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Solar Install Roof Access Question


Daveh

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So my Lifepo4 Solar install will be happening over the next 3-4 weeks. I have done a lot of research and this board has been incredibly helpful. Even though this part of the install is a few weeks away I am particularly concerned and obssessed with the wiring drop from the roof to controller. The unit comes with a preinstalled 10 gauge run that is poorly located in relation to batteries and planned controller site. I looked at this link and found it helpful. http://www.rvnetwork.com/index.php?showtopic=108331&hl=%2Broof+%2Bdrilling#entry663669 I am going to give my vents a very careful look but the fridge vents to the side and the other two are located better than the preinstalled solar run but still are less than ideal. My ideal location would take me right from the roof into the closet directly above the controller and battery installation location. This is an EPDM roof. I sure would like some insight from someone experienced with them. Should I drill up or down? Should I first cut with a utility knife and then drill? Should I gradually increase the size of the hole? Use a hole saw? I will put a hole in the bottom the combiner box. Should I also have a pvc conduit going down? Should I put down dicor--then box--then some screws--then seal again? For some reason the riskassociated with lifepo4 and inverter install is acceptable but this looms over me? Yes I have read all of Jack's stuff and the install will follow his recommendations along with Bill Joyce, Reed and others on Lifepo4--againI thank you...... I anticipate using 3 or 4 gauge for the drop to the controller and will have 700 ah batteries. Dave Extra thought. Jack is there any plans for another install get together this calendar year for solar?

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In our installation Solar System, we drilled from the roof down wanting to have the hole in the middle of a wall space that ran from the roof to the floor just about where the solar controller would be. We used the batwing antenna base as a reference point and measured the offset for the hole at least 30 times.

 

When we drilled the hole through the roof, we found that about 6" down there was a header across the wall and the hole saw I was using couldn't reach that far in. I was running a dual #6 wire which the 1.25" hole I drilled was enough. You are planning much bigger wire. Make sure you have a way of cutting the hole a distance the thickness of the rood system.

 

I glued the combiner box with 3M 5200, virtually permanent. I also caulked the edge with Dicor.

 

The wall I used was the "conduit" I used. The drop wires to the controller and the RJ45 cables that ran from the solar controller to the remote panel mounted in the same wall.

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Dave, there are lots of ways to proceed. If you want to contact me by email I'll Be Happy to have a discussion.

 

No plans for a solar install rally this winter.....yet. We thought we would be out West all winter, but as of the moment it looks like we will be at Tampa again for the January show. With a big twist on the show this year (more on that later). A solar rally is possible and I'd again act as a technical consultant and review plans and help with designs. That assumes we actually do go to Tampa. But it will remain for someone to plan it. Jim???

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Dave, don't you hate the idea of drilling through an EPDM roof grrrrrrrrrrrr I ran my solar wiring down through the rooftop fridge vent as it has a raised sealed metal enclosure plus a cover over all the top. If I just had to drill the roof I would size the hole for a tight fit and use PVC conduit with a 180 loop/bend at the top and use a premium sealant and then let dry and re seal all over again.

 

You didn't mention your total solar watts and at what voltage (series or parallel or what) you're operating. Of course you need to know all that to compute the max and typical current from rooftop down to the controller plus the length of the run to accurately calculate the wire size. AND WHEN DONE BUMP IT UP A SIZE OR TWO FOR ADDED MEASURE AND EXPANSION LOL Bigger wire = less voltage drop,,,,,,,,,,,less I Squared R heat loss,,,,,,,,,,,,,,,more room for expansion. Up top I used those sealing type connectors then then coated silicone over all for extra measure.

 

I would really enjoy a Solar Seminar myself and may be able to contribute something. Though long retired from the practice, I still love "tricity" I'm in Florida much of the winter but usually booked up with Bluegrass Festivals and Antique Tractor shows where I sometimes give Tractor Electrical Seminars and Workshops.

 

Keep us posted

 

John T

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Confronted with same quandary, I worked from the inside out. I was concerned that if I drilled from the roof down, and with my luck, I would hit a stud dead center or some other obstacle such as wiring or an AC duct. What I did was go from the inside of a closet about where I wanted the wire to run, measuring carefully to make sure that the combiner box would be positioned away from any roof obstacles and then made about a 1 inch hole in the ceiling of the closet so I could check that the coast was clear for a hole. Once it was established that everything was OK I drilled up through the roof with a 1/4" drill bit then went up on the roof and located the hole. I enlarged the hole for the 4 gauge wires I was running and Dicored the combiner box down. The fact that Eternabond tape will make permanent repairs to the roof membrane took much of the angst out of the process.

 

Good luck

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I just completed my installation and had many of the same factors affecting the installation. I chose to drill from the roof down into a closet. After measuring many times, I drilled a 11/4 hole using a spade bit. I used a very sharp fit and started slow. Once the membrane was penetrated, then drill speed was increased. Combiner box was mounted on the roof with screws and Dicor. Don't forget to block the hole so Dicor doesnt flow down into closet. Wire from panels to combiner box is 10ga that is held in place with puddles of dicor. 4ga wire from combiner box to solar controller was not in conduit, but was secured at regular intervals and "rub" protection installed at any point where friction/rubbing might occur.

 

I agree about holes in the roof, but felt i needed the most direct/shortest route for the wire. Good luck on the install. I enjoy a beverage and watching the meter show +amps now that the project is complete.

 

By the way, Jack and Bob Shearer were extremely helpful throughout.

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How you do it is somewhat installation specific. There are many "right ways".....

 

I first determine if there is any framing member where I want to penetrate. This is done two ways...first use a studfinder. Next, if it seems clear then drill a "small" hole from the roof or inside. Again - installation specific. If you are trying to work into a corner or side of a cabinet or closet then from the inside out. If trying to penetrate into a tight area or a very open are then outside in....it just depends on how your routing goes.

 

Once you do the "discovery" drill - I usually use a 1/8" bit, followed by a 1/4" bit - then you can determine that there is freedom to do the "big hole". Usually this is 1.25" to make it easy to route things. Again, this may vary depending on requirements. I drill this with a holesaw. I then put in a piece of appropriately sized conduit. (Use the appropriately oversized hole saw for the conduit size.) This conduit sticks about 1/2-3/4" above the roof deck and is secured with caulk and pressure fit. The purpose in having it above the roofline is to prevent water infiltration IF your box fills with water. It should not - but better safe than sorry. The purpose of the conduit is roof penetration only. I don't usually run the wire in conduit. But sometimes the conduit continues to the basement if it is a straight shot.

 

The distribution box sits directly over the conduit and is simply caulked down. No screws at all. The size is again installation dependent. It has to hold the appropriate hardware. But I never use less than a 6x6 plastic utility box that is waterproof. This will route the cables for the solar, as well as (perhaps) antenna cables and cat5 outdoor cable.

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I like to drill a 1/8 hole then grab a small L shaped allen wrench and poke the short end through the hole. You can then spin it around and see if there is anything that would prevent you from drilling a 1 inch hole.

 

If you tend to drop things grabbing the long end of the allen wrench with a visegrip or the like will save you from having to replace it.

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