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    solar troubleshooting

    Battery backup not engaging during outage

    Common symptoms: battery not backing up; no power during outage; battery won't discharge; backup didn't kick in; critical loads dark

    Stop and call a pro if:

    • home batteries store lethal energy even when the system reads 'off' — never open the battery enclosure or touch its terminals
    • do not disconnect battery DC conductors (arc-flash); leave service to a certified installer
    • a swollen, hissing, hot, or leaking battery is an emergency — evacuate and call the fire department

    Step-by-step diagnostic flow

    1. Step 1

      Is the battery swollen, hot, leaking, hissing, smoking, or showing a hardware/thermal fault on its indicator?

      Lithium home batteries can fail dangerously. Any of these signs means evacuate and call for help.

    2. Step 2

      In the battery app, what is the state of charge, and is a backup reserve set?

      Many systems hold a backup reserve; if the battery is already drained below reserve, it has nothing to deliver during an outage.

    3. Step 3

      Is backup/island mode actually enabled in the app, and are the loads you expect on the backed-up (critical-loads) subpanel?

      Only circuits wired to the protected/critical-loads subpanel get backup power. Some systems also have a backup toggle that can be left off.

    4. Step 4

      At the critical-loads subpanel, is the main feed breaker on and none of the backed-up branch breakers tripped?

      Only operate clearly labeled breakers. Do not open the gateway, transfer switch, or battery enclosure.

    Possible outcomes

    Stop — battery emergency, evacuate

    high confidence

    A swollen, hot, leaking, hissing, or smoking battery can lead to thermal runaway and fire.

    Safe next steps
    • Leave the area and keep others away
    • Do not touch or try to disconnect the battery
    • Call the fire department, then your installer
    Battery thermal/physical hazard

    Battery was already drained below its reserve

    high confidence

    If the battery is at or below its backup reserve when the outage hits, there's little or no stored energy to deliver.

    Safe next steps
    • Let the battery recharge (from solar or, once the grid returns, from the grid)
    • Review your reserve setting so more charge is held for outages
    • Note that solar can only recharge the battery in daylight during a long outage
    What to document for a pro
    • Your backup reserve setting
    • State of charge when the outage began

    Backup is disabled or loads aren't on the backup subpanel

    high confidence

    Backup only powers circuits on the protected subpanel, and some systems have a backup toggle that may be off.

    Safe next steps
    • Enable backup/island mode in the app if it's off
    • Confirm with your install paperwork which circuits are on the backup subpanel
    • Move any must-have load onto the backup subpanel via your installer — not DIY
    What to document for a pro
    • Which loads you expected to stay on
    • Your critical-loads subpanel circuit list

    Tripped subpanel breaker — backup restored

    high confidence

    A tripped branch breaker on the critical-loads subpanel can leave backed-up circuits dark; resetting it restored power.

    Safe next steps
    • Confirm the backed-up circuits are live
    • If the breaker trips again, stop resetting it and call an electrician — repeated trips signal an overload or fault
    What to document for a pro
    • Which breaker tripped and whether it repeats

    No app/system data — have your installer check it

    low confidence

    Without battery/gateway communication you can't confirm state of charge or backup status, and a comms or controller fault may be why backup didn't engage.

    Safe next steps
    • Check that the gateway has power and network
    • Contact your installer to pull system logs remotely
    What to document for a pro
    • Battery and gateway make/model
    • Whether the gateway shows any lights
    • When backup last worked

    Likely transfer/island contactor or controller fault — call your installer

    medium confidence

    With charge available, backup enabled, loads on the subpanel, and no tripped breaker, the system isn't islanding — typically a gateway/transfer-switch contactor or controller fault that requires service.

    Safe next steps
    • Do not open the gateway, transfer switch, or battery enclosure
    • Photograph any fault indicators in the app and on the hardware
    • Schedule your installer and reference the warranty
    What to document for a pro
    • Battery and gateway make/model
    • State of charge and backup reserve setting
    • Any fault codes shown during the outage
    • Date/time of the outage when backup failed
    Battery/gateway service is not DIY
    Diagnostic guidance only. If unsure, stop and call a licensed professional — gas, electrical, and refrigerant work is hazardous to untrained users.

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