Do Grid Tie Solar System Shut Down When The Power Goes Off?

An important limitation of grid-tie solar systems is that they shut off when the grid goes down, even if the sun is still shining. This automatic disconnection, called “anti-islanding”, is an important safety feature to protect utility workers who may be repairing lines during an outage. But it also means grid-tie solar provides no backup power during grid failures[1][3][6].

Why Grid-Tie Solar Systems Shut Down During Outages

Grid-tie solar systems utilize inverters to convert the DC output of solar panels into AC power that can be fed into the grid. These inverters are designed to immediately stop exporting power when they detect the grid has lost power or fallen out of acceptable voltage/frequency range[1][5].

There are two key reasons for this automatic disconnection:

  1. Safety – If solar systems continued exporting power, it could electrocute utility workers trying to repair lines and restore grid power. So anti-islanding is an important failsafe[1][3][5].
  2. Grid Stability – Without proper grid regulation, solar inverters could damage appliances or cause further instability if voltage/frequency fluctuates during an outage[5].

So while inconvenient for solar homeowners during outages, there are very good reasons for grid-tie solar to shut off when grid power is lost.

Options for Backup Power

For homeowners that want backup power from their solar panels during grid failures, there are a couple options:

  • Battery Storage – Adding a solar battery bank allows excess solar power to be stored and used during grid outages. Though this adds significant cost[6][7].
  • Off Grid SolarOff grid solar systems are not connected to the utility grid at all, instead storing power in batteries and running a home independently. But they require larger, more expensive battery banks[7][8].
  • Specialty Inverters – Some advanced inverters like SMA Sunny Boy can provide limited backup power during grid failures. Though output is lower and rewiring is required[7].

In short, with proper battery storage solar systems can provide backup power during outages. But grid-tie solar on its own will shut down for safety reasons anytime grid power is lost. Consumers should understand this key limitation before installing grid-tie solar.

Citations: [1] [2] [3] [4] [5] [6] [7] [8]