Small electric hot water heater

wellbuilt
wellbuilt Solar Expert Posts: 763 ✭✭✭✭
in Off Grid Solar & Battery Systems #1
Hi all , my question for the board is , is it possible to just plug in a 20 gallon electric water heater .
 The heater has a 1500 watt element . 
 I was thinking this would be fast and easy for some temporary hot water for showers .
  I have a 3600 watt out back inverter  and 4200 watts of solar with a 415 ah battery bank  that is drawn down to 85 /90% full at night .
  I have a lot of power going to wast this time of year . 
  I just need a little more time to get my Permanent radiant heat floor hot water system working
   In October / November I turn off the water befor is freezes  . 
Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
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Comments

  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #2
    It shouldn't be a problem, I'd just run it on a timer from say 1-4 in the afternoon. Then there is no risk of it drawing down your system over night. Check the recovery on the water heater to see what they expect it to take to fully heat, I can't recall the parameters, likely they are not regulated. 
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • wellbuilt
    wellbuilt Solar Expert Posts: 763 ✭✭✭✭
    #3
    Thanks photowhit  I figured it would be ok , do you think I would be better off running it from solar panels directly with out inverter or 
     CC 
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #4
    No, If you have a large enough inverter, I'd just run it off AC it'll use a tad more electric, but I have struggled with trying to be comfortable with a DC design, but high voltage DC doesn't work well with the thermostat, so you would have to have a relay to run the DC electric that would shut it off from a thermostat run off AC.


    I run a 3600 volt 240 volt element on 120 volts. It runs at 1/4 the wattage or 900 watts. Takes quite a while in a 30 gallon tank.

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • wellbuilt
    wellbuilt Solar Expert Posts: 763 ✭✭✭✭
    #5
     Did you pick the heating element deliberately or did you just buy the water heater and make it work ? 
     Or did you want to stay at 900 watts ?
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
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  • NANOcontrol
    NANOcontrol Registered Users Posts: 276 ✭✭✭
    #6
    It depends on your array voltage and the water heater.  I have a 6 gallon ECOsmart with a 120V 1500W element. That is a good match for 60 so volts. You can't change this heating element. Another tank has a 120V 2000W element. screw in and these are common elements that could replace 240V ones. I use a circuit that keeps the panels above the power point voltage. That allows me to operate the heater in parallel with a charge controller without going thru the batteries. It will send as little as 5W to the heater to more than 500W the entire day. A 5500W 240V element is 10.5 ohms.  With your number of panels, a direct connect wouldn't be that bad using a timer. A fixed resistance load really drags down a panels voltage in less than prime sun. I'm low usage and I have all the hot water I need with only about 2700WH a day.  My system works similar to this.


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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #7
    wellbuilt said:
     Did you pick the heating element deliberately or did you just buy the water heater and make it work ? 
     Or did you want to stay at 900 watts ?
    It came with the mobile home. I installed the system intending to get a 240 volt inverter, but just used the 120 volt one from my cabin and used the extra energy produce in the afternoon to heat water. It has provided about 80% of my hot water use as an opportunity load.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #8
    Seems to me at least some 20 gal tanks run on 120v out of the box.  Depending on inlet water temp and set temp, I think 1500w would take ~2hrs to reheat 20 gals.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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  • wellbuilt
    wellbuilt Solar Expert Posts: 763 ✭✭✭✭
    #9
    Yes the water heater is 120 volt  , that is what I was thinking 2 hrs should fine . 
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
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  • wellbuilt
    wellbuilt Solar Expert Posts: 763 ✭✭✭✭
    #10
    Nice vid nano , I my try that in the Future
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
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