Solar watert heater

NomoreNomore Registered Users Posts: 18 ✭✭
I want to get some advice, I live in FL I have been looking for a water heating solution and have decided to go solar. A local contractor "highly recommended by a friend" Is offering to install this unit;

http://www.theleveredge.com/solar_water_heater.htm

He states that I need a 120 gallon unit for my family of 5. He says that 80 gallons would be borderline for a family that size. Is that a fair assessment? I am hoping to eliminate most my heating cost, of course I will have to change some habits etc.

Now the only issue I have is that I have a hip roof and the panels can be on the right or left side of the house, which means that I will only be getting half a day worth of sun or so. The 80 gallon tank comes with one solar panel and the 120 gallon comes with two panels for water heating and a small panel to provide electricity to the pump. His bid price on this project is 5k, is that too much or a fair charge? Is this an ok system or is there a better system? I think he is willing to install and charge me for install if I buy the parts. Just want to get the most bang for my buck.


Thanks for any feedback and help in advanced.

Comments

  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Solar watert heater

    I can't comment on the price of this system as I am not familiar with it, but since it doesn't involve a second tank, it sounds kind of steep.

    I would question however, as to how this system uses the back up heating element in the water tank. It seems to me that when ever you draw off a small bit of water, you are introducing cold, and the t-stat would call for the element to heat. I must be missing something. In the systems that I am familiar with, the solar acts as a pre-heat tank for either a demand water heater, or a second tank. Perhaps someone with direct experience with a similar system should comment.


    Since you live in a non freezing, warm weather climate this should be a snap.

    Tony
  • BB.BB. Super Moderators, Administrators Posts: 31,090 admin
    Re: Solar watert heater

    The "average" is around 20 gallons per day of hot water per person (5x20=100 gallon minimum)... Too small of storage tank will cause you to use the backup heating source.

    If your intent is to use the sun as much as possible--I would round up rather than down. Also, if you have kids--they will use lots of hot water.

    Also, did they tell you how many sq.ft. of panels you will be getting... Generally there should be around 1-2 gallons of storage per sq.ft. foot of panel (if I understand the sizing, the more sun you get, the more hot water storage capacity it can support).

    Also, a larger tank can be more energy conserving (hold the hot water longer).

    One thing I did not see is a "tempering valve"... A solar hot water system can easily get over 120F (180F or more?). And there, for safety, needs to be a valve that will mix cold water with your hot solar water to help reduce the likely hood of scalding.

    Lastly, if you have natural gas (or possibly propane), you might be better off with that vs a electric backup heating element. Depending on the price of power, and how much alternate heat you need, there may be a surprise (during cloudy weather).

    Lastly, you might look at one of their installations and see if:
    1. Everything that is exposed to sun is UV proof, including foam insulation (and/or covered)
    2. Can you get parts to repair a pump, change out a tank, etc. (if you want).
    3. If there is enough backup heat for when there is no sun/failed pump, etc. (many backup electric water heaters just one element in the top of the tank and only heat ~30% of the water).
    4. Are the collectors repairable? Some have glass covers, others plastic. The plastic cover may only last 10 years (but is supposed to be cheap and easy to replace for one brand).
    5. What about a power outage (backup generator for hot water pump or solar panel). If you have electric hot water already--that is no different than today for you.
    6. Where are the panel(s) being installed (roof, wall?)--Need near new roof or walls in good repair--don't want to pull up panels in 10 years to re-roof.
    Not saying that you have to have 1-5, just questions I would ask and see if the answers are satisfactory to you.

    I would look around at other vendors (at least on line)--just to understand better what you are getting (I don't know anything about your vendor or product--pricing sounds OK from others I have read about).

    I would suggest reading through the links in this post...

    This specific link is very interesting. Guy installed solar hot water (with backup) in his barn. Very detailed, with parts lists, and photos how he installed everything... Including his mistakes (causing problems with trapping air and wrong pump orientation causing shortened pump life).

    Yes, you can run some pumps directly from a solar panel, and the guy I just typed about made (and is now selling) his own low power thermal controller that runs off of battery/solar (don't know anything else about guy or his products other than what I read on his website).

    I keep thinking I want to get a system too--but I don't have a good place for the tank, and with natural gas, I would need another heater/tankless water heater--makes it a bit more expensive.

    You can look at solarroofs.com as they make "kits" for self installs. One of the other posters here (Solar Guppy) has put a couple in and they work fine. They also have list pricing on their website.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Solar GuppySolar Guppy Solar Expert Posts: 1,963 ✭✭✭
    Re: Solar watert heater

    The link looks very similar to a solarroof product, probably the exact same technology, different manufacture ... which is a stretch as anyone can build the same system with parts from many online sellers

    120 gallon would be correct, you didn't list the sf of the collectors, I's say you need 60-80sf ( two 40ft would be ideal, one placed on each roof face )

    an open loop system has some draw-backs, you have to be careful with freezing temperatures, usually the controller will circulate from the storage tank when the collectors fall below 38F ( the goldline controller does this )

    5K, seems fair, that's the 50/50 rule, take any project in parts cost, double for someone else to do it, and make sure they pull the permits if your paying to have it installed .. here in Florida you will get into the wind code and that can be a pain, also make sure they have insurance and workman's comp ... they fall off your roof YOU PAY if they are uninsured

    I believe you can get a tax-credit for 30% of the 5K so thats a bit of a help
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Solar watert heater

    SG,

    Just out of curiosity, how does a single tank system handle incoming cold water triggering the t-stat to call for heat?

    Tony

    PS Is goldline still in business? I heard they went under, and when I tried to find some parts for a controller I was dead ended?
  • NomoreNomore Registered Users Posts: 18 ✭✭
    Re: Solar watert heater

    Thanks for all the great advise and comments. I will ask this questions tomorrow. I am curious like icarus on how this set up works with the cold water, the only thing I see is that the water that goes to the panels is sucked out the bottom of the tank, the cold water comes on the bottom of tank and the hot water returned from the hot panels is returned on top of tank. The electric heating element is on the top of the tank. I am not sure if it makes sense as I would think that the cold water would mix with the hot one as soon as it comes in on the bottom.

    I do not have access to propane or natural gas in my area. :(



    Is there a better tank set up or a better brand? I just want to get it right the first time around.


    I was looking a the drain back systems but not sure I understand how they operate.

    Thanks
  • Solar GuppySolar Guppy Solar Expert Posts: 1,963 ✭✭✭
    Re: Solar watert heater
    icarus wrote: »
    SG,

    Just out of curiosity, how does a single tank system handle incoming cold water triggering the t-stat to call for heat?

    Tony

    PS Is goldline still in business? I heard they went under, and when I tried to find some parts for a controller I was dead ended?


    On the ones I did, a regular HW tank was used and the hot water is returned to the top and sucked out the bottom ( for the collectors ). The tank thermostat is set lower than the solar HW differential controller was set at ( maximum temperature ), this gave a good 20-30 degrees of wiggle room and the top is used I believe for the temperature on the tank electric. Further, one disconnects the lower element. This helps in that the upper element will only heat maybe 1/3rd of the water to satisfy the thermostat. Also, 6 months of the year, we just shut off the breaker, no need for backup .. so that helped I guess

    In Central Florida, we got 9-10 months of the year 100% solar for two with stock 50 gallon tank and 40sf of collectors

    On Goldline, I see the controllers for sale everywhere so not sure what the answer is. Great controller and low cost for the features
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Solar watert heater

    SG,

    Thanks for the info,

    Looking at the tank configuration I was guessing at to how it worked. I think the advantage of having a preheat tank is obvious, so that you never use the electric element. I suppose in a warmer climate the headaches of a second tank or a demand might not make sense. In a colder climate, where you may only raise the temperature to say 70f in the winter from say 55 it is not an insignificant issue. Raising the water that much is ~15% of the total.

    Tony

    PS Do you have a source of goldline thermistors?
  • NomoreNomore Registered Users Posts: 18 ✭✭
    Re: Solar watert heater

    After looking at the estimate, I believe this are the panels he quoted me;

    http://kingsolar.com/catalog/mfg/aet/ae-32.html

    Are two of these fine or would you recommend a different one?
  • BB.BB. Super Moderators, Administrators Posts: 31,090 admin
    Re: Solar watert heater

    Looks good... I don't know anything else about the vendor or the product--but it seems to be well made with a thought to future repairs (if needed).

    At 2x30 sq.ft. and five people, I would see if I can could leave room to mount a third panel (and how much that would cost) to your system if you decide you need more hot water.

    Generally, solar thermal panels are about 1/10 the cost (per watt collected) vs solar electric--so I would not try and get away with the minimum installation if you guys use a lot of hot water (with kids).

    How your panels are mounted (tilted at latitude +15 degrees) would give you more winter collection and help prevent overheating during the summer.

    Solar Guppy, or your installer, may/should be able to understand what the drawbacks would be if you "over panel" the installation (don't want to overheat or boil the water during the summer).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Solar GuppySolar Guppy Solar Expert Posts: 1,963 ✭✭✭
    Re: Solar watert heater

    The issue with over-panel is the water can super-heat in the panels when the controller stops circulating in the summer when the HW tank hits its maximum temperature. If the water starts to be released to keep the panels from blowing up, they some tank water will be let out, not a huge deal but you need to make sure you have a pressure release at the top of the loop

    A couple of ways to help with this is a large HW tank, mount the panels at a angle optimum for winter so summer is off-angle and less efficient.

    I have bought stuff from KingSolar ... they seem to carry just about everything, I got most of my pool solar stuff thru them ( controller , auto valve ect )

    I'd suggest 2 panels ( 60sf ) and a 120 gallon tank and things should be good. The panels your looking at are much better quaility ( and about 4X the weight ) of the solarroof panels

    So if the bid was for 2 panels, a new 120 gallon tank, all the install I think that's a reasonable price if done with permits and insurance ect
  • BB.BB. Super Moderators, Administrators Posts: 31,090 admin
    Re: Solar watert heater
    ...make sure you have a pressure release at the top of the loop

    Would this be a T&P valve (Temperature and Pressure)? Basically the same valve as in a water heater?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Solar watert heater

    You can buy T&P, or just T's or just P's. I see no reason not to use a T&P as they are readily available and cheap. The T&P will release with excess pressure just as a P will. P's only may be hard to find at your local Home Depot.

    Tony
  • Solar GuppySolar Guppy Solar Expert Posts: 1,963 ✭✭✭
    Re: Solar watert heater

    I thought I would throw out some alternatives to solar thermal, since you live in FL like me we have many options, and all cost less than solar thermal


    Two technologies are desuperheat aka heat recovery from an heat pump and a dedicated heat pump for just the HW tank


    desuperheat example:

    http://www.acdirect.com/xcart/product.php?productid=2174

    This gets installed between the compressor and condenser of an existing heat-pump, which most of us in Florida Have. It is a double savings as it extracts heat just after the compressor and thru the exchanger, make hot water. for 9-10 months out of the year can do 100% of a large house-hold load.

    Even paying for an AC guy to do the install, your only looking at 1200-1500 for the same btu's solar thermal at 5K would do. It also improves the efficiency of the heat pump by lowering the pressure the compressor sees, you can easilyy get 2-3 more SEER points adding this to ANY heat pump.

    Dedicated heat pump:

    https://airgenerate.3dcartstores.com/

    Is a do-it-yourself Heat Pump that mounts onto an existing HW tank. Heat Pumps generate 3X the btus as compared to resistive heating. I'm not sure the above unit can handle a large household load, but there are many manufactures of this. the Benefit is they don't require any refrigerant work, just basic plumbing skills

    A side benefit for this is the discharge is basically AC cooled air, if your HW tank is in the garage, it would help keep the temperatures down, a big plus for a typical Florida home both in heat load for the resistance and comfort

    I just finished putting in a new Heat-Pump ( DIY ) and am now looking to tackle the HW, which is just a stock 50 gallon electric ... My roof is full of 12KW of PV, so I have no room for thermal and looking at the cost/return, either of these solutions far exceed anything solar thermal can do for my location in central Florida

    Solar thermal is not maintenance free and my experience, while positive overall, has me looking at the above alternatives, for you being in Florida would warrant looking into alternatives
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Solar watert heater

    Right on SG,

    If you live in an Air conditioned climate, and you have to pay for the kwhs to REMOVE the heat, and then pay the kwhs to put it back in the water is crazy. The idea of using the AC unit is very smart.

    Tony

    PS -39f at home last night,,, no worries about AC though!
    PPS I just checked the official Environment Canada site for yesterdays highs and lows. I was wrong, it was only -38.9F last night, down from a high of -8.9f yesterday afternoon!
  • NomoreNomore Registered Users Posts: 18 ✭✭
    Re: Solar watert heater
    I thought I would throw out some alternatives to solar thermal, since you live in FL like me we have many options, and all cost less than solar thermal


    Two technologies are desuperheat aka heat recovery from an heat pump and a dedicated heat pump for just the HW tank


    desuperheat example:

    http://www.acdirect.com/xcart/product.php?productid=2174

    This gets installed between the compressor and condenser of an existing heat-pump, which most of us in Florida Have. It is a double savings as it extracts heat just after the compressor and thru the exchanger, make hot water. for 9-10 months out of the year can do 100% of a large house-hold load.

    Even paying for an AC guy to do the install, your only looking at 1200-1500 for the same btu's solar thermal at 5K would do. It also improves the efficiency of the heat pump by lowering the pressure the compressor sees, you can easilyy get 2-3 more SEER points adding this to ANY heat pump.

    Dedicated heat pump:

    https://airgenerate.3dcartstores.com/

    Is a do-it-yourself Heat Pump that mounts onto an existing HW tank. Heat Pumps generate 3X the btus as compared to resistive heating. I'm not sure the above unit can handle a large household load, but there are many manufactures of this. the Benefit is they don't require any refrigerant work, just basic plumbing skills

    A side benefit for this is the discharge is basically AC cooled air, if your HW tank is in the garage, it would help keep the temperatures down, a big plus for a typical Florida home both in heat load for the resistance and comfort

    I just finished putting in a new Heat-Pump ( DIY ) and am now looking to tackle the HW, which is just a stock 50 gallon electric ... My roof is full of 12KW of PV, so I have no room for thermal and looking at the cost/return, either of these solutions far exceed anything solar thermal can do for my location in central Florida

    Solar thermal is not maintenance free and my experience, while positive overall, has me looking at the above alternatives, for you being in Florida would warrant looking into alternatives


    Thanks for showing other possibilities, I like the idea of the unit working off the central air unit!
  • Solar GuppySolar Guppy Solar Expert Posts: 1,963 ✭✭✭
    Re: Solar watert heater

    Doesn't hurt that either system qualifies for a 300 dollar tax credit

    http://www.energystar.gov/index.cfm?c=products.pr_tax_credits

    If one did both the heat pump and heat recovery , your still looking at half the cost of solar and getting the same if not more BTU'S in return. Keep in mind, solar only works at best half the day, these products work all the time ...

    The more I look into this I coming to the conclusion solar thermal makes little sense for our climate

    I also read GE is coming out with a new line of Heat Pump Water heaters at the end of this year, target is 400 more than standard electric, with 60% reduction in energy usage

    http://www.genewscenter.com/content/Detail.asp?ReleaseID=3348&NewsAreaID=2
  • NomoreNomore Registered Users Posts: 18 ✭✭
    Re: Solar watert heater
    Doesn't hurt that either system qualifies for a 300 dollar tax credit

    http://www.energystar.gov/index.cfm?c=products.pr_tax_credits

    If one did both the heat pump and heat recovery , your still looking at half the cost of solar and getting the same if not more BTU'S in return. Keep in mind, solar only works at best half the day, these products work all the time ...

    The more I look into this I coming to the conclusion solar thermal makes little sense for our climate

    I also read GE is coming out with a new line of Heat Pump Water heaters at the end of this year, target is 400 more than standard electric, with 60% reduction in energy usage

    http://www.genewscenter.com/content/Detail.asp?ReleaseID=3348&NewsAreaID=2


    Ok I am a little confused now, how do I know if my AC has the heat pump or is this something I need to purchase separately?

    What is the difference from solar thermal and the unit I was considering originally?
  • Solar GuppySolar Guppy Solar Expert Posts: 1,963 ✭✭✭
    Re: Solar watert heater
    Nomore wrote: »
    Ok I am a little confused now, how do I know if my AC has the heat pump or is this something I need to purchase separately?

    What is the difference from solar thermal and the unit I was considering originally?

    Look up your model number online and see if its a heat pump or just an AC unit.

    The difference between the two is minor, a heat pump is an AC unit that has a reverser valve that allows it to run "backwards", so instead of cooling, it heats. A heat pump is 2-4X more efficient at making heat that straight resistive heating

    Now the add-on heat recovery unit will work fine for a regaulr AC unit, but only for the cooling season ( 6-8 months a years in Florida ), A heat pump will allow the recovery unit to work year round

    Solar thermal IS what you were looking at, basically collectors on the roof with fluid for heat transfer from the collectors to the water tank.
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