Happens if solar power fails when out of town?

softdown
softdown Solar Expert Posts: 3,844 ✭✭✭✭
in Off Grid Solar & Battery Systems #1
Had my first power failure in years. Overnight voltage dropped to ~ 41 volts due to cloudy weather and eight freezers and fridges.

No problem when here. Fired up genset and back in business.

What if the power fails due to low voltage when I am out of town?  Will it kick back on when the sun starts shining? Outback inverter and charge controller.

FWIW: 45 degree panel tilt at 37 degree latitude is great during the winter time. Sheds snow and ice fast too.

But performs poorly during the summer time. Exacerbated by eight freezers and fridges. 

Had problems last year at this time. Then fall hit and all was good. Need to eek out another month from these batteries. 

The batteries are still pretty strong. But eight freezers and fridges plus a dozen security cameras (most with spotlights) places unusual demands. 
First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
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  • softdown
    softdown Solar Expert Posts: 3,844 ✭✭✭✭
    #2
    I also freeze water and that seems to really drain the batteries. As does charging weak truck batteries.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,870 ✭✭✭✭✭✭
    #3
    Well you have to test it!  Set LBCO to a higher value while home with solar off. When power goes out you turn on solar and observe.

    All of these things depend on how the installer configured the system !
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • softdown
    softdown Solar Expert Posts: 3,844 ✭✭✭✭
    #4
    I used default settings
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
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  • Wheelman55
    Wheelman55 Registered Users Posts: 241 ✭✭✭
    #5
    Don’t know if this helps. I’ve got Schneider gear, lithium batteries with a closed system. 

    Dave A. helped me with my system back in the day. One of the tests that he asked me to do was to draw the batteries down to zero to cause a system shut down and to see if the system restarted when the sun rose in the morning. I did this twice and both times the system came back on. 

    Hope your’s does the same and thanks again Mr. A!
    Off-Grid in Terlingua, TX
    5,000 watt array - 14 CS 370 watt modules. HZLA horizontal tracker. Schneider: XW6048NA+, Mini PDP, MPPT 80-600, SCP. 390ah LiFeP04 battery bank - 3 Discover AES 42-48-6650 48 volt 130ah LiFePO4 batteries
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  • JRHill
    JRHill Registered Users Posts: 336 ✭✭✭
    #6
    I don't understand why you would not set the inverter to shut down sooner to protect what is left of the batteries?

    But to your question, my system came back on as expected**. But if you pull the batteries down too low and you want to know what unexpected consequences you'll pay this would be a good way to find out.

    **Many years back with my original Trojan L16s nearing end of life I did some experimenting on a heavily clouded day. I don't recall what I had set the Low Voltage Cut Out but it was probably around 50.5 for 15 seconds and the VX3648 shut down as expected. What I hadn't expected was how fast the bank's voltage rebounded and it didn't take long for Low Voltage Cut IN to turn the inverter back on. Then it didn't take long and the sequence repeated. I sure the heck didn't like that and no part of the solar equipment or my appliances benefited from the power cycles. My realization was to make sure the Cut IN voltage and delay was high and long enough that if the sun didn't come out and I wasn't home or unaware that I didn't have the power on and off cycle repeating.
    Off Grid. Two systems: 1) 2925w panels, OB VFXR3648, FM80, FNDC, Victron BMV-712, Mate3s, 240 xformer, four SimpliPHI 3.8; 2) 780w, Morningstar 30a, Grundfos switch, controller and AC/DC pump, 8 T105. Honda EU7000is w/AGS. Champion 3100. HF 4550, Miller Bobcat.
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