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Topic: Roof Solar Panel Installation---Done (Read 1139 times) previous topic - next topic

Roof Solar Panel Installation---Done

Our Solar installation is finally done. This has been a long process, trying to make it as "factory" as possible as well as giving full roof access for walking without stepping on a panel or falling off.

So, we have four commercial Yingli 285 watt, 36 volt panels up top. They are 6.5 feet tall and quite wide too. Yingli is a top manufacturer of commercial panels with an 80,000 panel installation just completed by company the guy I bought them from works from. They have installed a total of just over 500,000 in the U.S.  I got the lowest wholesaler discount possible at $170 each. So, the total for the panels was $680 out the door. See the Yingli panels at: YGE-U 72 Cell Series | Yingli Solar  Panels are mounted about 2" above the roof to allow air circulation underneath. The cooler the panels are, the more juice they make.

I did a series/parallel installation so I have about 72 VDC going down through the roof. I used commercial connectors and wires and where exposed, used vinyl flexible conduit to protect the wires from the sun, stepping on them etc. A stud finder on the metal setting was used to locate the aluminum frame just under the glass skin.

Larger panels must be higher voltage as the wires would have to be very large to do the job at 12V. With higher voltage, a MPPT controller is mandatory as the Classic 150 takes any voltage up to 150VDC and converts it to what our 12V Foretravels need.

The controller is a MidNite Classic 150 MPPT from Northern Arizona Wind and Sun @ $610 plus $12 shipping. It is the only controller that will handle the 1140 watts. I also used MidNite's mini box for the 12V breakers for the PV panels and also between the controller and the batteries. It has a maximum of 150 volts input but on a cold morning, the panels if wired in series, could easily exceed the 150 volts. The controller is protected but will not switch on until the voltage drops to 150V. I used the top can compartment to mount the controller and all wiring. Hardie backerboard was used to make the inside as fire resistive as possible.

I brought up a pair of 4/0 cables from a junction box below the fridge where the hifi amplifiers will go. From there, a couple of 2/0 cables lead to the electrical box below. A 250 amp fuse was installed where it connects to 12V. The compartment will also be lined with Hardie board as the amps are installed.

When we bought the coach, I found a real deal on 6 Genesis EX70X sealed batteries. They can just sit on a shelf for 2 years and still have 12.7 volts. They work well as house batteries. Actually, I bought extras and installed them on a couple of cars. As you can see from the site, they are VERY expensive but many solar companies go out of business as fast as they open and I got them for $35/each. http://www.osibatteries.com/p-997-enersys-genesis-pure-lead-xe70x-0771-6003-battery-68ah-w-metal-jacket.aspx

How does it work? Great! Before the sun even comes up, the cells are sending 72 volts to the controller. Once the amps go up a little (sun not up yet), the controller switches on and it starts to charge. In the photo below, the controller has just switched on and is starting to charge the batteries. As it does this, the voltage drops a bit. With the sun up, the voltage runs from 70 to 80, depending on the outside temp and the watts also head up depending on how high the sun is and what level of discharge the batteries are in.

The controller is both very complex and very easy to set up when installed. The default setting are designed to not damage any make of battery with exact changes easily done from the menu. Just set the date and time plus lat/long and it knows when the sun rises and sets. All voltages are settable, even the LED reading can be made to reflect the exact voltage at the batteries from a good digital meter.

So, about $1600 out the door plus a lot of time gives you the potential of 1140 watts in ideal conditions.

The MidNite controller has ports for a Mac or PC display/control and can be assigned an IP number so you can see how it is working any where in the world with internet access. See info at: MidNite Solar Classic Charge Controllers and Clippers

RVs are eligible for second home tax advantages so any installation times 30% can be taken directly off income taxes you owe.

Please let me know if interested in a like installation information.

Pierce

Re: Roof Solar Panel Installation---Done

Reply #1 –
Awesome job Pierce!

Re: Roof Solar Panel Installation---Done

Reply #2 –
Looks great Pierce. Many questions to come once I decide to go solar!

see ya
ken

Re: Roof Solar Panel Installation---Done

Reply #3 –
Thanks Don/Ken. I'm sure when you got into your bulkhead/basement project/hydraulic pump, you never expected it to be so complex. Same here with almost everything to do with solar. Every forum has different opinions on panels, controllers, connectors, wires sizes, this vs that, etc.  So much in the planning part of it so you don't kick yourself after it's all done. And just when you think you have a handle on it...

Pierce

Re: Roof Solar Panel Installation---Done

Reply #4 –
The technology is changing so fast. That MPPT controller you got seems like just the ticket. I think I'm going that direction even though I'll have about half the total power (also in 36vdc).

How did you prep the fiberglass roof for the 3M high-adhesive tape? I finally got all the useless crap off my roof (broken storage box and 1990s satellite dish) and have plenty of room for the panels. I need to get a handle on this.

Great job, by the way. I was amazed at the charging voltage going up so quickly. MPPT rocks.

Craig

Re: Roof Solar Panel Installation---Done

Reply #5 –
Craig,

I wanted to be able to pull the panels off so I drilled into the aluminum roof frame material. I used a HF stud locator with the "metal" selected and then drilled and screwed them down. They are secure but I will use an expanding fastener as soon as they arrive. I also want to use an Allen button head stainless to make them more theft resistive and screw it down into the expanded fastener fitting.

I did discover a new tool for removing all the old and very useless roof coating put in every possible spot. Harbor Freight sells it as a: 6 Piece Pneumatic Scraper Kit  . It was on sale for $16 so I gave it a try. I just vibrates and even if you push the blade against your hand, it does not do much. I put a little edge on the blade  and gave it a try. Moderate pressure on the thick stuff takes it  off quicker than anything else I have tried. I just vibrates a little and the nasty stuff peels off. Not as good for the thin edges but have had luck with a sharp scraper,  3M pad and Comet. The big surprise was the amount of dirt underneath. Small cracks must have let water and dirt in as it was clear that the coating was only cosmetic.

I called MidNite today and described the full voltage (but no amps) before the sun came up. He said that with a full moon, the panels will generate enough voltage to show on the panel. No amperage naturally.

They have been working on a work around to directly go to a laptop with an easy connection. Now, you have to go to your laptop prefs, select the local LAN and enter an IP of 192.168.1.13 and then navigate to the NET menu and enter 192.168.1.14 and then just plug in. The problem comes when a customer goes home or to a hotel with ethernet and it won't connect. You have to change it back to the original setting which you have forgotten. MidNite then gets calls from customers. They want you to use a router instead but if you don't have one in the RV, you have to use the more difficult choice.

MidNite said there is no reason to shut down the system while driving, plugged into shore power or with the generator running. It will just see a higher voltage and probably go into "float" mode.

Pierce

Re: Roof Solar Panel Installation---Done

Reply #6 –
Voltage with a full moon! That's cool!

My plans are to simply tape the mounts down but the roof is so oxidized that I'll have to clear that off. Yet I don't want to "wax" it either. Or do anything else to interfere with the tape-to-roof bond. Not sure, yet how I'll address that.

Plus we had a storm go through here with some roof damage to the StixNBrix which we'll have to repair. Before winter and rain. We only get 8" a year but fall will bring a fair bit of that. It never ends.

Craig

Re: Roof Solar Panel Installation---Done

Reply #7 –
Craig,

Sure that the "magic" tape will do the job, especially on a smaller panel. Since these are 6 and a half feet tall, I just was a little worried about one flying off and through a school bus windshield. Actually, the tape is probably the strongest way. Just don't want to be paranoid in a big blow.

We were in Canada with the old RV when a mini twister hit us. It was windy but this one took us off the road, ripped a bathroom roof vent that was closed right off our RV. Tore off the engine access cover too. Never saw it coming.

After drilling down through the roof for the mounts and wiring (1 1/2" hole), the roof is about .400 inches thick with a layer of glass on top and then wood before you get to the much thicker foam.  Seems well bonded together and I never had the feeling of any weak spots while up there. The cracks I have seen in other rigs must have had some kind of delamination first before the cracks started. Could have been a poor bond at the factory or more likely, the wood got wet and dry rot developed. The fiberglas may have expanded and contracted at a different rate in those spots causing cracks to start. Noticed three cracks in a 1989 U280 that were on the passenger's side toward the rear and visible from the ground. They curled upward indicating they had separated from the wood below.

Pierce

Re: Roof Solar Panel Installation---Done

Reply #8 –
Pierce, absolutely amazing. When I get my rig I will be picking your brain on this one. I was wondering if you were going to start selling electricity  like a power plant to neighboring rigs :)) :)) .

The knowledge base here is absolutely priceless.

Larry

Re: Roof Solar Panel Installation---Done

Reply #9 –
Quote from: Pierce & Gaylie Stewart –
The problem comes when a customer goes home or to a hotel with ethernet and it won't connect. You have to change it back to the original setting which you have forgotten. MidNite then gets calls from customers. They want you to use a router instead but if you don't have one in the RV, you have to use the more difficult choice.

You can use an "access point" in the RV if you don't want a WiFi router (or you are using a cell system router). An AP is like a WiFi "hub" in that it doesn't route but connects devices to the network. They can be set to assign IP addresses via DHCP if you need that, or not if your cell system router does that. I use one AP in our house because the WiFi-enabled DSL router in the kitchen is too far from the bedroom for my tablet. So we have "lakehouse" and "lakehouse2" and the smartphones and tablets just connect to the one with the best signal.

Access points also can conveniently add wireless capability to a wired coach or house network. So you could, for instance, just run a CAT5 cable to the coach between the bedroom and the salon where the closets and storage make it easy and install an AP at one end. This way you can put devices into the coach which do not have WiFi capability and just connect them to the CAT5 system where they'll become members of your LAN and wireless devices can reach them, too.

If you set up the DHCP (IP address assignment system) to use your Internet wireless router everything on the LAN will have access to the Interwebz and you can probably check your solar controller with your smart phone. :)

Craig

Re: Roof Solar Panel Installation---Done

Reply #10 –
We also used an electronic stud finder to locate metal roof cross braces, drilled pilot holes and used screws to fasten solar panels down.

Our Morningstar solar controller also has Ethernet connectivity and we found that a router is a valuable tool to have in our motorhome. New Cradlepoint routers are not overly expensive, can connect to WiFi (& cellular), offer firewall protection, create a secure hotspot, all without having to change our device IP addresses. We can control our solar system from our computer.

We find that when multiple charging sources, like alternator, Xantrex & solar are on at the same time, the highest voltage source will fool the others into thinking the higher voltage is coming from battery. All battery chargers use 'battery' voltage to know when to turn off or go to float. A discharged battery may take a long time to be replenished, even though a high-amperage charger is available, but it is in float mode. It all depends on what the charge voltage is set at from each device. We found it more practical to set our solar charge voltage high to improve solar charging and turn off solar controller when charging from shore-power Xantrex.

Our solar and Xantrex chargers have battery temperature compensation, so hot batteries will not be 'damaged'. But our alternator is not temperature compensated, so we have our alternator's variable voltage regulator set low to not 'damage' hot batteries. We figure that the alternator's job is to supply current while driving and replenish starting current, not to be a major battery charger.

Re: Roof Solar Panel Installation---Done

Reply #11 –
Great idea Craig! Will probably use another WiFi router as we don't get cell anywhere in our area so just prepay with AT&T on our iPhone. I found a new AT&T DSL router that fell off the truck (actually did fall off the truck) on a local road so can rig that up. Probably can use a DC supply to power it. Does that sound reasonable?

 Have to think about a true sine wave inverter now for efficiency plus hate to wait three times as long for the microwave to work. With tent campers next door in some NPs, don't like to start the generator for the MW. Have a small Brother laser printer that likes sine wave too.

Thanks for the idea.

Barry,

Just read your post as I hit reply. Thanks for the tips. I have run out of time as we are leaving in a few hours so have not run the temp probe yet to the batteries (6).

Pierce