need help for an on/off grid Hsolarsystem

Comments

  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    So, i think I'm reading you bought an air conditioner, and want to run it off a battery powered inverter ?
    Is it this model ?
    https://www.amazon.com/Japanese-Daikin-Efficient-Inverter-Conditioner/dp/B00UCCOS9K

    If you have grid power, simply run it from the grid.
    If you don't have grid power, then you will need an extensive PV & battery system to run this.
    Often, inverter mini-splits start off at high power and throttle back to much less power when things have started to cool off.
    Can you tell us about the size of the room you intend to cool ?  Insulated?

    Rough calculations:
     2600W @ 30% duty cycle would consume 18720 watt hours, requiring a 37,440wh battery,    48V 780ah

     2600W @ 50% duty cycle would consume 31200 watt hours, requiring a 62,400wh battery,  48V, 1300ah

    I hope I did something wrong, because this looks just huge, but air conditioning is very power intensive









    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 ,

  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    edited February 2017 #3
    robocop said:

    Awaiting for help


    Some how your info got listed inn the "tagged" area for search links.

    If you want to work backwards, you have a 2600 watt load for 2 hours a day, that's about 6 Kwhs of load with the inverter inefficiency. 6 Kwhs load would draw down a 18 Kwh battery (at a 20 hour discharge rate) to about 50% when adjusted for the high rate of usage. If you assume you are only running it on sunny days in the summer time, but off batteries for night time sleeping. You would want about a 4000 watt array with about half facing south east and half facing south west. 

    You can always use 2 - 24 watt panels in series to have in essence a 48 volt battery.

    An 18 Kwh battery is roughly 18,000 /48 volts= 375 Amp hour batter bank at 48 volts or 750 amp hour at 24 volts.

    Lots of assumptions made here since you provided so little information.
    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.
  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    2x12v batteries only gives you 24v in series, not the 48v needed to run a 48v inverter.

    Assuming you run at 2500w for 3 hours:

    2500*3/48=156 amp hours@48v

    For long life, you want to avoid taking below 50%, and high load over short time means lower apparent capacity. Charging with solar we generally plan for 2 days of no sun - start the generator to charge on the third day. Taken together you might size a bank at around 700ah (20hr rate).

    For panels, you would want to use whatever is economical in your area. Typically large panels (250+watt) are the least cost/watt. Depending on location etc. you'll want about 20 of those (~4000w/58v charging =69a). You might want to go with more panels if you can time running the AC for when the sun is out. With more panel you could charge and cool at the same time.
    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
  • mvas
    mvas Registered Users Posts: 395 ✭✭✭
    mike95490 said:
    So, i think I'm reading you bought an air conditioner, and want to run it off a battery powered inverter ?
    Is it this model ?
    https://www.amazon.com/Japanese-Daikin-Efficient-Inverter-Conditioner/dp/B00UCCOS9K

    If you have grid power, simply run it from the grid.
    If you don't have grid power, then you will need an extensive PV & battery system to run this.
    Often, inverter mini-splits start off at high power and throttle back to much less power when things have started to cool off.
    Can you tell us about the size of the room you intend to cool ?  Insulated?

    Rough calculations:
     2600W @ 30% duty cycle would consume 18720 watt hours, requiring a 37,440wh battery,    48V 780ah

     2600W @ 50% duty cycle would consume 31200 watt hours, requiring a 62,400wh battery,  48V, 1300ah

    I hope I did something wrong, because this looks just huge, but air conditioning is very power intensive


    I think your math is as follows ...
    2,600 watts x 24 hours/day x 30% Duty Cycle = 18,720 watt-hours
    2,600 watts x 24 hours/day x 50% Duty Cycle = 31,200 watt-hours

    But the OP stated "only 2 - 3 hours per day".

    What if ...
    a) 2,600 watts x 3 hours/day x 30% Duty Cycle / 80% Eff = 2,925 watt-hours / 70% C3 / 50% DOD / 48 Volts = 174 AH Battery
    b) 2,600 watts x 3 hours/day x 50% Duty Cycle / 80% Eff = 4,875 watt-hours / 70% C3 / 50% DOD / 48 Volts = 290 AH Battery

    The above batteries will run the A/C at either 30% or 50% Duty Cycle for 3 hours with batteries discharged to 50% DOD.
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    If only running 3 hours a day, you will not be getting 30% duty cycle except for the last 10 minutes.
      maybe the OP will come back and clarify things,  but running 3 hours solid, will still suck power
    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 ,

  • mvas
    mvas Registered Users Posts: 395 ✭✭✭
    edited February 2017 #7
    Added 3 hours continuous run-time option ...

    a) 2,600 watts x 3 hours/day x  30% Duty Cycle / 80% Eff = 2,925 watt-hours / 70% C3 / 50% DOD / 48 Volts = 174 AH Battery
    b) 2,600 watts x 3 hours/day x  50% Duty Cycle / 80% Eff = 4,875 watt-hours / 70% C3 / 50% DOD / 48 Volts = 290 AH Battery
    c) 2,600 watts x 3 hours/day x 100% Duty Cycle / 80% Eff = 9,750 watt-hours / 70% C3 / 50% DOD / 48 Volts = 580 AH Battery