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Tesla•Powerwall 3

Analysis by Marcus & Team

Tesla Powerwall 3 Discharging During Solar Charging

Troubleshoot Tesla Powerwall 3 discharging during solar charging. Diagnose and fix battery drain issues. Ensure optimal energy storage system performance.

Frequently Asked Questions

•What are the typical solar panel string voltage and current readings I should expect for my Powerwall 3 system?

Refer to your solar panel manufacturer's specifications for Voc and Isc. Multiply the Voc by the number of panels in series for string voltage. Compare measured values to these specifications under full sun.

•How do I perform a capacity test on my Tesla Powerwall 3?

Tesla handles Powerwall 3 capacity testing remotely. Monitor battery degradation via the app. Contact Tesla support for any significant capacity decline.

•Where can I find the Tesla Powerwall 3 service manual and troubleshooting guides?

Tesla provides limited access to service manuals directly to homeowners. Contact Tesla support for specific troubleshooting assistance and to access relevant documentation through them.

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Marcus leads the technical research department at Storage Faults. Together with a team of systems analysts, he specializes in translating complex solar storage error codes into actionable diagnostic steps for the US market.

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Critical Safety Precautions:

The Powerwall 3 operates with high DC voltages (up to 600V+). Improper handling can result in electric shock or arc flash. Always disconnect the DC input from the solar panels and the AC input from the grid before performing any maintenance. Adhere to NEC rapid shutdown requirements. Only qualified electricians should perform invasive measurements or repairs. Wear appropriate personal protective equipment (PPE), including insulated gloves and safety glasses.

Recommended Action:

1

Using a calibrated multimeter, verify the solar panel string voltage and current at the Powerwall 3's DC input terminals under full sunlight conditions. Compare readings to the manufacturer's specifications. Note open-circuit voltage (Voc) and short-circuit current (Isc).
2

Use a clamp meter to measure AC current at the main service panel to determine household energy consumption during the suspected discharge period.
3

Access the Powerwall 3's monitoring interface (via the Tesla app or web portal) to review historical energy data, including solar production, battery SOC, and grid import/export.
4

Examine the Powerwall 3's configuration settings, ensuring that TOU settings are correctly programmed and backup reserve levels are appropriate. Review any grid support settings to ensure they are not causing unintended battery discharge.
5

Using an IR thermometer, check the temperature of the Powerwall 3 enclosure and battery components for signs of overheating, which could indicate a battery management issue.
6

Inspect the wiring connections at the Powerwall 3 and solar panel array for loose or corroded connections. Refer to NEC 690 for solar PV system wiring requirements.
7

If the issue persists, contact Tesla support for advanced diagnostics and potential firmware updates or hardware replacement.

Possible Causes:

Inadequate solar panel output due to shading, soiling, or panel degradation.
Incorrect Powerwall 3 configuration settings, such as incorrect time-of-use (TOU) settings or backup reserve thresholds.
High household energy consumption exceeding solar production, causing the Powerwall to supplement power from the battery.
BMS malfunction leading to inaccurate SOC readings or premature discharge termination.
Grid support settings are incorrectly configured, causing the Powerwall to export power even with internal loads.
Firmware issues in the Powerwall's inverter or BMS.

Observed Symptoms:

Powerwall 3 is discharging (decreasing SOC) during daylight hours when solar panel production should be actively charging the battery. This results in reduced energy independence and potentially increased grid reliance during peak solar production.

How It Works:

The Powerwall 3 integrates a hybrid inverter which manages power flow between solar panels, the battery, the grid, and the home's electrical loads. MPPT algorithms maximize solar energy capture. DC power from the solar panels is converted to AC for household use or grid export. Excess DC power charges the lithium-ion battery. The Battery Management System (BMS) regulates charging/discharging, monitoring voltage, current, temperature, and SOC to protect the battery and optimize its lifespan. Anti-islanding protection ensures disconnection from the grid during outages. Grid synchronization maintains proper voltage and frequency (60Hz). AC coupling allows for retrofitting to existing solar systems. Rapid shutdown (RSD) per NEC requirements enables safe disconnection during emergencies.

Maintenance Tips:

Regularly monitor the Powerwall 3's performance via the Tesla app or web portal
Keep solar panels clean and free from shading
Perform periodic capacity tests (as recommended by Tesla) to assess battery health (SOH)
Ensure the Powerwall 3 firmware is up-to-date
Periodically check solar string voltages to identify degrading panels
Implement a scheduled BMS calibration as per manufacturer guidelines