How to mount Solar Panel to roof of CT?

[subterran]

Hello! I am new to this forum, and found it looking for info on my own conversion design. I just bought a used Haulmark 6x10. It already has windows and an insulated roof with a thin whiteboard liner, so I can't see any of the roof trussing. I have figured out by the screws inside that the ribs are on 24" center which is perfect for my panel.

My question is - the roof is seamless, and seems to 'float' un attached to the trusses. Is it going to be OK for me to just punch a bolt hole all the way through the truss and roof from below (a small one with washers) to bolt it down with, and seal it well with silicone?

Perhaps I should add that I just noticed after some pretty bad weather that the center vent leaks a few drops. It is pretty UV damaged, and I want to replace it with a self-powered unit, so at some point soon I am going to need to peel off the thick weatherproofing goop, and replace the whole shebang.

Thanks for your thoughts!

[woytovich]

WHen you pull out the roof vent you will be able to see what is going on with the "floating" roof. I suspect that you will be able to do as you suggest in attaching your panels to the roof... I'm sure there are other concerns regarding the solar panels such as protecting them from damage both from falling/flying debris and from flexing during travel but others may know more about that.

Take pictures and share them here when you get going.

Mark

[GPW]

Sub , you may Not want to mount your solar panels on the roof ... I just carry mine (in the original box) and set them up when and where needed... No worries of damage ...Easy to do ... No holes in your roof ...

[woytovich]

Sub , you may Not want to mount your solar panels on the roof ... I just carry mine (in the original box) and set them up when and where needed... No worries of damage ...Easy to do ... No holes in your roof ...

...and with a long cable you can position them as needed. As someone here pointed out you might want to park the trailer out of the midday sun and that is exactly where the panels should be.

[subterran]

Thanks guys!
I will post pics as I get going...got alot of stuff coming in this week for the project.

I have other motives for putting the panel(s) up there actually, and I intend to mount them on 4 hinges with removeable pins, so I can tilt or remove them. They already have the MC4 connectors, so I can unplug them at the panel.

My trailer is stored in a secure parking lot, in pretty much full sun. While it is parked, I intend to use it as a solar generator, to keep another set of batteries charged that I will be using.

I run an internet radio station as a side hobby, and it has been my dream for years to make the station completely run 'off the grid', so this is how I'll do it! The batteries running the netbook that I use for the station will run for over a week with no recharge, so I can take the trailer out whenever we need to.

I intend to get my moneys worth for the investment!

[jwhite]

I would like to know more about useing solar panels to charge batteries,I was doing some reading last year but decided to wait a while.
I didn't use my trailer much last year so I was takeing the batteries out and chargeing them before a trip but that got old fast so
I bought a diamond plated tool box and I am going to put my 2 deep cycle batteries in that and place it on the tounge of the trailer so I can charge them there with a old school trickle charger I have and use.
I have a honda generator I use to charge my golf cart and run any electrical things I need but it would be nice to not have to also run the charger on the batteries if I can charge them with a solar panel.
I had thought about putting the solar panel on the roof rack of my suburban but I think that just haveing it so I can place it to face the sun while I am useing the trailer is all I need.

[pete42]

Thanks guys! (snip)
I run an internet radio station as a side hobby, and it has been my dream for years to make the station completely run 'off the grid'

I'm listening to live365.com right now.

good luck with panels.

pete

[subterran]

jwhite:

It sounds like you have plenty of time to charge your battery, plus you have a generator you can use to keep it charged when you are using it alot. So it sounds like you can do with a small panel and charge controller.

Basic Solar systems are fairly simple: You have a panel that runs to a charge controller, and from the controller to the battery.

The charge controller keeps the panel from overcharging and destroying the battery, which is what would happen if you hooked it straight to the battery.

Have a look at these items:
Solar Panel:
http://www.amazon.com/HQRP-Flexible-Mon ... 721&sr=1-1

This solar panel outputs about the same as a 2.5 amp charger in full sun (give or take a fraction) It is semi flexible, and very thin and so very easy to mount, or move, or whatever. If you wanted to mount it to your rack, you could mount it to a bit of plywood. My point is: it's very versatile! You can also chain them together if you need more power.

charge controller (cheap, and with no 'load' connection, but it will work!):
http://www.amazon.com/Sunforce-7-Amp-Ch ... d_sim_ol_1

This system will work fine if you have several days of good sun to recharge and top off your battery.

My system, as I was saying above, needs to support an electrical load 24/7, so my panel and controller are larger.

Now, getting a bit more technical: the simple controller I linked above only has connections for "Panel" and "Battery", where most controllers also have a "load" connection as well. What this is for is to connect to a fusebox (suggested) then to the devices that you want to run. (except for high-drain devices, like a big inverter - you would just connect the big inverter directly to the battery) The reason is that the 'Load' connection also regulates the voltage going to your devices to keep it steady, whereas the cheap one above will be outputting up to 14.5 volts when the sun is out. Most 12v devices can handle voltages from about 11.3 up to 15v without problems, but some cannot. If you worry about such things, then go for a better controller, like this one:
http://www.amazon.com/HQRP-Controller-D ... 652&sr=1-1

...and connect your fusebox/devices to the 'load' connector.

Last little bit: Solar panels put out a good bit more than 12v. That is why you would generally never want to hook anything up to one directly. The charge controller focuses this extra voltage into just the right voltage and amperage to charge you battery, and monitors the battery voltage to keep it from overcharging.

[woytovich]

You wrote:


"If you worry about such things, then go for a better controller, like this one ...and connect your fusebox/devices to the 'load' connector. "


With this controller would you hook the battery to a battery connection and a fusebox to the load connection or is the battery on the load connection also?

Is the problem with the first controller that if you are in the sun with the panel connected to the battery and then loads connected to the battery that there are potential overvoltage problems to the devices?

[subterran]

Q:"With this controller would you hook the battery to a battery connection and a fusebox to the load connection or is the battery on the load connection also?"

A:Yes, what you said. Hook the battery to 'battery', and load to 'load'. No battery on the load side! On the load side, you would be wise to connect it in this way: 'load' connection > fusebox > device(s)> That said, most 12v devices have fuses in the plug-end anyway.

Q:"Is the problem with the first controller that if you are in the sun with the panel connected to the battery and then loads connected to the battery that there are potential overvoltage problems to the devices?"

A: Exactly right. Any device connected to the battery while the sun is shining will recieve the maximum output voltage of the charge controller. In this case, the cheap charge controller will turn on (start solar charging) at 13v, and anything connected to the battery will see the charge voltage, which is about 14.5 (or so) volts. When the battery reaches 14.2 volts, the charger cuts off. As I said above, most devices are meant to work in a car, where voltages can vary wildly, and so can handle a fair range of voltages.

[woytovich]

Got it... thanks... seems the extra <$20 is a good investment.

[subterran]

I agree - but I did want to point that out to anyone who may use this thread going forward, or to someone who is ONLY charging and will disconnect the solar before using.

There is actually a third option in controllers, but you only realize the advanges of them if the panels are stationary. These are MPPT controllers, or Maximum Power Point Tracking. These are pretty pricy, and do not really have a use in our circumstances, but if you were installing for a cabin or home, it would be a worthwhile investment.

Read more here:
http://www.windsun.com/ChargeControls/MPPT.htm

[jwhite]

Thanks for this reply I was hopeing that someone that has already done there homework would reccomend what I need and where to buy it.
I think the larger controller is the way to go if I were to add another panel.
my 12volt use is minimal I have a older deep cycle battery that has went dead because something was left on and killed it.
So I have my water pump and lights on that one and I don't use the water pump or lights much,I burn alot of candles and my TV gives off alot of light also.
the other battery runs my marine cd/dvd player so I was hopeing I could go for a few days without haveing to charge my batteries?
My tool box is coming in today so I will be moving the batteries outside onto the tounge.
I may go ahead and buy the solar panel and controller,I am going on a 10 day trip in a month so I want everthing ready.

[subterran]

Glad to be some help.

One last thing: you should always put your charge controller as close to your battery as possible. They are temperature compensated, so if the controller is inside your CT, and the batteries are outside in the cold / heat, bad things will happen!

[bdosborn]

Thanks for this reply I was hopeing that someone that has already done there homework would reccomend what I need and where to buy it.

PV panels on Amazon are expensive for the output and the controllers are of sketchy quality. Do a search on eBay for 80 watt solar panels, that seems to be the commodity size. ul-solar and serpentlion2008 have good panels for low prices. The output is as good as my top of the line Kyoceraand the build quality isn't far behind either. Sun Electronics has a great price right now on an Sun 85w panel The 85 watt panel would likely keep up with all your electrical needs, it did for me in our Tear.

Morningstar has pro quality solar controllers for only a little more than the Amazon stuff. I would look at a Sunsaver 6 or 10, depending on the size of you panel. Morningstar publishes good installation guides as well as detailed specifications, which is often lacking with cheaper controllers. I have a Sunsaver MPPT controller and I agree, it's probably not worth the investment for a small, single panel system. Prices vary, do a Google shopping search for a good price on controllers. EBay doesn't seem to have good prices for controllers anymore.

Morningstar Sunsaver

PV systems can run from mild to wild but you do need to do some homework to avoid the ready-shoot-aim syndrome. The first and most important step is to try and get a handle on what you think your energy usage will be. Here's a link to a site that can help you size your system.

Solar Design Worksheet

Bruce

P.S. Here's a link to my PV setup:Boxcar Solar