Inverters should be equipped with automatic anti-islanding, which causes the inverter to shut off when it no longer detects power from the grid supplier (there

Inverters should be equipped with automatic anti-islanding, which causes the inverter to shut off when it no longer detects power from the grid supplier (there are a few different ways to detect this). A lot of inverters built for grid-tie applications can't function without a mains connection anyway because of the way they track the frequency (unity power factor output). There can be a danger to first responders on the DC side of the inverter, which may still have a high DC potential from the panels (string voltage can be 100vdc and up). Fortunately, code in a lot of areas (in general areas that have adopted a 2014 or newer NEC) requires a "DC Rapid Shutdown" feature on new solar installations. In these systems there is a small module on each panel that detects the loss of a signal from the inverter and disconnects the panel from the string, eliminating the shock hazard from the panel cabling. This way the panels just get hot instead of producing power. That's only going to be on newer installations but at least NEC requires a big "DC Rapid Shutdown" sticker on the inverter if so. These systems can also be useful to avoid "cold start" overvoltage problems.