What's the cheapest way I can mount 5 4x10 solar panels to my roof?

[Dirk]

Thanks Mark. That is quite a sheet!! It's gonna take me a while to fill in all the input...

 

[Poolzzz]

...I could have gotten more out of my panels. 14% (or whatever the loss is in my case) is not insignificant.

It varies with location, time of year and obviously roof pitch.

That example was for your "best case" in mid-summer. It's worth doing the same calculation for mid-september also.

And, so not to hijack the thread any more than it has already, worth looking at the OPs location of Portland for comparison.

Using Fresno for Dirks location we get:

1) Mid-summer = 14% loss
2) Mid-september (35 deg off zenith) = 35% loss

And for the OP's Portland location:

1) Mid-summer (22 deg off zenith) = 20% loss
2) Mid-september (45 deg off zenith) = 50% loss

This assume a roof pitch of 15 deg as per Mark's example which is a very flat roof to us Northerners. Around here roof pitch is at least 26 degrees (presumably due to snow loads). If Portland is similar then the numbers become 33% and 68% loss respectively.

 

[Dirk]

Thanks Poolzzz! And unfortunately for me, it's September I most need the efficiency (and May). My pool is plenty warm enough in the summer. I have to run the pump for SWG anyway, and I have PV solar, so electricity costs are mostly a non-issue. But I'm not getting the extra weeks on each end of the season I was hoping for...

My location gets cooler at night than Fresno, so I have to deal with that, too, since I refuse to use a cover.

To bring this around back to the OP's situation: my solar is getting me what I was after, a more comfortable swim during swim season. I wasn't willing (am not willing) to do everything I could to optimize it (number of panels and direction and pool cover), so I don't get all the solar goodness I could.

With Poolzzz's estimates, I stand corrected (or rather the guys that sold me my panels do), that placement is something to work on, especially in your area.

 

[Slippery]

Solar noon today was 1:10 pm local time in Portland, OR.

For radiation heat loss you're trying to shield from deep space actually. Use a radiation barrier.

What's your source for solar noon calcualtions?

I googled "radiation barrier solar pool panels" and nothing came up.

 

[Slippery]

Also, I have a spreadsheet in my signature that will estimate all the heat gain and loss of a swimming pool with solar panels at a particular location so you can see the effects of different panel placing. It will also allow you to specify simple shadow masks for both the sun and the sky.

Can you link me directly? I couldn't find it.

EDIT: FOUND IT

EDIT 2: I can't upload this to google sheets. Is there another way I can use it with out buying Excel?

 

[Slippery]

It varies with location, time of year and obviously roof pitch.
OP's Portland location:

1) Mid-summer (22 deg off zenith) = 20% loss
2) Mid-september (45 deg off zenith) = 50% loss

This assume a roof pitch of 15 deg as per Mark's example which is a very flat roof to us Northerners. Around here roof pitch is at least 26 degrees (presumably due to snow loads). If Portland is similar then the numbers become 33% and 68% loss respectively.

Thanks so much. OK so how do I transfer these angles to the real world? What tools do I need when I build a simple 2x4" frame for the panels to make sure I am pointing them in the right direction?
Is it possible to do with out purchasing expensive tools?
I will make sure they are out of shadow for peak solar noon (and a few hours on either side of solar noon. Is 3 hours later hotter than 3 hours earlier since the air will be hotter?).
How far off the ground the they need to be and how does height affect their efficiency?
And as I understand the radiation discussion. It would be useful if I could seal them up. Maybe some simple Tyvek house wrap on the bottom and sides (I have extra sitting around). But I assume some kind of clear cover on top would likely block some of the suns heat. Am I correct?

 

[mas985]

I will make sure they are out of shadow for peak solar noon (and a few hours on either side of solar noon. Is 3 hours later hotter than 3 hours earlier since the air will be hotter?).

Afternoon is usually better.

How far off the ground the they need to be and how does height affect their efficiency?

Just enough to get air to flow freely underneath.

And as I understand the radiation discussion. It would be useful if I could seal them up. Maybe some simple Tyvek house wrap on the bottom and sides (I have extra sitting around). But I assume some kind of clear cover on top would likely block some of the suns heat. Am I correct?

No, you don't want to do that. That can actually reduce efficiency. What I was talking about is having objects (i.e. buildings, trees, fences, bushes, etc) that block the sky from the panels but not the sun. This is about placement of the panels rather than adding something.

 

[Dirk]

Compass for pointing. You might have one in your phone (though those are not great). Big Five.

You can establish the horizontal plane angle using a tape measure and some math. A bit easier would be a level and a speed square. Nothing more complicated necessary. Available at any hardware store for 15 bucks or less. If you know how to use a speed square, it'll pay for itself during your build. Find a YouTube on that, you'll be framing like a pro!