solar collector design -Big, 24′ X 8′ Solar Collector Using PEX Tubing – Step by Step How to Build

November 26, 2012 – 3:28 pm

** This video shows step by step how I built my 24 ‘X 8′ solar collector, using PEX instead of copper. Using PEX, is much easier to construct and less expensive too! Anyone can build this project! We are using the collector for winter heating and space heating of the sanitary water too! Video Rating: 5 / 5

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  1. 25 Responses to “solar collector design -Big, 24′ X 8′ Solar Collector Using PEX Tubing – Step by Step How to Build”

  2. Hi VederchiHarry,

    Typical collectors have an efficiency of about 50%. I agree, the pex collector is running less, but I think the similar CPVC design has remedied that, Please see my later CPVC collector video. Gary over at Build It Solar did a side by side comparision with Copper / Aluminum and they were almost identical! I think this PEX version could be made more efficient with additional, parallel runs as well, mirrioring the CPVC design.

    By G. Scott Davis on Nov 26, 2012

  3. area = 192 sq feet.
    solar power = 100 W/sq feet/hour (best part of the day)
    time = 4 hours
    maximum solar energy = 192sq feet x 100W/sqfeet/h x 4h = 76′800 W = 76.8 kW

    Now, he says that it can warm up 200 gallons from 85 to 125°F in 4 hours. This requires an energy of 19.54 kW

    Therefore the effiency is : 19.54/76.8 = around 25%

    Best solar pannels have an effiency of 80% (and even up to 90%).

    With 75%, we have : 75% x 192 sq feet x 100W/h/sq feet = around 14kW/h

    By VederchiHarry on Nov 26, 2012

  4. Welcome, thanks for joining the group! It is much easier to discuss solar there where posts aren’t character constrained!

    By G. Scott Davis on Nov 26, 2012

  5. Hi Brandon, thanks for your thoughts and interest!

    I’m only losing 2F – 3F on the run back to the house. For example, if the fluid leaves the collector at 135F, it reaches the storage tank (more than 100 feet away) at about 132F.

    By G. Scott Davis on Nov 26, 2012

  6. ha, I realized I’m really really interested in this… so I just joined your group!

    By BrandonFound on Nov 26, 2012

  7. continued…… I used to install utilities and know most everything about conventional water heating systems (gas and electric, solar is my new frontier). Do a simple test, drill a small hole in the PEX just above where it runs underground. Drill another hole just above where the PEX leaves the soil or enters the house. Insert a small electric thermometer like you’d use to take a fever in both holes and do the math. If there’s concerning heat loss I believe I have a solution.

    By BrandonFound on Nov 26, 2012

  8. I’m familiar with PEX and the material you used to insulate the PEX during the sub-terrain run to storage. Your going to be losing a lot more heat than you think if your app is as it is shown in this video. That insulation, while cheap, convenient and temptingly tailor made for the situation is only meant to keep scolding hot water warm on a journey no longer than 100 feet through structure that itself acts as a thermal insulator, IT IS DESIGNED TO LOSE HEAT ENERGY.

    By BrandonFound on Nov 26, 2012

  9. I’m not being sarcastic, I’m genuinely interested in what you have to say so do you care to enlighten us on an application that will yield closer to the 100% 14kW/h potential?

    By BrandonFound on Nov 26, 2012

  10. Yes, please see my thermal storage video for how I’m handling heat storage and heat transfer.

    By G. Scott Davis on Nov 26, 2012

  11. so do you have any suggestions on heat transfer and/or storage. I have below freezing temps. so I have to use a closed loop system with some sort of exchanger and potable hot water storage tank

    By Kubotajoesfarm on Nov 26, 2012

  12. I’m sorry but your model is not very efficient. You’re getting only 4.3 kW/h (efficiency = 25%) where You could get up to 14 kW/h with the same area.

    By VederchiHarry on Nov 26, 2012

  13. Yes, i agreee that closer spacing would work better. I’ve been thiking about putting a secon run in parallel between the first using two Ts, which would effectively give a 3″ spacing and also reduce flow resistance. Please see my CPVC collector video for the good performance I’m getting with more closely spaced tubes.

    By G. Scott Davis on Nov 26, 2012

  14. Hi, the pex is procted from UV in two ways. First, the SunTuf glazing is UV protected, so that keeps the harmful rays from hitting the pex. Second, the pex itself is painted black, which is a second layer of protection from UV rays.

    By G. Scott Davis on Nov 26, 2012

  15. you could have put the pipes much closer together and got loads more heat gain.

    By a10fjet on Nov 26, 2012

  16. lol wikipedia says pex deteriorates extremely fast in UV light. dunno if its true but if it is youre boned

    By a10fjet on Nov 26, 2012

  17. Hi Scott, I’d thought of doing it pretty much this way actually – just wanted your input as you’d actually made it.
    I was thinking of using irrigation tubing as it’s really cheap, and it made of HDPE, which has almost twice the heat conductivity of PVC – just not completely convinced of it’s pressure when hot, as it’s not designed for this application.
    Thanks for your reply.

    By Drafty01 on Nov 26, 2012

  18. Hi, no under floor radiant heat is easy! It’s is really just building a pex collector in reverse. Simply run the pex under your floor, put flashing around it to help spread out the heat and then stuff batt insulation between the joists.

    By G. Scott Davis on Nov 26, 2012

  19. Hi Scott, great presentation. There are not many this good on Youtube, with all the facts & figures as well. I live in Auckland, NZ, and like you, would like to make a dent in the domestic hot water bill, as the price of power just keeps going up. Do you have a video for the underfloor heating system you put in? I was considering doing this, but seemed an expensive project to do.

    By Drafty01 on Nov 26, 2012

  20. Hi, please take a look at my solar thermal storage vide. I think that will fill in the blanks.

    By G. Scott Davis on Nov 27, 2012

  21. Hi Scott
    Great video and helping me as great deal..My question is can you show me your entire system and how it works from start to finish.. Maybe a diagram? How do you keep your hot water and in what? Thanks for doing these vids its a big help to me as I am getting started on saving money on utilities..

    By LOLITSCOURTNEY on Nov 27, 2012

  22. I think mirrors could give you a substantial increase in energy gain for a fraction of the cost of constructing another unit. With snow in mind, plywood covered with aluminum foil or flashing removes breakage concerns. The drainback design would allow the addition of a radiant heating line for the reflectors, or just spray the snow with warm water.

    By kpeavey2 on Nov 27, 2012

  23. Hi, we are saving more than 30% each month during the coldest months and much more during the “shoulder” months (Oct, Nov, Mar and Apr) on space heating. Of course, we are saving on domestic hot water heating year round on top of that.

    Regarding cost, very roughly:

    12 pieces Sun Tuf glazing ($240)

    6 polyiso insulation ($100)

    6 5/8″ plywood ($150)

    6 3/8″ plywood ($100)

    8 2 X 6s ($35)

    11 2 X 2s ($22)

    flashing ($100)

    300′ of Pex ($150)

    Mis ($100)

    Total was $997.

    By G. Scott Davis on Nov 27, 2012

  24. That’s awesome. Hoe much money do you think it saves you and what was your cost for the build?

    By FloridaSalon on Nov 27, 2012

  25. I used SunTuf, available at Home Depot (Lowes has Tuftex, which is essentially the same). It works well. A double glazing would insulate more, but reduced light transmitance, so the single glazing is fine here in Maryland, where typical winter temperatures are in the 30s.

    By G. Scott Davis on Nov 27, 2012

  26. how well does this plexi glass work in the winter, is there a lot of heat loss ?

    By bosdad7 on Nov 27, 2012

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