If Powerwall cannot charge at its expected rate, it will signal your solar inverter to reduce or turn off to protect your home from the excessive power produced. Powerwall shifts the frequency of power delivered to the inverter so it is outside of the acceptable tolerance range for the inverter, and the inverter must shut down. You may see lights flicker and/or sensitive electronics may be affected (briefly) when this happens. This typically occurs when Powerwall is approaching 100% charge. Once Powerwall has the ability to accept power again, your solar inverter will be signaled to produce and will re-start after the qualification period required by your local requirements (typically 5 minutes).
You will typically see this pattern during outages:
- If the solar is producing as your battery system nears 100%, your battery system will signal the solar to shut down
- Your backed-up circuits will then be using battery power only
- Once your battery charge level reaches a certain threshold (~75%-85%), your battery system will signal the solar to turn back on
- As your battery system nears 100% again, this process will repeat from step 1
This is necessary to prevent the solar system from producing excess energy when there is nowhere for it to go. Normally, this excess energy would go back to the grid. However, when the grid is down, your system is disconnected from the grid, so the solar must shut down to prevent excess energy from being produced.