Solar Panel Replacement / Update

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Isaac-1

Isaac-1

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May 10, 2010
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SW Louisiana
Well it is starting to look like we will not be moving after all, so since last year it was new roof time, this year it is time for new solar panels. I have not decided on the brand, but have a few in mind, any suggestions are welcome.

Here is a layout I have been working on tonight for panel layout on the SW facing slope of the pool house roof, shallow slope on roof, I forget the exact angle, but easily walkable, I think about 4 ft rise over 20 ft of slope. Due to the shallow slope and location of house / garage in front of the pool house there is not much view of the panel layout on the roof from ground level.

Again any thoughts are most welcome, do I need more slope on the panels, this is about 2 inches of rise on each 4 ft wide panel.

thanks

Ike
 

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If both the supply and return lines need to go over the roof ridge, you might be better off putting the VRV on the supply line at the peak of the ridge and removing the VRVs on the return lines. Especially if you have a solar valve on the supply line at the pad. This will help maintain a siphon on the return line which will help remove most of the water in the panels and the pipes. On the return line at the pad, make sure there is a check valve back into the plumbing to prevent back filling when solar is off.

But if you can drop the supply line over the edge of the roof at the bottom of the panels, they would drain much better.
 
So the way you have it laid out, the panels are not going to be balanced. I think you want to be sure all the water has to travel the same distance. In your picture, the water in the right bank has a shorter run than the left bank ... so more water is likely to go through the right bank than the left.

If you ran the hot PVC out of the right bank back to the middle and tied them together there and then PVC back to the right, then that should balance the flow (although require a little more PVC).

You will certainly also want to add a drain on the low point that you can open in the winter when you want to drain all the water out of the panels.
 
Ok, one more question, any thoughts on AquaTherm (Elm+) panels vs Techno_Solis, it seems from what i have found they are both priced similarly, Aquatherm may have better optional mounting hardware for the headers, specially designed vacuum breaker, and are repairable by plugging, vs the Techo-Solis which has what seem to be easier to install strap hardware, use standard U clamps for headers, and while not repairable by plugging seem to offer a good warranty replacement program for leaking panels.

Ike
 
They have arrived, for those of you that may have wondered how 4x12 solar panels are packed for shipping here is your answer: Now I just have to get them to the pool, I had them delivered to my work address since we have a loading dock and fork lifts.
 

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Well this project is slowly progressing, I have people coming to help install the panels next week, so it is time to finalize the design. Therefore can I get you to look at this block diagram of the plumbing and see if you think I need to change anything (I am partly working within the confines of existing plumbing so some of the L's and T's shown already exist.

thanks Ike
 

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I'm happy to see you went with just one vacuum relief valve. That's all you need.

I agree with the comment that you should put the VRV at the highest point if you are going over the peak, but it's not totally necessary if the height difference from the top header to the peak is small - a few of feet or less. In fact, one local competitor installs their brass VRV in a tee in the feed line on the wall just above the bypass valve. I don't agree with the practice, but the panels do drain ultimately.

How are you enjoying the system a few year in? Meeting your expectations? Any problems?
 

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Well the panels are up (mostly), the weather was crazy here today, a cool front blew through during the night with some high winds, we had some occasional showers and moderate winds this morning, at noon the wind was blowing from the north and the temperature was up to the 50's. Due to the weather our planned 8 am start was delayed until about 2 pm, by which time the sun was back out things had dried off, wind had mostly died down and the temperature was up into the upper 60's maybe even the low 70's The plumbing run up to the feed point on the headers and from the common point on the hot side return still needs to be ran, and a few things need to be sorted out on the plumbing at the pad (adding in another check valve, etc.) Here is a photo of the progress at about 4 hours into the intstall.
 

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The mounting is using strips of composite decking boards to raise the mounting hardware even with the height of the ridges in the roof, I also had planned to use strips of 3mm PVC sign board as rub strips, but I am not yet sure if they are going to be needed, as it looks like the panels will ride smoothly on the ridges of the metal roof (all mounting screws are in the valleys). The roof panels are McElroy R panels http://www.mcelroymetal.com/content/pro ... duct_id=24 which have their main 1.25 inch high ridges spaced 12 inches apart, which so far seems to provide good support, we will know more when there is water in the panels, is needed I can go back in and insert strips of 1 inch thick composite decking laminated with a 6mm strip of PVC board for the panels to ride on spaced half way between the panel ridges.

Headers are attached with Aquatherm 2 inch clamps http://www.infinigi.com/elm-2-aluminum- ... -5007.html (the spec sheets show the Techno-Solis and AquaTherm 2 inch headers are within about .05 inches of the same diameter, and I liked the idea of these clamps better than the plastic coated U shaped pipe hangers TechnoSolis uses)

Well it is time to get back to supervising, the workers should be here any minute.

Ike
 
Well it is almost done, we were one 90 degree fitting and couple of pipe hold down clamps short, and I still have to finish up the new through wall and drain fittings, it is a good thing I decided to replace the old ones (20+ years old) as I was able to pull the glued on valve off the end of the pipe while trying to break the already cut off pipe free of the caulking in the wall. With luck the weather will hold out and I will get everything going this weekend. Cross your fingers and hope there are no leaks.

Ike
 
I went with stainless U shaped pipe mount brackets from the electrical section at a local hardware store, they are designed to hold electrical conduit, but they had a size that fits snug on standard 2 inch PVC couplers and other fittings.
 
Isaac-1 said:
I went with stainless U shaped pipe mount brackets from the electrical section at a local hardware store, they are designed to hold electrical conduit, but they had a size that fits snug on standard 2 inch PVC couplers and other fittings.
Click to expand...

If I'm understanding you right, that's a mistake. on the roof you do not want snug fitting pipe clamps. Expansion and contraction can cause the fasteners to rip out of the roof. You want the pipe to be able to move horizontally relatively freely while supporting the pipe vertically.
 
I did keep that in mind, these clamps fit snug on the couplers, but allow for slip when fitted along the pipe sections, so are mounted on the couplers for the supply run up to the roof area, and along the surface of the roof where the panels are mounted are fitted along the pipe where there is some free play for slip.

Ike
 
Isaac-1 said:
I did keep that in mind, these clamps fit snug on the couplers, but allow for slip when fitted along the pipe sections, so are mounted on the couplers for the supply run up to the roof area, and along the surface of the roof where the panels are mounted are fitted along the pipe where there is some free play for slip.

Ike
Click to expand...

Sounds good. If you put a clamp at the fittings right at the 90 near the headers, keep in mind that the entire array of panels may expand and contract horizontally, As long as you've considered this dynamic situation, you should be okay. In my neck of the woods, the range of motion can be surprisingly large.
 
One final update until I get a chance to post detailed photos, everything is up and running (at least in manual mode until I get the new temperature sensor for my solar controller wired), still need to put some touch up paint on the fittings, I am getting about 48 gpm of flow when fully diverted through the panels with freshly cleaned filter, with about 5 psi of backpressure measured after the flow meter going to the panels, this seems to be mostly restriction from the 1.5 inch pool return line. Prior to cleaning the filter (first full cleaning of the year)I was getting around 43 gpm of flow.
 

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