I’d be retrofitting that bad boy with a valve.
As for solar, you might as well drop a battery bank in and do wind too. In doing that you can put a shunt on the solar plant and divert the power during an outage.
They will never know. As soon as the power comes on the shunt opens back up and diverts the power back to the grid.
I’m watching my favorite solar gear company (GoalZero.com) and noting that they’re sold out of mid-range batteries (around 1kWh). Wondering if they’ll sell out of more soon...