Best attachment and set-up for solar panels

[DuneElliot]

I am just getting ready to install 4 100w solar panels from Renogy. I have the sealant from Dicor for the holes.

The roof is EPDM and, I'm guessing, plywood underneath.

I've done some research about the best attachment method and after reading about several (more than 10) personal installations in a similar roof, screws (not well-nuts) seem to be the way to go. (Several people reported well-nuts loosening on wood roofs).

With this in mind, what kind of screws are best for this set-up? Would a coarse thread, wood screw be appropriate? It also seems that the thicker the better. What are people's thoughts on this?

Also, am I am better off hooking them up in series or parallel? I was looking at doing series/parallel. My charge controller is a 40A MPPT controller. Will all set-ups work?

[Ed ke6bnl]

what i did was to attach unistrut to the roof with stainless steel screws and then attach the solar panel to the unistrut. panels can be removed with not work to the roof. worked great for me because where I attached the panel the roof had some curvature.

[Yarome]

Yup. Coarse stainless steel wood screws and as large as your mounting brackets will allow to avoid any "Play". 

I don't recall exactly how long your 5er is or what your roof layout is like, but if you can run dual series/parallel without any shading issues on either array then that would be ideal. The main issue being that any shading on either panel in a series array will affect the production of the entire array. Not just that single panel. One other advantage is shorter wire runs. The series connections should be of equal length in both arrays and then equal length parallel runs to your c-box (if you're going through the roof) vs. equal length parallel runs from each panel. You just need to ensure your controller is good to go with 24V.

What brackets are you using and what type of roof/panel gap are you planning on? As Ed mentioned.. you need to be aware of any roof curvature to ensure they are mounted level.

Kind of spendy, but I had a curvature issue and used these. With the wing bolts it also makes it simple to dismount the panels for cleaning the roof, or adding in tilt bars to one side or the other.

[DuneElliot]

RV is 27ft long and planning on mounting them at the front. The only thing there is the vent cover. I can't check the best place for them as it will not be here until the weekend...running out of time as the house closes on the 4th.

I am planning on using the brackets they sent me as part of the system.

 

The charge controller automatically detects 12/24V, according to the website

[Yarome]

Who did you get your system through?

Congratulations on your closing, BTW... Big steps, hu. 

[DuneElliot]

Renogy, direct from them. I still have to order connectors as I didn't want to do much without knowing my set up.

[Sehc]

Renogy mounting feet seem ok. I mounted to uni-strut to compensate for the curve of the roof top. I was able to through bolt my strut with 2 1/2 inch bolts. There are many self drilling and self taping screws that will hold well in plywood. Even galvanized deck screws. Be careful with stainless. They are easy to twist-off or break.

[DuneElliot]

Thanks. That sounds about the kind of information I need. I don't have much of a curve in my roof as the bedroom area over the hitch is one of the low-ceiling types.

[Yarome]

With plywood.. to avoid any potential splintering under your roof covering (that could lead to wear points and cracks) it's best to avoid the self-tapping and pre-drill your holes.

[Jack Mayer]

On 7/19/2017 at 4:02 PM, Yarome said:

With plywood.. to avoid any potential splintering under your roof covering (that could lead to wear points and cracks) it's best to avoid the self-tapping and pre-drill your holes.

I agree. I usually use short #10 or #12 stainless and pre drill. Make sure not to drill the hole too large....Cover it with Dicor, and use Dicor under any aluminum "feet" for extra holding power.

[oldjohnt]

Yarome, while I love using "self drillers" in aluminum or sheet metal, FWIW I agree they are NOT best in plywood because 1) The drill size diameter (even though good for metal) is just too big for that soft wood application. If your self drilled pilot hole is quite a bit smaller then you get more of a thread surface bite into the wood. 2) The typical sheet metal self drillers just don't have as aggressive and deep thread as some wood screw do.

Actually in soft wood with the right screw I often get by with no pilot hole at all or just a light punch to get the screw correctly centered and started, then let your cordless driver do its thing 

 I cant count how many self drillers are in my RV lol but they are sure easy to work with

John T  NOT a Carpenter but love them self drillers in the right places

[Yarome]

It looks like those renogy brackets have some type of adhesive on the foot. I would peel those off, then as Jack said... shoot some dicor into your predrilled holes and a generous amount where your bracket foot will sit. It will give you better roof contact, more adhesion and a much more reliable water seal. Use a wetted finger to evenly distribute any dicor excess around the foot itself. Once the "setting" dicor is firm (not necessarily dried/cured) you can go back over and seal the feet and screw heads. Don't skimp on the dicor! You may need to go back over the screw heads and feet one last time after the initial application has levelled and set.

Truth that, John. Self tappers DO have their place, but it ain't in wood. Even plywood is still somewhat "alive"... constantly expanding and contracting. Without those deep course threads you really have no holding power... especially in such a short screw. One dry cold spell and those fine threaded screws will lift right out with your fingers.

[Sehc]

Do not use fine threaded screws. They are not meant for wood. Use the course threaded ones that say "wood" on the packaging. The Renogy angle bracket feet i received from Renogy don't have sticky tape on their base.

[DuneElliot]

Thanks guys. I will pick up some 1" coarse-thread wood screws and drill some pilot holes. I have both leveling lap sealant for the holes and under the panel and non-leveling sealant to completely smother the feet and screws when everything is mounted. I also have Eternabond tape to secure the wiring to the roof between the panels and wherever the wires go into the roof and down to the battery compartment.

I just learned yesterday that my friend will be letting me park at and stay on her place until mid-September so I now have a little breathing room for getting this done as I will have electric and water while there.

[Yarome]

22 minutes ago, DuneElliot said:

I will pick up some 1" coarse-thread wood screws...

Just to be aware. More than likely your roof ply is only 3/8". Possibly 1/2", but I doubt it. I probably wouldn't go any longer than a 5/8" screw. If you were shooting to hit the roof trusses, that would be a different matter, but just ply... you wanna leave some material at the tip of your screw for the best hold.

I'm not sure how large the holes are on the renogy brackets, but remember you always have the option of enlarging them to get a decent size screw in. Just from a photo they look to be a little anemic.

[DuneElliot]

Okay, Yarome, thanks. 

The hole sizes on the brackets are pretty decent so I will take them with me and get as large as I can

 

[jimnina]

Hey Dune

You should be very happy with the Renogy setup. I only needed a single 100W panel and it has worked very well for over a year. We used it to keep the 4-12V batteries charged while it was in storage. Since I only had a single panel I used a a ladder bicycle rack to hold the panel. Since we have had roof leak issues I was told by the boss, no holes in the roof 

[Eric A.]

I installed the Renogy 400w kit on my little Jayco last year. I'll be installing their larger 600-800w kit on the 5r.  I used pole barn roofing screws to hold down my z-brackets.  They are coarse threaded and have a small rubber washer below the head to help seal out water.  I planned out my mounting area and put down a piece of Eternabond just slightly longer than my foot everywhere one would sit on roof.  Then I predrilled holes, small dab of Dicor on screw threads, and mounted foot right on top of Eternabond.  Once everything was mounted and hooked up I completely covered screws and feet with self leveling Dicor.  I then did like you said and Eternabond covered wires all the way to access area in roof.

You will love this kit.  It's served me well over the last year and it's awesome not needing a plug in to keep batteries up to boondock!

[DuneElliot]

Panels are installed, as of this morning. Now I just have to figure out how to wire them all together and go to the charge controller. It's all a little overwhelming, but one step at a time.

[Eric A.]

Slow and easy, double check everything.  It's really simple if you follow the instructions.  Just scary because your always afraid your going to fry thousands of dollars of equipment! 

If they didn't include 30 amp inline fuses in your kit (they didn't in mine) get some.  One between the panels positive wire and controller and one between batteries positive wire and controller.  It's worth the extra $10 or so bucks to protect your investment.

[pethier]

interested

[Sehc]

Fuses are there to protect the wires. With the renogy 100 watt panels follow their instructions. Each fuse introduces more voltage drop. You should only need a fuse at the positive battery connection. If you connect the four panels in parallel you need a fuse on each panel. That is to prevent a short in one panel pulling the other three panel outputs into the bad panel. Not needed if series/parallel. Throw a blanket or cover on the panels when making connections.

[DuneElliot]

I used the 10A fuse provided between the panels and the charge controller, and the 40A fuse they provided between the charge controller and the batteries although this isn't all hooked up yet.

 

[Yarome]

18 hours ago, Sehc said:

If you connect the four panels in parallel you need a fuse on each panel. 

 

33 minutes ago, DuneElliot said:

I used the 10A fuse provided 

Getting in to fusing individual panels can lead to some interesting and in depth discussion. In very limited circumstances they can have their uses. Say.. in the event of an external short with a particular panel, however, that also depends on the overall size of the array/arrays, wire ratings, controller built in protections, etc.

Interal shorts are, for the greater majority of newer panels, if not nearly all, on the market today (as ARE the renogy's), a moot point since they are equipped with bipass diodes. Basically... one way trap doors that won't allow panel backfeeds making the purpose of installing them for panel protection and/or loss of production across the entire array/arrays obsolete.

IMHO, with many RV mounted solar arrays being very limited in current capacity (NOTE: I do not say ALL), fusing individual panels is an unnecessary over-precaution at the expense of solar production.

My recommendation in DuneElliots case... DUMP the 10amp fuses. The 40amp at your battery is sufficient, although, I WOULD recommend a panel disconnect leading in to your controller.

[DuneElliot]

The 10A fuse was provided as part of the set-up and complete package from Renogy. I would surmise that if I didn't use it and something happened my warranty would be void. It is only one fuse and is inline at the panel end after the MC4 connector and before the lines going into the roof.