But how do they do it technically? Some countries require anti-islanding devices for grid connected solar, these are around $1000. That alone is much more expensive than the $300 plug in panels.
But how do they do it technically? Some countries require anti-islanding devices for grid connected solar, these are around $1000. That alone is much more expensive than the $300 plug in panels.
The inverter can sniff the grid power at frequent intervals to determine its voltage and phase.
It outputs at the same phase and frequency as the grid, and with a slightly higher voltage (think of a ball rolling down a slope from a higher voltage to lower voltage).
If the grid is down then it stops the inverter for a minimum safety period (some minutes iirc)