Solar Panel Layout: 8 panels- 2 rows of 4

[jblively]

I'm finally getting around to mounting my solar panels. They are sungrabbers, low cost.

I have a 21x41 oval above ground pool. It's big, so I have 8, 2x20 panels. My roof is 45 degrees, facing directly south. It's pretty much a very good setup for them. BUT..

I don't know how to route the water! The issue is because I am doing 8 panels, I can't stack them all in a row, I have to have two rows of 4. But the headers go north/south, not east west. I've attached what I was thinking, but seems pretty complex. but if the goal is to have the water spend as much time in the panels as possible, I think it makes sense.

I'm new to this, and I apprecaite all your guys help.

-Topic Edited to make it useful for people doing similar setups.

Joe

 

[solarboy]

Re: Solar Panel Layout

The layout you have drawn seem the most inefficient way to do it. The water will end up too hot by the end of the route which means a greater difference in temperature between the water and the surroundings, which will cause a greater loss of heat though the pipework. Ideally you'd have a feed and return from each panel. Make sure all the feeds come from a single high point so as to ensure the panels all have the same total distance of pipework (even if you don't drill out the header you should do this).
Try looking around this site ; http://www.h2otsun.com/

 

[jblively]

Re: Solar Panel Layout

The layout you have drawn seem the most inefficient way to do it. The water will end up too hot by the end of the route which means a greater difference in temperature between the water and the surroundings, which will cause a greater loss of heat though the pipework. Ideally you'd have a feed and return from each panel. Make sure all the feeds come from a single high point so as to ensure the panels all have the same total distance of pipework (even if you don't drill out the header you should do this).
Try looking around this site ; http://www.h2otsun.com/

Hmm, I see how they have it mounted, but I can't turn them that way on my roof, as they are 20 feet long and my roof is only 15 feet. That's my main issue...wrong orientation. But I have to make it work on a 2 column but 4 row setup.

 

[jblively]

Re: Solar Panel Layout

is this any better?

 

[solarboy]

Re: Solar Panel Layout

It's better but you've still got the water going through multiple panels and getting too warm. I get what you're saying about the panels being too "long" for your roof. They would still work if you plumbed them together in the standard way but on it's side but you'd have to manually drain them down and if you live in a frosty area that could be problematic. Another option would be to build a small rack to extend your existing roof, but it probably wouldn't be pretty (probably). Just out of interest, how flat is the roof? Some of the experts may have some ideas when they get on line also.

 

[solarboy]

Re: Solar Panel Layout

I have had a thought ! The design below shows a set-up that should work. I'm not entirely sure weather you could get it to automatically drain, but you could fit a manual drain at the bottoms of the cold feeds to each bank of panels. The slight angle should ensure drainage.

 

[solarboy]

Re: Solar Panel Layout

This design is probably better as the hot and cold lines are similar length.

 

[solarboy]

Re: Solar Panel Layout

Or even this...

 

[JasonLion]

Re: Solar Panel Layout

solarboy's next to last diagram is very nearly what I would recommend. The only change I would make is to move the blue water feed line to the bottom of the panels instead of the top. You want water to go up and up and up until it gets to the top and then go down and down and down. You never want water to go up and then down and then up again or you get an area that won't drain.

Something like:[attachment=0:1af9rdtl]SOLAR5TFP.jpg[/attachment:1af9rdtl]

 

[jblively]

Re: Solar Panel Layout

This design is probably better as the hot and cold lines are similar length.

This is doable. To answer your questions, it's 45 degrees (NOT fun to work on) I live in Oregon,and we get frosty winters, but I was going to add a manual drain at the bottom to account for that issue.

I guess I have a lot to learn...it just seemed that the longer the water was in the panels, the hotter the water would get, and the more it would heat my 25,000 gallon pool!

Thank you so much for the help, SB and Jason.

 

[NWMNMom]

Re: Solar Panel Layout

You will have a lot less PVC if you flip over all of the panels on the right side so that you are plumbing both sets from the center. By flip over I mean the panels have a sticker on the front of the feed header that faces up/out - flip those right panels upside down so that they face IN to the roof/surface. It will not hurt them, the do not operate any differently and you can plumb all the INs and OUTs from the center - using less pvc

 

[jblively]

Re: Solar Panel Layout

You will have a lot less PVC if you flip over all of the panels on the right side so that you are plumbing both sets from the center. By flip over I mean the panels have a sticker on the front of the feed header that faces up/out - flip those right panels upside down so that they face IN to the roof/surface. It will not hurt them, the do not operate any differently and you can plumb all the INs and OUTs from the center - using less pvc

That's a great idea!

Also, question on that subject: Is it ok to use ABS rather than PVC? It doesn't get too hot out here. 100 degrees is rare. I'd just rather not look at the white PVC on the roof.

Joe

 

[jerryls]

Re: Solar Panel Layout

Personally, i would use your original idea of all in series. If you live in Oregon the water will not get much above 90-100 degrees, if that. You can easily insulate the outside of the return pipe. The problem with any parallel approach is that water will take the least path of resistance. The flow will be different in each panel. Of course, the serial approach will have a little more backpressure to push it through however.

 

[JasonLion]

Re: Solar Panel Layout

Parallel plumbing is something on the order of four to six times as efficient in this configuration.

I would use PVC. You can paint the pipes to match your roof. Use a paint like Krylon Fusion that is designed to work with PVC.

 

[jblively]

Re: Solar Panel Layout

Personally, i would use your original idea of all in series. If you live in Oregon the water will not get much above 90-100 degrees, if that. You can easily insulate the outside of the return pipe. The problem with any parallel approach is that water will take the least path of resistance. The flow will be different in each panel. Of course, the serial approach will have a little more backpressure to push it through however.

Backpressure isn't an issue. Big 2hp pump. So, I could do series, no problem.

Jason: When you talk about more efficient, what do you mean. Less stress on pump, better heating ability, theoretically correct? What if I run it in parallel and it doesn't get hot enough? 25,000 gallons!

Also, what's the benefit of using PVC over ABS? i'm ok with painting and stuff, but would like to know why ABS isn't ok for an oregon install.

Thanks.

Joe

 

[jblively]

Re: Solar Panel Layout

So looking at these two options, they both look about the same, NWMNMom Suggestion saves 1 joint ,and about 10 feet of piping it looks like, but both of these look to me easier than my first 2 'drafts'

Jason, I changed the routing of the Hot water coming out to cut back on the pipe needed, and returned on the top, rather than wrapping around the bottom as you suggested. Any issues with that?

Thanks,

Joe

 

[JasonLion]

Re: Solar Panel Layout

You will get way more heat out with everything plumbed in parallel. You also need the distance traveled and vertical height traveled to be the same regardless of which panel the water goes through.

Neither of the new drawings have uniform path lengths, ie water going through some panels travels a shorter distance than going through others.

You can move the return pipe to the top, instead of the bottom, but water from all panels still needs to go all the way to the left. Or in the lower drawing you could return water from the right hand bank along the top to the middle and join up there and return from there.

 

[solarboy]

Re: Solar Panel Layout

Personally, i would use your original idea of all in series. If you live in Oregon the water will not get much above 90-100 degrees, if that. You can easily insulate the outside of the return pipe. The problem with any parallel approach is that water will take the least path of resistance. The flow will be different in each panel. Of course, the serial approach will have a little more backpressure to push it through however.

It's about loss of head which means using more electricity to do the same amount of water turnover. Parallel is always better. Also the speed of water going through the panels won't affect drastically how much heat is absorbed from the sun, but rather, if the water gets too hot the temp DIFFERENTIAL to ambient becomes greater, and more heat is lost.

 

[chem geek]

Re: Solar Panel Layout

Several years ago, we moved one panel in our existing 12 panel system and initially the solar company plumbed it as a separate branch so the path length was longer for that solo panel than for any of the others. I had noticed that it didn't seem to be heating the way that it should and it didn't "sound" the same as other panels when I put my ear to the header tube. I also noticed that it wasn't cooling off the room underneath it as much as I had expected and that the panel was hotter than it should have been (and hotter than the other panels).

So I had them replumb to make the path lengths equal which meant that the hot water return started from the furthest panel. While this increased the path length for everyone (i.e. all panels), it made them all equal. All of the problems then went away -- the panel remained cool like the other panels, the system heated a little faster than it used to, the sound of water flow was similar to other panels and the room under the panel was noticeably cooler. So my personal experience is that, at least for long pipe runs, having the same path length for all panels makes a big difference. All panels are also in parallel.

 

[jblively]

Re: Solar Panel Layout

So I had them replumb to make the path lengths equal which meant that the hot water return started from the furthest panel. While this increased the path length for everyone (i.e. all panels), it made them all equal. All of the problems then went away -- the panel remained cool like the other panels, the system heated a little faster than it used to, the sound of water flow was similar to other panels and the room under the panel was noticeably cooler. So my personal experience is that, at least for long pipe runs, having the same path length for all panels makes a big difference. All panels are also in parallel.

Thank you! I was going to ask why does equal lengths matter? but this answers it perfectly.

Ok Guys, I think this might be the final: