A few months ago I had two guys that was out replacing a security lamp that quit burning. They were not pro on home owners selling power back to the grid. What I'm talking about would not be cost-effective but it would just make sure that I could charge an EV even if the grid was down and maybe just quit using the grid for everything depending how much money I put into the system.
The problem is most PV inverters will not run without a 60 Hz pilot signal from grid tie. This is thought to be a safety feature to keep from driving the grid during an outage putting linemen at risk. There are inverters for pure off grid. There are inverters which have simultaneous battery, PV, and grid connections.
One of the more unusual requirements of a grid tie installation is placement and documentation of an accessible disconnect.
Tesla PV installations start with an “Energy Gateway” through which everything is routed. All grid power enters. All PV power fed to the grid exits through it whether utility utilizes 1 or 2 meters. Some utilities accept this as the utility disconnect.
In the event of an outage the Energy Gateway disconnects from the grid so Tesla Powerwalls (battery with built in inverter and charge controller) can continue to power your home. With the added benefit of fooling your grid tie PV inverter into continuing to operate.
One nontrivial trick the Gateway must accomplish is to resync your 60 Hz to the utility 60 Hz when power resumes.
Do not need PV solar to have Powerwalls. They are sold to onerous T.O.U. customers who have excessive daytime rates tgat they can charge at night to have cheaper power during the day. Doubles as backup power.
Am told one Powerwall plus Gateway is $10,000 installed. Additional Powerwalls are $7,000 each. A Powerwall has 13 kWh or storage.
These are important concerns to me too as I am in the early stages of planning a new house. Already own the property. Have given consideration to being totally off-grid but to do so no-compromise looks to be $100-150k. Most of that is battery storage.