Put a transfer switch on the incoming line to a small inverter generator like a honda. The Solar inverter sees the Honda as the Grid then and will sync with it and run.
Most inverters have an offline mode, you set it up by putting critical circuits (refer and lighting, furnace blower, etc) on its own sub panel and putting in a switch over breaker setup. Power goes out, the critical circuits can be flipped over to run independantly.
Not a problem with the panels, its a problem with the guys that set it up thinking grid intertye, not TSHTF. Those solar panels were chugging away, the inverters were not wired to run due to short sighted installations.