Off-grid Minisplits: 3-Zone Single Unit or 3 Separate Units

AnawaAnawa Solar Expert Posts: 211 ✭✭✭
Looking for some advice for a 3 Minisplit application:  9k + 9k + 18k. What is more efficient: 3 separate units or 3-Zone set-up. 

Thanks
Paul 
in Georgia

System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k

Comments

  • mike95490mike95490 Solar Expert Posts: 8,503 ✭✭✭✭✭
    I think I would prefer the 3 independent systems.   if one failed, you have others that can help.  May not be the most efficient, as larger units have higher eff ratings.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • stillchillinstillchillin Registered Users Posts: 44 ✭✭✭
    The multi zone system is the way to go IMO. By the way you can not get a multi zone system in straight cooling, only heat pumps that may help make up your mind if you only need cooling. If installed by a professional you should get years of service with no more than annual cleaning. Check out the Mitsubishi multi zone units. I have installed many of these with no problems. I may be wrong on the straight cooling multi zone units, Mitsubishi does not offer them maybe in another make. What I like about the multi zone units is there is only one power circuit for the one condensing unit, also only one condensing unit to look at. all IMO
    18- 235 W Kyocera panel, 12- 4-KS-25PS Rolls 1350 Ah, Magnum MS4448PAE, ME RC50, ME AGS, Outback FM 80, Generac 8KW LP generator, 6.5 Honda Portable generator
  • Dave AngeliniDave Angelini Solar Expert Posts: 4,877 ✭✭✭✭✭
    I am with Mike, adding that I do not think you can buy a multi with the same high SEER that a 9,000 or 12,000 can get. They always seem lower in multi. I think the units in this range should be over 25 SEER  and some are over 30. The higher, the longer you can run at night (or during a wildfire or bad solar day) without dipping into the bank offgrid.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • AnawaAnawa Solar Expert Posts: 211 ✭✭✭
    Thanks guys. 

    A major concern in this application is the owner is new to the off-grid life style and is a bit resistive to not having unlimited A/C. To deal with this and try to keep the PV system "practical", I'm suggesting an 18k in the main area (open kitchen, dining, living) for daytime operation and the 9k's in each of the bedrooms. The 9k would essentially be for nighttime, when needed. Obviously, the "when needed" is subjective and is directly related to both the ambient temperature and your pocket book. The overall floor area is slightly less than 1,500 sf.

    Dave, you're right about the seer ratings being lower on the multi's. Looks like separate units may be the way to go, especially when they will probably be running at night. Anybody got thoughts on minimum seer for my application? 
    Paul 
    in Georgia

    System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
    System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
    System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
    System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
  • jonrjonr Solar Expert Posts: 1,351 ✭✭✭✭
    I would consider using a Chiltrix heat pump, a large water tank and air handlers.  The idea being to only run it while the sun shines and minimize use of the batteries.  If not, then consider a Fujitsu 12RLS3.  Should be plenty for a well insulated 1,500 sf house with the bedroom doors open and overhead fans.

    I am available for custom hardware/firmware development

  • Dave AngeliniDave Angelini Solar Expert Posts: 4,877 ✭✭✭✭✭
    I think you should go back and read my thread on this from around 10 years ago when I first did this for Offgrid over in the energy section.
     Probably what I see in your design that is wrong (to me) is not having a big open floor plan and just cooling the whole house with a 1 ton and having extra units to supplement if needed. Looks like too much and way to hard to run from solar unless you are going to be running generators all the time.
    Think small and start early with a tracked array, then run late tracked!
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

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