Solar HW: Comments?

brn3aFebruary 26, 2008

Hi all,

I am not sure if this is the right place to ask this questions, but...

We live in central Virginia and have 3200 sqft house (well insulated). We already heat with hydronic radiant heat and with propane as the power source. We want to add solar HW to the system to help with winter heating and DHW, especially in light of the tax credits, the skyrocketing cost of propane and other tangibles and intangibles.

Anyway, we have gotten a quote for a system. I am pasting the text below of the system:

The solar system provides active solar hydronic heat collection and storage using American Energy Technology 4 x 10 solar panels with black crystal coating, and a drainback heat storage tank with DHW heat coils. The system uses a drainback design to eliminate potential for overheating, freezing and nighttime losses. The heat storage module is an unpressurized, polyethylene tank with copper coils for the domestic hot water and integrates with the radiant system. The price includes 5 AET panels with flush mounting hardware for direct mounting to the roof and solarsil flexible couplings, the Delta T control, the storage tank, bronze solar pump. and tubing & insulation from the roof to the mechanical room. The panels are planned to be flush mounted to the garage roof. Included is a 1 ½ton heat pump to raise the solar supply temps to make optimal use of solar panels in the heating season.


Now some questions:

1) General thoughts on this system?

2) Are 5 4x10 panels enough? Too much?

3)What about the heat pump? Seems like overkill to me, though our water is from a well and pretty cold.

4) Is the cost reasonable for this system?

5) Is a simpler solution practical?



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200 ft of collector seems way too small and I have never heard of adding a heat pump to boost solar. It does not state the size of tank and the polyethylne may not handle the heat.
No pricing for labor?

You have the right idea about using solar with your system but maybe check around
go to for lots of info

    Bookmark   February 28, 2008 at 8:03PM
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Thanks for the input. I'll check that site out.


    Bookmark   February 29, 2008 at 8:36AM
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Have you considered a tankless water heater? We have just started to investigate them ourselves, but they are no way near the $10K you were quoted above.

We have also learned about the Drain Water Heat Recovery type of device which has no moving parts and can warm fresh water coming into the home that is going into the water heater to ensure what comes out of the water heater is sufficiently hot. I have read where in colder climates this can be an issue with some, not all, tankless water heaters.


PS. I second the Build It Solar site. Gary has done a remarkable job in collecting all sorts of very useful information on energy conservation and renewable energy sources for the home.

    Bookmark   February 29, 2008 at 10:46PM
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i would look into using evacuated tube solar panels and a superstor water tank with two coils, 1 for the radiant and 1 heated by the solar

    Bookmark   March 3, 2008 at 12:23AM
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Hi all,

Thanks for the comments. I did get some clarification from my solar contractor. More details about my current system. I have RFH (powered by a propane Polaris WH). The plan would be to direct the winter solar gain into the RFH *return* line. This line can then be directed back into the RFH system directly (without heat exchangers). Problem is that in the winter, the heat gain from the solar panels may be less than the RFH return temp. Hence the heat pump. It would be a water-->water heat pump and heat the solar water (from lets say 75F) up to the required temperature for the RFH. I'm still not convinced it is necessary and adds a layer of complexity, but it certainly sounds like it would work.

In the non heating season, solar gain would be directed to to the cold water supply of the Polaris to provide for DHW.

Im waiting on a diagram of the whole thing. I'll check back when I get one.


    Bookmark   March 4, 2008 at 1:18PM
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