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  1. #1
    Join Date
    Jun 2007
    Location
    Near Philadelphia
    Posts
    2

    Default Solar hot water, and...

    Am in the process of getting quotes for solar hot water on my house. Any opinions on:
    a) whether the solar heated water should seed an existing hot water heater or whether I should (as one contractor suggests) replace the water heater with a tankless heater (i.e the only water stored is the solar heated water)
    b) pros and cons of having the roof where the collector is located re-finished before installation - one contractor seems to think its no big deal to remove the collector / tubes while a roofer works, the other thinks we should have the roof done first...
    Thanks...

  2. #2
    Join Date
    Jun 2007
    Location
    Coventry, RI
    Posts
    340

    Default Re: Solar hot water, and...

    I don’t have any experience in this area but what is it that you want the solar hot water for? If it is just for domestic hot water you may just want to skip the solar part and get a tankless water heater. They are very efficient and come on only when you want hot water. I would think that this could be the better way to go since most people use hot water early in the morning and in the evening / at night. Since the water would not be that warm in the morning or in the winter at night you probably would be using a water heater quite a bit. If you really want to go with the solar you should definitely have a highly insulated storage tank. The tankless water heaters are also fairly expensive but last a lot longer than a regular water heater so it would add about $1,200 plus installation to the cost of your solar system.

    As far as the roof I would say it all depends on how much life is left in it. If it will need to be replaced in a few years do it now but if its 15 years I would wait. Good Luck in your project.

  3. #3
    Join Date
    Dec 2007
    Posts
    2

    Default Re: Solar hot water, and...

    I am happy to see that you have not been swayed by the Solar PV pitch. In the interest of fairness I have been selling Solar Hot Water Heaters since 1976. IMHO there wasn't much about the Carter administration that brings fond memories, BUT, he started the ball rolling on solar rebates. Unfortunately the oil crisis subsided; rebates went away and took the business with it. Well as I am sure you know the Federal $$$ is back at up to $2000.00 and this time around several states are kicking in. In Vermont for instance they are giving up to $1800.00 back. This kind of rebate makes these systems sing. The payback can be as low as three years but typically will be in the 5 to 7 year range. To clarify my PV position (PV = Photo electric) When the development catches up to the hype this product will be a winner. Right now an honest answer on the question of payback on PV systems for residential is somewhere in the 20 to 25 year range. My point is we have a proven method with solar thermal, research is going on now and as I said within 5 years or so PV will be attractive. I love the theory, however we have limited resources, I believe the object of the grants is to get these systems up and running and because of the savings and short return on investment on Solar Thermal, we can get those funds spun over and back out assisting more people to reduce fossil fuel usage. Four times or more than granting money on PV systems.

    OK now what was your question!!! Just kidding
    With solar hot water storage is the name of the game. I would keep your existing tank and depending on the usage in your household put in anywhere from 50 to a 120 gallon storage tank with a heat exchanger. I am not sure of your location so you need to make sure you are on top of the freezing issues. Having said my story on storage, the slickest installations I have been involved in use an 80 or 120 gallon solar storage tank and on the outlet side of the tank go into an instantaneous gas water heater. The Feds give out $300.00 for buying the water heater plus up to $2000.00 and whatever your state does. I am trying to compile a list of each states offering.
    If the roof needs repair get it fixed, if it doesnít don't. Thatís what I would use for a filter to make my decision with.
    I hope I haven't confused you more. But you just can not go wrong with solar hot water


    Quote Originally Posted by andrewa View Post
    Am in the process of getting quotes for solar hot water on my house. Any opinions on:
    a) whether the solar heated water should seed an existing hot water heater or whether I should (as one contractor suggests) replace the water heater with a tankless heater (i.e the only water stored is the solar heated water)
    b) pros and cons of having the roof where the collector is located re-finished before installation - one contractor seems to think its no big deal to remove the collector / tubes while a roofer works, the other thinks we should have the roof done first...
    Thanks...

  4. #4
    Join Date
    Dec 2007
    Posts
    2

    Default Re: Solar hot water, and...

    I was quickly looking and saw several posts where it was said if you are just doing domestic let it go. For the reasons I spelled out in my earlier post you are looking at 3 to 5 and MAX 7 year payback. I personally have never put in a system with a 7 year payback but have put in plenty with a 3 year. Heck if you borrow the $$ to put a system in there will be months from the get go that your savings in utility costs will be less than the cost to carry the loan and then in 3 , 5 or 7 years after it is paid off it is all gravey.

    I did want to make one other point clear.
    A correctly sized system will supply 65 to 70 % of your water heating needs. If one were to size it for a 100% then you would have a system that could not be paid back!!
    Again I hope that I have helped and not hindered you on your quest
    Steve

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