Load Managment for Small Off-Grid System

DanS
DanS Registered Users Posts: 5 ✭
in Solar Beginners Corner #1
I am new to solar electric systems and would appreciate some good advice about load management for a small off-grid system.

I am designing an off-grid system based on a 12 Vdc 168 Ah AGM battery bank and two 140W Kyocera KD-140SX-UFBS solar modules (Voc 22.1 V, Isc 8.68 A & Vpm 17.7 V). I plan to use the Morningstar TS-MPPT-60 charge controller to recharge the battery bank. The TS-MPPT-60 is overkill at this point, but allows future expansion and control via a web brower.

The only load for this initial step is an DC-powered Engle refrigerator which draws 2.7 A @ 12 Vdc when the compressor is running.

I am considering adding the Sunsaver SS-MPPT-15L charge controller solely for its LVD feature to prevent the load from discharging the battery bank to a low SOC. The SS-MPPT-15L would have no input from the solar modules. The only input would be from the battery bank.

Can the SS-MPPT-15L be reliably used in this manner with no input connection from a solar module (i.e. utilizing only the SS-MPPT-15L Battery and Load terminals, with no connection to the Solar terminals)?

Is another approach better to provide protection to the battery bank from a low SOC?

Thank you.
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Comments

  • SolaRevolution
    SolaRevolution Solar Expert Posts: 410 ✭✭
    #2
    Re: Load Managment for Small Off-Grid System
    DanS wrote: »
    Is another approach better to provide protection to the battery bank from a low SOC?


    You may want to consider the Morningstar Relay driver:
    http://www.solar-electric.com/moredr.html


    The Relay Driver is designed to work with the TriStar charge controllers. Custom programming requires using "MS View" software and the proper connection cable but there may be presets for one of the four relays which could work for you.

    The Relay Driver would provide the "master" control and you would also need "slave" relays to control the loads. The 4 control channels can give you a multi-step control ability. It is cheaper than the Sunsaver SS-MPPT-15L too.


    From the manual:

    The Relay Driver is pre-configured at the factory with a default
    configuration as outlined below. If a different configuration is
    needed, a custom configuration will need to be programmed
    into the Relay Driver.

    Channel 1
    Threshold Function:
    Channel OFF when Vbattery < 11.5V
    Channel ON when Vbattery > 12.6V
    1 minute delay before turning on/off

    Channel 2
    Threshold Function:
    Channel OFF when Vbattery < 11.1V
    Channel ON when Vbattery > 12.2V
    1 minute delay before turning on/off

    Channel 3
    Threshold Function:
    Channel OFF when Vbattery < 14.0V
    Channel ON when Vbattery > 15.0V

    Channel 4
    TriStar Alarm/Fault Monitor:
    Channel OFF when no alarms/faults exist
    Channel ON when any alarms/faults exist
    Excludes RTS open alarm
    No communication timeout alarm

    -Alex
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  • DanS
    DanS Registered Users Posts: 5 ✭
    #3
    Re: Load Managment for Small Off-Grid System
    SolaRevolution wrote: »
    You may want to consider the Morningstar Relay driver:
    http://www.solar-electric.com/moredr.html


    The Relay Driver is designed to work with the TriStar charge controllers. Custom programming requires using "MS View" software and the proper connection cable but there may be presets for one of the four relays which could work for you.

    The Relay Driver would provide the "master" control and you would also need "slave" relays to control the loads. The 4 control channels can give you a multi-step control ability. It is cheaper than the Sunsaver SS-MPPT-15L too.


    From the manual:

    The Relay Driver is pre-configured at the factory with a default
    configuration as outlined below. If a different configuration is
    needed, a custom configuration will need to be programmed
    into the Relay Driver.

    Channel 1
    Threshold Function:
    Channel OFF when Vbattery < 11.5V
    Channel ON when Vbattery > 12.6V
    1 minute delay before turning on/off

    Channel 2
    Threshold Function:
    Channel OFF when Vbattery < 11.1V
    Channel ON when Vbattery > 12.2V
    1 minute delay before turning on/off

    Channel 3
    Threshold Function:
    Channel OFF when Vbattery < 14.0V
    Channel ON when Vbattery > 15.0V

    Channel 4
    TriStar Alarm/Fault Monitor:
    Channel OFF when no alarms/faults exist
    Channel ON when any alarms/faults exist
    Excludes RTS open alarm
    No communication timeout alarm

    -Alex


    Thanks, Alex. I had not noticed the Morningstar Relay Driver while reviewing their products. I appreciate you bringing this to my attention.

    Dan
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #4
    Re: Load Managment for Small Off-Grid System

    Good luck (NOT sarcastic) getting the MS View software to work. Apparently some people can get it to work, others, including myself cannot. I gave up after several tries and cables.
    From the display on the laptop, it looked like it would be awesome. Alas, for me it was not to be :(
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  • DanS
    DanS Registered Users Posts: 5 ✭
    #5
    Re: Load Managment for Small Off-Grid System
    waynefromnscanada wrote: »
    Good luck (NOT sarcastic) getting the MS View software to work. Apparently some people can get it to work, others, including myself cannot. I gave up after several tries and cables.
    From the display on the laptop, it looked like it would be awesome. Alas, for me it was not to be :(

    Thanks Wayne. I appreciate the heads-up.

    Dan
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  • CDN_VT
    CDN_VT Solar Expert Posts: 492 ✭✭✭
    #6
    Re: Load Managment for Small Off-Grid System

    I found the "MS View software" only seam to work with XP and No updates done from Microsnot . Just need to configure the Reg-edit of the computer system.
    for me It ran on XP 2003 ,SP2 or SP3 installed from a file. Some of the updates from MS stop functions.

    VT
    YMMV
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  • DanS
    DanS Registered Users Posts: 5 ✭
    #7
    Re: Load Managment for Small Off-Grid System
    CDN_VT wrote: »
    I found the "MS View software" only to work with XP and No updates done from Microsont . Just need to configure the Regedit of the computer system.
    for me It ran on XP 2003 ,SP2 or SP3 installed remotely form a file. Some of the updates from MS stopp functions.

    VT
    YMMV

    Thanks! I'll dig an old XP system out of the closet and reinstall the original OS. Glad now that I kept it.
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  • SolaRevolution
    SolaRevolution Solar Expert Posts: 410 ✭✭
    #8
    Re: Load Managment for Small Off-Grid System
    CDN_VT wrote: »
    I found the "MS View software" only seam to work with XP and No updates done from Microsnot . Just need to configure the Reg-edit of the computer system.
    for me It ran on XP 2003 ,SP2 or SP3 installed from a file. Some of the updates from MS stop functions.

    VT
    YMMV

    That's good to know. I use XP so it has not been a problem.

    -Alex
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #9
    Re: Load Managment for Small Off-Grid System
    CDN_VT wrote: »
    I found the "MS View software" only seam to work with XP and No updates done from Microsnot . Just need to configure the Reg-edit of the computer system.
    for me It ran on XP 2003 ,SP2 or SP3 installed from a file. Some of the updates from MS stop functions.

    I run MS-View on Windows 7 without any problems, it just installed and ran. Use it to configure MPPT 60.
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  • DanS
    DanS Registered Users Posts: 5 ✭
    #10
    Re: Load Managment for Small Off-Grid System
    stephendv wrote: »
    I run MS-View on Windows 7 without any problems, it just installed and ran. Use it to configure MPPT 60.

    Thanks Stephen - I'll give MS-View a try before pulling out the old XP PC.
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