Best way to use two inverters for one load?

HRTannerHRTanner Registered Users Posts: 15 ✭✭
I have been noticing several people have a "Daytime" system and "Night" system, which really intrigues me. As several people have noticed I have an inverter/charger that is way overboard for my daily load, but I don't want to get rid of it because it handles everything I would want to run at one time, as long as the sun is up. When the sun goes down the inverter "uses" more power than the house, just to stay on.

So I'm thinking I may just put together a "Night" system to power just my LED lights and Satalite TV/Internet, using a much smaller and more efficient inverter. This would be powered by a 2/2 configuration of 12v-200ah batteries, and charged by a 2/2 config of 285w PV panels.

So the question is, how to hook both inverters to my house power panel, whithout causing any feedback or anything else I don't know would happen?

Any expert advice is greatly appreciated.
Aimes Power 12KW Inverter/Charger, 15-285W Panels in 5/3 config, Aimes Power 60A MPPT Controller. 12-200Ah Renogy Batteries in 4/3 config for 48Vs
Off Grid, Whole house system in the Mohave Desert.

Comments

  • mcgivormcgivor Solar Expert Posts: 2,811 ✭✭✭✭✭
    Thiss can be accomplished with an auto transfer switch with the main inverter on normal power and the smaller on standby. This could be timed, which is how I do it, by programming an invert block period, not possible with many inverters, but with some creative thinking almost anything is possible, or the inverter could be manually turned off. This is the transfer switch I use for reference 

     https://www.aliexpress.com/item/ATS-2P-63A-230V-Micro-Circuit-Breaker-Dual-Power-Automatic-transfer-switch-Auto-transfer-switch/32868401442.html?
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • HRTannerHRTanner Registered Users Posts: 15 ✭✭
    Awesome, that's exactly what I need, as I plan to have the larger inverter as the main so I can just turn on the smaller inverter and turn the main off. Simple.
    Thank you very much.
    Aimes Power 12KW Inverter/Charger, 15-285W Panels in 5/3 config, Aimes Power 60A MPPT Controller. 12-200Ah Renogy Batteries in 4/3 config for 48Vs
    Off Grid, Whole house system in the Mohave Desert.
  • EstragonEstragon Registered Users Posts: 3,581 ✭✭✭✭✭
    I have multiple circuits that can be run from either the big inverters, or a small 300w Morningstar, so I used a panel like this:

    https://www.homedepot.ca/en/home/p.60-amp-generator-panel-with-18-spaces-36-circuits-maximum.1000722301.html

    Another regular panel has the circuits running stuff like pumps that can only run on the big inverters.
    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
  • BB.BB. Super Moderators, Administrators Posts: 28,998 admin
    You can also get manual genset transfer panels... You can wire the main panel to your main AC inverter... And the small inverter to the "generator" input... And switch circuits between Main/Small inverter as needed.

    Personally, I highly suggest that if you do have a large/small AC inverter (eventually, you should change out the big inverter to something a bit nicer).

    And that you only have one battery bank/Solar array/solar charge controller(s).  Keep the one bank happy is difficult enough--Having two banks and solar arrays+chargers--Now you have 2-4x the number of issues.

    Finding "smaller" 48 VDC inverters can be a bit difficult... But I believe you will be much happier.

    Cotek (and Samlex) inverters are pretty decent inverters (Quality/$$)... Here are some 48 VDC input inverters from our host NAWS:

    https://www.solar-electric.com/residential/inverters/off-grid-inverters.html?nav_inv_input_voltage=439

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • t00lst00ls Solar Expert Posts: 200 ✭✭✭
    HRTanner said:
    . As several people have noticed I have an inverter/charger that is way overboard for my daily load,
    When the sun goes down the inverter "uses" more power than the house, just to stay on.
    what...how is the inverter using more power than what loads are on...very inefficient or something is wrong with it

  • BB.BB. Super Moderators, Administrators Posts: 28,998 admin
    In general, a "small" (few hundred Watt) AC inverter can use 6 Watts just turned on a running (Tare Load).

    Larger inverters (in the 1,000's of watts) can use 20-40 Watt just turned. Seen some of the large, less expensive, AC inverters use even more.

    40 Watts * 24 hours per day = 960 WH per day

    A  very conservation minded home/cabin can use as little as 3,300 WH per day (fridge, lights, washing machine, well pump, TV, laptop).

    So--For smaller systems, yes, Tare Losses can be a significant load for off grid solar power systems. 40 Watt Tare Load is about the average load for a Energy Star rated full size refrigerator (1,000-1,500 WH per day in moderate climate).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • t00lst00ls Solar Expert Posts: 200 ✭✭✭
    never mind...I see it now
    Input Specifications
    • Nominal Input Voltage: 48.0Vdc
    • Low Battery Alarm: 42.0Vdc-44.0Vdc
    • Low battery Trip: 40.0Vdc-42.0Vdc
    • High Voltage Alarm: 64.0Vdc
    • Low battery Voltage Restart: 62.0Vdc
    • Idle Consumption: 200 Watts
    • Power Saver Mode Idle Consumption: 40 Watts
    • Automatic transfer switch - 63A @ 220/230/240V
    • Bypass - 63A @ 220/230/240V

      idle consumption is 200 watts.....wow...I would get rid of that thing

  • EstragonEstragon Registered Users Posts: 3,581 ✭✭✭✭✭
    An inverter may have  85-90% peak efficiency, but be near zero with a very light load relative to capacity.  My Outbacks use ~35w just being on, so 45w to run (eg) 10w load.  Run that 24hr, and it's 1000 watt-hrs for a 240wh load.  Mine are master/slave, so another ~200wh to keep the slave on standby, and becomes a fridge magnitude load which needs to be considered in planning.

    I turn the big inverters off when not needed overnight etc.
    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
  • TecnodaveTecnodave Registered Users Posts: 346 ✭✭✭
    edited February 10 #10
    I'm doing much the same but both inverters can run on either bank, Big inverter is MagnaSine MS-4024AE 120/240 4 kW , the smaller one is either a Cotek SK-1500 or a Exeltech 1100 watt unit. Cotek is for general duty and Exeltech is much quieter EMI wise and is used for communications. I use Square-D QO line generator transfer panels to switch in units used , 2 of them. One switches big/small the other switches between small inverters. I don't have breakers in those I use Square D QO Line switches meant for air conditioner cut off switches......Part QO 200..... note 2 pole 00 amp.  (they are not breakers so no amp trip rating)  These switches are rated 60 amps and are very rugged.

    Bit it of added info. Generator transfer panel is Square D QO 4/8 panel with solid copper busses. Most all small panels have tin plated aluminum busses. This panel will only take 2 double space 240 volt breakers and those are occupied by the QO line switches. My breakers are in separate QO line panels. 

    david
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Cotek SK-1500,Exeltech 1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or 10S LiFePO4,
  • jonrjonr Solar Expert Posts: 1,266 ✭✭✭✭
    edited February 10 #11
    Don't judge new inverters based on inverter size - check the actual minimum consumption while working (not stand-by idle).

    I am available for custom hardware/firmware development

  • westbranchwestbranch Solar Expert Posts: 5,136 ✭✭✭✭
    Dave you lost me somewhere...
    Are you running 2 of your Inverters constantly or when/where/how do you shut off the unused Inverters ie DC feed.
    tks
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • TecnodaveTecnodave Registered Users Posts: 346 ✭✭✭
    WB,
    No I normally run the MagnaSine day times and the Cotek when there is little load. The Cotek is more efficient at small loads than the MagnaSine, and I don't need 120/240 most times. The inverters are turned off when not used. Switching from bank to bank is done with MidNite 4 gang switches found in MidNite garage sale. These were 4 switches 150 volt 156 amp wired in series for an early birdcage project that was scrapped. I machined copper plate to gang them in parallel , walla a 150 volt 624 amp switch for $10.00 plus labor.  The little inverter is very quiet EMI wise and is used during radio programs that are faint here. No I'm not a ham. Just a broadcast junkie that does not want to hear the same music again . Shortwave radio.

    David
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Cotek SK-1500,Exeltech 1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or 10S LiFePO4,
  • TecnodaveTecnodave Registered Users Posts: 346 ✭✭✭
    WB,

    Littlr edit for clarity,
    The inverters are turned off at the inverter control panel itself....I leave the DC on to not shock the caps at startup. Easier on the gear.

    david

    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Cotek SK-1500,Exeltech 1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or 10S LiFePO4,
  • TecnodaveTecnodave Registered Users Posts: 346 ✭✭✭
    Estragon,

    I am sure that with only a 10 watt load your outback is using way more than idle plus load. The 85-90 percent effenicy is at 60-80 percent of full load .  Most 4kw inverters are about 30-40% efficiency at 10 watts so maybe 70-100 watts from battery to power that 10 watt load.

    david
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Cotek SK-1500,Exeltech 1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or 10S LiFePO4,
  • SaiproSaipro Solar Expert Posts: 73 ✭✭
    My 4kVA MustPower/PowerStar uses about 100W idle consumption. The higher the load, the less it burns on its own. Not a good inverter for night time loads. I had a smaller nameless Chinese brand for night time (about 30W) then switched to a hacked APC inline UPS. Victron MultiPlus 5kVA for daytime loads has an idle 25W consumption (had to retire it due to a fault which forced the fans at full revs constantly thus raising idle consumption to 50W. Returned to the MustPower). The Victron Phoenix for critical and night time loads has an self-consumption of roughly 10W in use thus perfect. Both are wired to the same bank. I use knife switch to switch between them. That way both can never feed the same circuits at the same time.
    Semi off-grid

    255W Canadian Solar × 12, Midnite Classic 150 with WizBang Jr, 200AH 48V US 185 XC2 bank, Victron MultiPlus 48V 5kVA inverter (daytime) Victron Phoenix 48V 375VA inverter (night time)

    150W JYSP × 2, Midnite Brat, 100AH 24V bank (powers DC LED security lights)

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