AC Coupled System
Very interesting thread. I had a 3.5 kW grid-tied system installed two years ago. I love it but I might have held off had I known about some of these advances. Like Dave, I would be very happy to use my PV system as a back-up power supply during daytime hours. In the event that the SHTF, my main concern is running my well pump and a few hours each day would be more than sufficient.
The Ni-Fe batteries are promising and that SMA inverter that can function off grid I looks great. However, my system was installed with Enphase micro-inverters. At the time it seemed smart as one panel/inverter can fail while the others continue to work. But…and this is where I hope some of you smarter than I am might chime in…it is my understanding that it is difficult or even impossible to convert a micro-inverter system into an off-grid or hybrid system.
I hope I'm wrong about that. Does anyone know of a practical way to do that?
Here is a link to AC coupling. This might do what you wanted.