I'm curious about how two anti-islanding inverters work in the event of a power outage. If I have two inverters that are designed to shut off during outages, can they somehow keep each other going? I mean, if one inverter produces power that the other sees as grid power, could this create a situation where they both stay active and potentially backfeed? How do these inverters know they aren't actually connected to the grid?
3 Answers
Typically, two anti-islanding inverters won't keep each other running without the grid. For them to operate in island mode, they need grid-forming capabilities, and most are grid-interactive. So, in the absence of grid voltage and frequency, they should turn off as intended.
They will indeed shut off due to how the anti-islanding function works. These inverters constantly try to detect any phase shifts in the grid. If they only detect each other, the phase shifts will show that there’s no solid grid, prompting them to shut down. Having multiple inverters can actually speed up the shutdown process since they all react to each other’s attempts to shift the phase.
Yes, they might stay on for a brief moment if they think they’re still synced. But it's crucial that parallel inverters are specifically listed to work together safely. Generally, if you're looking to expand your system later, it's best to ac couple them with a grid-forming hybrid inverter.
Exactly! It's all about how they detect those phase shifts. Even if they could momentarily see each other as a grid, they'll eventually trip off.