If you have 1-to-1 net metering and flat rates for electricity and no TOU, Powerwall provides no benefit there. Just “store” your extra power generated as a net meter credit.
If you have reliable power and don’t mind that solar will not be operating when the grid is down, Powerwall provides no benefit. That last bit a lot of people learn later rather than sooner, is that the grid needs to be up for solar to operate so that there is a place to send excess generation.
Those things being said, there are other considerations for Powerwalls. Besides powering your bunker during the zombie apocalypse, there might be state, utility, or regional incentives. Our state has a solar generation credit that we get paid a few cents for every kw of solar produced whether we use that for our home or export it to the grid. This incentives is increased a few more cents per kw if battery storage is used in the home. So check that out in your area, it pays back some of the Powerwall investment.
Another incentive might be if there is a virtual power plant program that your utility is part of. These VPP programs pay homeowners with battery storage for the privilege of the utility to draw power from the battery during times of high load. The program here in New England will pay us over about five years the amount for the cost of the Powerwalls after federal tax rebates.