Generac PWRcell › Problems
Generac PWRcell ATS won't switch to backup power during an outage
The Generac PWRcell automatic transfer switch (ATS) does not switch the home to backup power during an outage, or does not switch back to utility power afterwards. This page covers what the lights and codes mean, what to check first, and the causes behind it.
What the lights mean
| What you see | What it means |
|---|---|
| Inverter light blinking green | The inverter is in Island Mode because the utility service is interrupted. |
| Inverter light green | The utility is connected and its voltage and frequency are normal. |
| Inverter light red | The inverter is overloaded or has a serious fault. Someone likely has to step in before it runs again. |
Error codes that go with this problem
| Code | What it means |
|---|---|
| State 0x7721 on the inverter | The inverter is not set up for an ATS, but it has detected one. |
What to check first
- Look at the inverter's device page for a fault code such as State 0x7721, and note it for your installer.
- Check that the protected loads breaker is on. The ATS needs it on to work.
- If the inverter shows State 0x7721, you can call Generac phone support. The wait can be long, but support was able to find the problem for an owner who had this code.
- Call your installer if the ATS still does not switch. The remaining checks are of the inverter settings and the ATS wiring, contactor and controller, and some need the power removed first.
Safety. The ATS contactor is checked only with the power removed.
The causes and the fixes
Partners see the causes behind this problem, most common first, the checks that tell them apart, and the fix for each, with part numbers and recent prices when a part is involved.