Best way to use two inverters for one load?

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: 2,514 ✭✭✭✭✭
    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 
    900W  3 × 300W No name brand Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal as a backup system. 
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergencies and welding.
  • HRTannerHRTanner Registered Users Posts: 8 ✭✭
    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: 3,134 ✭✭✭✭✭
    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: 28,325 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: 181 ✭✭✭
    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: 28,325 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: 181 ✭✭✭
    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: 3,134 ✭✭✭✭✭
    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
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