something unique about my camper, though it looks quite ordinary to me. It's a very nice unit but for this one problem.

[work2much]

HMS Beagle wrote:

work2much wrote:
Very clean install and looks like perfect use of roof space. What did you select for a charge controller? MPPT or PWM? Batteries type? Did you wire panels in series or parallel?

Any tips after a couple years of use?

I used a Blue Sky MPPT controller but have had a little trouble with it cycling between float and absorption. Which is odd because I have used them before with good results. For the small extra money you might as well go with MPPT. Definitely wire them in parallel, to reduce the effects of shading. I use Lifeline AGMs, properly cared for they will give you 10 years useful life.

Park in the sun :).

Thanks HMS Beagle! I have the Renogy MPPT controller now that came with the kit from Amazon but am looking to upgrade to something more programmable/predictable. The Renogy goes into "equalization mode" without anyway to predict or control it. Their own literature warns against having anything drawing from batteries during this mode but after numerous correspondence with Renogy they admit that there is no way to accurately follow their warning. The Blue Sky, Morning Star and Outback are all units I am considering.

[HMS_Beagle]

work2much wrote:
Very clean install and looks like perfect use of roof space. What did you select for a charge controller? MPPT or PWM? Batteries type? Did you wire panels in series or parallel?

Any tips after a couple years of use?

I used a Blue Sky MPPT controller but have had a little trouble with it cycling between float and absorption. Which is odd because I have used them before with good results. For the small extra money you might as well go with MPPT. Definitely wire them in parallel, to reduce the effects of shading. I use Lifeline AGMs, properly cared for they will give you 10 years useful life.

Park in the sun :).

[HMS_Beagle]

bigfootford wrote:


I would not want to run my truck to charge the house batteries when Boondocking or camping if I do not have to... I run my little Honda 2000I...

As for the truck charging the camper house batteries most of our Alternators settle on a voltage output of 13.8 to 14.2... My solar will do 14.6-14.9 depending on the temperature of my camper battery..
To prove that I have seen my truck battery start to take a charge from the solar because the Solar voltage is higher than the camper... I know one can modify the truck charge system to over come that but I elect not to put diodes etc in the truck circuit to accomplish this. Diodes drop the voltage by .7 vdc...

Jim

I'm allergic to the sound of generators. I will hardly ever run my truck just to charge the batteries, but having it dump 50 amps into them when I run to the store or tour around does some good. The solar does a great job, but does it relatively slowly unless you have a large array. Slowly but relentlessly. If the batteries are down to 50 precent state of charge, the alternator will put 50 or more amps into them, even at 13.8 volts, while my solar will only put about 10 into them. When they aren't taking much from the 13.8V source, they are probably at 80 precent plus SOC. On a Ford you don't need any diodes, the charge source will be disconnected when the key is off. If you run a separate high amperage circuit, use the modern method of a voltage sensitive relay, no voltage drop.

[work2much]

Very clean install and looks like perfect use of roof space. What did you select for a charge controller? MPPT or PWM? Batteries type? Did you wire panels in series or parallel?

Any tips after a couple years of use?

[bigfootford]

HMS Beagle wrote:
I have operated the truck and camper for a couple of years without the charge wire connected. But I have found one or two occasions where I wanted it - several days parked under trees in heavy shade, cold temps so heater runs a bit. I had to move the truck into the sun for a few hours after 3 days. If you have upgraded the charge circuit to the camper, the alternator will charge flat batteries much faster than the solar (assuming a small array) for the initial bulk charge.

When I get around to it I will hook the charge circuit from the truck back up.

I would not want to run my truck to charge the house batteries when Boondocking or camping if I do not have to... I run my little Honda 2000I...

As for the truck charging the camper house batteries most of our Alternators settle on a voltage output of 13.8 to 14.2... My solar will do 14.6-14.9 depending on the temperature of my camper battery..
To prove that I have seen my truck battery start to take a charge from the solar because the Solar voltage is higher than the camper... I know one can modify the truck charge system to over come that but I elect not to put diodes etc in the truck circuit to accomplish this. Diodes drop the voltage by .7 vdc...

Jim

[HMS_Beagle]

I have operated the truck and camper for a couple of years without the charge wire connected. But I have found one or two occasions where I wanted it - several days parked under trees in heavy shade, cold temps so heater runs a bit. I had to move the truck into the sun for a few hours after 3 days. If you have upgraded the charge circuit to the camper, the alternator will charge flat batteries much faster than the solar (assuming a small array) for the initial bulk charge.

When I get around to it I will hook the charge circuit from the truck back up.

[bigfootford]

tuna fisher wrote:

bigfootford wrote:

HMS Beagle wrote:
An update: now driven a few hundred freeway miles, panels appear to be staying put without problems. 200 watts seems to be plenty - even after the heater is run a bit overnight, if it is sunny, by 10 AM all is charged full again. I have actually unhooked the charge cable from the truck (another story) and don't seem to have to worry about power in the camper at all! One of the more worthwhile mods for your camper....

Those extra watts of panels will be nice when the weather is overcast and harvest is way down and you still recover ah used!

I removed the fuse for the charge line in my truck instead of disconnecting the charge wire from the truck's charge system. Easy to put it back in if needed. Why would you disconnect or remove the fuse on your solar systym?

Jim

What was the question? If it was, "Why would you disconnect or remove the fuse on your solar system" then that should not be in my quote....

I do not remove the fuse from my solar system....

I remove the fuse in the truck for the trailer charge wire that is part of the truck harness.
My solar charges my house batteries better than the truck...
It is just my preference.
Some guys put a relay in there and switch the charge line for the camper as needed.
My Ford and many other trucks have the fuse and a factory relay... I just do not use that feature.

It appears that HMS Begale disconnected his charge wire from the truck to the camper. Says,"That's another story" and I could say the same thing and just removed the fuse.



Jim

[tuna_fisher]

bigfootford wrote:

HMS Beagle wrote:
An update: now driven a few hundred freeway miles, panels appear to be staying put without problems. 200 watts seems to be plenty - even after the heater is run a bit overnight, if it is sunny, by 10 AM all is charged full again. I have actually unhooked the charge cable from the truck (another story) and don't seem to have to worry about power in the camper at all! One of the more worthwhile mods for your camper....

Those extra watts of panels will be nice when the weather is overcast and harvest is way down and you still recover ah used!

I removed the fuse for the charge line in my truck instead of disconnecting the charge wire from the truck's charge system. Easy to put it back in if needed. Why would you disconnect or remove the fuse on your solar systym?

Jim

[Terrick_down_Un]

HMS, thanks for the update, I have been collecting info to do my panel install. Unfortunately I have a rubber roof, so will be using screws as well as adhesive.

[HMS_Beagle]

There have been a couple of new questions on Bigfoot and solar, so I thought I would bump and update this thread. The install was completed in July 2014, solar panels are still in place today with no sign of them coming loose. I don't think you could use the same installation method on a less solid roof (rubber or sheet aluminum) but it works will on a solid fiberglass roof.