Solar panel configuration dilemma

[mas985]

WOW, I'd say your model is pretty well tuned Mark

Thanks but it really helps to have accurate inputs.

In the table below, I finally figured out how to make tables, there are 5 runs. The first is the baseline without solar. Then the next two are solar at high & low speed with short 90s and then the second two are with the long 90s. Also I made a minor change to the model to add a short section of pipe between the pump and filter that I forgot before. Interesting thing is that there seems to be enough pressure at low speed at the input and output of the panels should you want to have a VRV at that location. I used 10.5' for both since I did not know the actual height of the panel output section. However, it might still be a good idea to put the VRV a little lower on the supply pipe; especially if you want to have a manual vent valve first.

[tr:lgrzc6n5][td:lgrzc6n5] Summary [/td:lgrzc6n5][td:lgrzc6n5] [center:lgrzc6n5]No Solar[/center:lgrzc6n5] [/td:lgrzc6n5][td:lgrzc6n5] [center:lgrzc6n5]Solar Short 90[/center:lgrzc6n5] [/td:lgrzc6n5][td:lgrzc6n5] [center:lgrzc6n5]Solar Short 90[/center:lgrzc6n5] [/td:lgrzc6n5][td:lgrzc6n5] [center:lgrzc6n5]Solar Long 90[/center:lgrzc6n5] [/td:lgrzc6n5][td:lgrzc6n5] [center:lgrzc6n5]Solar Long 90[/center:lgrzc6n5] [/td:lgrzc6n5][/tr:lgrzc6n5][tr:lgrzc6n5][td:lgrzc6n5] Pump Speed (rpm) [/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]3450[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]3450[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]1725[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]3450[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]1725[/center:lgrzc6n5][/td:lgrzc6n5][/tr:lgrzc6n5][tr:lgrzc6n5][td:lgrzc6n5] Water Flow (gpm) [/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]45.0[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]40.8[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]20.2[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]41.1[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]20.4[/center:lgrzc6n5][/td:lgrzc6n5][/tr:lgrzc6n5][tr:lgrzc6n5][td:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5][/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5][/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5][/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5][/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5][/center:lgrzc6n5][/td:lgrzc6n5][/tr:lgrzc6n5][tr:lgrzc6n5][td:lgrzc6n5] Suction Head Loss (ft) [/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]2.2[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]1.3[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]-1.9[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]1.4[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]-1.9[/center:lgrzc6n5][/td:lgrzc6n5][/tr:lgrzc6n5][tr:lgrzc6n5][td:lgrzc6n5] Pad Head Loss (ft) [/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]18.0[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]12.6[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]3.1[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]12.8[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]3.2[/center:lgrzc6n5][/td:lgrzc6n5][/tr:lgrzc6n5][tr:lgrzc6n5][td:lgrzc6n5] Solar Head Loss (ft) [/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]0.0[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]13.2[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]3.4[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]12.4[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]3.2[/center:lgrzc6n5][/td:lgrzc6n5][/tr:lgrzc6n5][tr:lgrzc6n5][td:lgrzc6n5] Return Head Loss (ft) [/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]5.7[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]5.3[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]3.6[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]5.3[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]3.6[/center:lgrzc6n5][/td:lgrzc6n5][/tr:lgrzc6n5][tr:lgrzc6n5][td:lgrzc6n5] Jet Head Loss (ft) [/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]21.7[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]17.8[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]4.4[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]18.1[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]4.4[/center:lgrzc6n5][/td:lgrzc6n5][/tr:lgrzc6n5][tr:lgrzc6n5][td:lgrzc6n5] Total Head Loss (ft) [/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]47.6[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]50.2[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]12.6[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]50.0[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]12.6[/center:lgrzc6n5][/td:lgrzc6n5][/tr:lgrzc6n5][tr:lgrzc6n5][td:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5][/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5][/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5][/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5][/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5][/center:lgrzc6n5][/td:lgrzc6n5][/tr:lgrzc6n5][tr:lgrzc6n5][td:lgrzc6n5] Input Power (Watts) [/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]1150[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]1119[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]270[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]1121[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]270[/center:lgrzc6n5][/td:lgrzc6n5][/tr:lgrzc6n5][tr:lgrzc6n5][td:lgrzc6n5] Gallons/Whr [/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]2.35[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]2.19[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]4.49[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]2.20[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]4.52[/center:lgrzc6n5][/td:lgrzc6n5][/tr:lgrzc6n5][tr:lgrzc6n5][td:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5][/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5][/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5][/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5][/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5][/center:lgrzc6n5][/td:lgrzc6n5][/tr:lgrzc6n5][tr:lgrzc6n5][td:lgrzc6n5] Suction (in hg.) [/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]1.96[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]1.16[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]-1.67[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]1.22[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]-1.65[/center:lgrzc6n5][/td:lgrzc6n5][/tr:lgrzc6n5][tr:lgrzc6n5][td:lgrzc6n5] Filter Pressure (psi) [/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]16.57[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]18.41[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]4.62[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]18.27[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]4.59[/center:lgrzc6n5][/td:lgrzc6n5][/tr:lgrzc6n5][tr:lgrzc6n5][td:lgrzc6n5] Panel Input Pressure (psi) [/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]NA[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]13.68[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]1.00[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]13.69[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]1.00[/center:lgrzc6n5][/td:lgrzc6n5][/tr:lgrzc6n5][tr:lgrzc6n5][td:lgrzc6n5] Panel Output Pressure (psi) [/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]NA[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]12.34[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]0.67[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]12.33[/center:lgrzc6n5][/td:lgrzc6n5][td:lgrzc6n5][center:lgrzc6n5]0.67[/center:lgrzc6n5][/td:lgrzc6n5][/tr:lgrzc6n5][/table:lgrzc6n5]

Power levels are a rough approximation.

 

[linen]

In the table below, I finally figured out how to make tables, there are 5 runs. The first is the baseline without solar. Then the next two are solar at high & low speed with short 90s and then the second two are with the long 90s.

Thanks for the table! Was that hard to do? It looks like a formatting nightmare.

Those calcs really drive home your point about the short verses long 90s. I think I have struggled with it since I had no empirical evidence and my "common sense" seemed to think it mattered. It is nice to see it modeled.

Interesting thing is that there seems to be enough pressure at low speed at the input and output of the panels should you want to have a VRV at that location.

I think I will put just the connection for the VRV above my supply valve ~ 5 feet above pump. What size thread is typical for VRVs?

I used 10.5' for both since I did not know the actual height of the panel output section.

I think the input to the panels will be about 8' above the pump outlet and the output of the panels will be 6.7 feet above that (6/12 roof, 14.9' total distance from lower panel right to upper panel left, which includes a 5 inch horizontal slope for draining, and five inches at lower right and upper left for nipple attachment and 90s).

 

[linen]

Now a question for anyone about attachment to the roof.

Last year I used the fabric webbing straps that sungrabber supplied to attach/hold down the panels to the roof. I am not very happy with this method as the edges where the straps and strap anchor to roof were caused damage to the outer most tubes. Not so much that they leaked but I don't think much/any flow is getting through.

Ideally I would like to just anchor the manifold, but I am assuming expansion and contraction makes this a bad idea in addition to the "sail" of the panels in wind.

Anyone know of a better way?

Also, what is a good way to attach the supply and return pipes to the roof? Strapping? U clamps? Other ways?

 

[carlscan26]

You can use clamps for the header and two sets of straps across the panels to keep them down. You don't want both sides clamped down because of expansion and contraction.

 

[mas985]

What size thread is typical for VRVs?

1/2" thread.

Thanks for the table! Was that hard to do? It looks like a formatting nightmare.

Not really, I just wrote an Excel VBA script to automatically reformat selected spreadsheet cells into phpBB code that can be transfer into the post via the clipboard. The code is shown below:

Sub MakeBBTable()

    Dim doClip As DataObject
    Set doClip = New DataObject
    
    Dim rSrc As Range
    Set rSrc = Selection
   
    Dim sText As String
    sText = "[table=2]" & vbNewLine
   
    'Loop through the rows, then the cells
    
    Dim firstRow As Boolean
    firstRow = True
    
    Dim rCell As Range, rRow As Range
    For Each rRow In rSrc.Rows
        ' Use first column in spreadsheet as row labels for table
        sText = sText & "[tr]" & "[td][b]" & ActiveSheet.Cells(rRow.Row, 1) & "[/b][/td]"
        For Each rCell In rRow.Cells
            If firstRow Then ' Column labels
                sText = sText & "[td][b][center]" & rCell.Text & "[/center][/b][/td]"
            Else ' Data cells
                sText = sText & "[td][center]" & rCell.Text & "[/center][/td]"
            End If
        Next rCell
        sText = sText & "[/tr]"
        firstRow = False
    Next rRow
   
    sText = sText & "[/table]"
   
    'Put sText into the DataObject
    doClip.SetText sText
    'Put the data in the DataObject into the Clipboard
    doClip.PutInClipboard
   
    Set doClip = Nothing
   
End Sub

 

[Bama Rambler]

Thanks for posting that Mark. That makes it a lot eaiser than hand coding.

 

[mcoonan]

linen,
These are what I used on the roof and on the wall.
http://menards.com/main/plumbing/rough- ... c-9422.htm
Mike

 

[solarboy]

Heliocol use what they call "crocodile clamps" to hold down the manifolds. I've fitted them and they work very well and leave play for expansion. You could probably fabricate something similar in aluminium or something.
http://www.nextag.fr/serv/fr/buyer/prod ... 1719190100

 

[linen]

I thought I would post an update...I did plumb all six panels in parallel.

With my fingers crossed, I diverted my flow to the panels and I had a waterfall coming off the roof
Turns out one of my older panels (used last year) has damage on one side in a line perpendicular to the long axis of the panel. It was interesting that only every other small tube was damaged. My best guess is that when my oldest son and I were getting them up on the roof, he let go for a second and they rubbed against the edge of the shingles that were sticking out from the edge of the roof. I have temporarily "fixed" it by using an approach I read on here where I ground down #6 countersink screws and put those into the manifolds at each end of the leaking small tubes. Very small leaks still exist, but not bad enough we can't run for now and not bad enough that the water is able to drip off the roof before it evaporates on a hot day. 14 of the small tubes were leaking out of ~ 100 on this panel panel (not sure of exact total per panel). I am currently waiting the hear back from the vendor if I can get any warranty coverage on this. I dislike the fact that sungrabber insists that these have to be taken down in the winter to not void the warranty. Seems like there is as much risk moving them as there is in not getting them blown out. I did notice during the process that the manifolds on these only have about 6 openings to the main/feeder tube, so there must sub-plenums that exist in the header...I can imagine these might be part of the reason why sungrabber doesn't recommend blowing them out, since it would be hard to get the water out of these hidden crevasses.

So, the big question...can I run on low? YES ...with some caveats :| :

1. It seems the panels need to be primed on high or I end up getting no/low flow at pool.
2. When I have full sun on the panels at mid-afternoon, my temperature delta has been as much as 11F when running on low (and about 5F on high). Seems too high for efficient heating?
3. When I am running on low through the solar...it seems that I am right on the edge of too low flow for my intex swg. I have found when it starts beeping and stops producing, then I have to backwash the sand filter too get enough flow to allow the swg to run. This means I am backwashing more frequently then the tfp recommendation of 25% rise over "clean" pressure.

These three issues have meant that I have been generally running on high. As I get more run time, I will update.

 

[linen]

linen,
These are what I used on the roof and on the wall.
http://menards.com/main/plumbing/rough- ... c-9422.htm
Mike

mcoonan, thanks for the post!

I ended up using ~10 of these for anchoring my pvc pipes, and I really like them. I used the middle anchor hole and used some 1/2" hex, 1.5" long stainless lag screws.

 

[linen]

Well after 3 days of cool weather (highs in upper 60s and low 70s) and no sun, the pool was back down to 72. We have some sun today, so hopefully will be able to bump up temp again...we were at pool temp of ~85, before the cool cloudy snap. Running on high and getting about 4.5F bump through panels at our peak heating hour (2 pm). Also tested running it at low I am getting about 9.5F bump. I think the difference between 5/11F before is the steady breeze we have today. Here is a pic of my oldest keeping warm by the return and the choppy water due to the breeze: