Solar Battery Not Charging — 7 Common Causes and Fixes

A battery that stops charging means lost self-consumption, no backup power, and wasted solar energy. Before calling a technician, work through these seven common causes — most can be resolved in minutes.

1. Battery Type Not Set Correctly

The most common cause. If your Deye inverter is set to "No Battery" or the wrong battery type, it will not charge. Go to Settings > Battery Type in the inverter menu or SolarMan app and select "Lithium" for LiFePO4 batteries.

2. CAN Communication Cable Disconnected

The CAN cable carries BMS data between the battery and inverter. If disconnected or damaged, the inverter sees no battery. Check both ends of the CAN cable are firmly seated. Look for error code W03 on the inverter display.

3. Battery BMS Protection Active

The Battery Management System may have triggered protection due to over-temperature, over-voltage, or cell imbalance. Check the battery LED indicators. Most BMS protections reset automatically once conditions normalise. If not, power cycle the battery by disconnecting for 30 seconds.

4. Insufficient Solar Production

The battery only charges when solar production exceeds home consumption. On cloudy days or with heavily shaded panels, there may be no surplus power. Check the SolarMan app — if solar production is lower than consumption, the battery will not charge from solar alone.

5. Time-of-Use Settings Blocking Charge

If you have configured time-of-use scheduling, the inverter may be programmed not to charge during certain hours. Check Settings > Work Mode > Time of Use in the SolarMan app and verify your charge windows are correct.

6. DC Battery Breaker Tripped

A tripped breaker between the battery and inverter physically disconnects the battery. Check the DC breaker near the battery and reset if tripped. If it trips repeatedly, there may be a wiring fault — call an electrician.

7. Battery End of Life

If your battery is old (6+ years for gel, 15+ years for LiFePO4), it may have reached end of life and can no longer accept charge. Check the battery's State of Health (SOH) in the SolarMan app. Below 60% SOH indicates replacement is needed.

Quick Diagnostic Checklist

1. Check inverter display for error codes (especially W03, W05)
2. Verify battery type is correctly set in inverter
3. Check CAN cable connections at both ends
4. Check battery LED indicators for BMS protection status
5. Verify DC battery breaker is on
6. Check solar production vs consumption in SolarMan app
7. Review time-of-use schedule settings